U.S. patent application number 16/416344 was filed with the patent office on 2019-09-19 for passenger carrying unmanned aerial vehicle powered by a hybrid generator system.
The applicant listed for this patent is Top Flight Technologies, Inc.. Invention is credited to Eli M. Davis, Samir Nayfeh, Long N. Phan.
Application Number | 20190283874 16/416344 |
Document ID | / |
Family ID | 63245565 |
Filed Date | 2019-09-19 |
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United States Patent
Application |
20190283874 |
Kind Code |
A1 |
Phan; Long N. ; et
al. |
September 19, 2019 |
PASSENGER CARRYING UNMANNED AERIAL VEHICLE POWERED BY A HYBRID
GENERATOR SYSTEM
Abstract
An unmanned aerial vehicle includes at least one rotor motor
configured to drive at least one propeller to rotate; a passenger
compartment sized to contain a human or animal passenger; and a
hybrid generator system configured to provide power to the at least
one rotor motor and to generate lift sufficient to carry the human
or animal passenger. The hybrid generator system includes a
rechargeable battery configured to provide power to the at least
one rotor motor; an engine configured to generate mechanical power;
and a generator motor coupled to the engine and configured to
generate electrical power from the mechanical power generated by
the engine.
Inventors: |
Phan; Long N.; (Somerville,
MA) ; Nayfeh; Samir; (Shrewsbury, MA) ; Davis;
Eli M.; (Cambridge, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Top Flight Technologies, Inc. |
Malden |
MA |
US |
|
|
Family ID: |
63245565 |
Appl. No.: |
16/416344 |
Filed: |
May 20, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15593535 |
May 12, 2017 |
10308358 |
|
|
16416344 |
|
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|
62339284 |
May 20, 2016 |
|
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|
62335938 |
May 13, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B64D 27/24 20130101;
Y10T 464/10 20150115; B64C 2201/146 20130101; B64C 2201/066
20130101; B64C 39/026 20130101; B64C 2201/027 20130101; B64C 39/022
20130101; B64C 39/024 20130101; B64C 2201/042 20130101; B64C
2201/18 20130101; B64C 2201/141 20130101; B64D 2027/026
20130101 |
International
Class: |
B64C 39/02 20060101
B64C039/02; B64D 27/24 20060101 B64D027/24 |
Claims
1. An unmanned aerial vehicle comprising: at least one rotor motor
configured to drive at least one propeller to rotate; a passenger
compartment sized to contain a human or animal passenger; and a
hybrid generator system configured to provide electrical energy to
the at least one rotor motor and to generate lift sufficient to
carry the human or animal passenger, the hybrid generator system
comprising: a rechargeable battery configured to provide electrical
energy to the at least one rotor motor; an engine configured to
generate mechanical energy; and a generator motor coupled to the
engine and configured to generate electrical energy from the
mechanical power generated by the engine.
Description
CLAIM OF PRIORITY
[0001] This application is a continuation application of U.S.
patent application Ser. No. 15/593,535, filed on May 12, 2017,
which claims priority to U.S. Patent Application Ser. No.
62/339,284, filed on May 20, 2016, and to U.S. Patent Application
Ser. No. 62/335,938, filed on May 13, 2016, the contents of which
are incorporated here by reference in their entirety.
BACKGROUND
[0002] A multi-rotor unmanned aerial vehicle (UAV) may include
rotor motors, one or more propellers coupled to each rotor motor,
electronic speed controllers, a flight control system (auto pilot),
a remote control (RC) radio control, a frame, and a rechargeable
battery, such as a lithium polymer (LiPo) or similar type
rechargeable battery. Multi-rotor UAVs can perform vertical
take-off and landing (VTOL) and are capable of aerial controls with
similar maneuverability to single rotor aerial vehicles.
SUMMARY
[0003] In an aspect, an unmanned aerial vehicle includes at least
one rotor motor configured to drive at least one propeller to
rotate; a passenger compartment sized to contain a human or animal
passenger; and a hybrid generator system configured to provide
electrical energy to the at least one rotor motor and to generate
lift sufficient to carry the human or animal passenger. The hybrid
generator system includes a rechargeable battery configured to
provide electrical energy to the at least one rotor motor; an
engine configured to generate mechanical energy; and
[0004] a generator motor coupled to the engine and configured to
generate electrical energy from the mechanical power generated by
the engine.
[0005] Embodiments can include one or more of the following
features.
[0006] The electrical energy generated by the generator motor is
provided to at least one of the rotor motor and the rechargeable
battery.
[0007] The unmanned aerial vehicle includes a climate control
system configured to control one or more of a temperature, a
humidity, and an oxygen content within the passenger compartment.
The climate control system receives electrical energy from one or
more of the generator motor and the rechargeable battery.
[0008] The unmanned aerial vehicle includes a control system
configured to enable the passenger to cause the unmanned aerial
vehicle to land. The control system is configured to receive
information indicative of a destination from the passenger. The
control system is configured to receive operating instructions from
a remote control center.
[0009] The passenger sized compartment is positioned on a top side
of a frame of the unmanned aerial vehicle.
[0010] The passenger sized compartment is positioned on a bottom
side of a frame of the unmanned aerial vehicle.
[0011] The passenger sized compartment is sized to contain a single
human passenger.
[0012] The rechargeable battery is sized to provide at least a
minimum amount of electrical energy.
[0013] The unmanned aerial vehicle includes a weather sensor
configured to detect weather conditions.
[0014] The unmanned aerial vehicle includes a control system
configured to automatically modify a flight plan based on data
detected by the weather sensor.
[0015] The unmanned aerial vehicle includes a sensor configured to
detect a condition of one or more components of the unmanned aerial
vehicle. The unmanned aerial vehicle includes a control system
configured to automatically modify a flight plan based on data
detected by the sensor.
[0016] The unmanned aerial vehicle includes an energy absorbing
connector, in which the hybrid power generation system is coupled
to a frame of the unmanned aerial vehicle through the energy
absorbing connector.
[0017] The hybrid energy generation system is configured to
generate at least 150 kW of electrical power.
[0018] The hybrid energy generation system is configured to
generate up to 1 MW of electrical power.
[0019] The generator motor is rigidly coupled to the engine.
[0020] The generator motor is coupled to the engine by a metal
plate.
[0021] The engine includes one or more of a two-stroke
reciprocating piston engine, a four-stroke reciprocating piston
engine, a gas turbine, and a rotary engine.
[0022] The unmanned aerial vehicle includes a cooling system
configured to cool the hybrid energy generation system.
[0023] The generator motor comprises one or more of a permanent
magnet synchronous generator, an induction generator, and a
switched reluctance generator.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIGS. 1 and 2 are diagrams of passenger-carrying UAVs.
[0025] FIG. 3 is a diagram of a passenger compartment.
[0026] FIGS. 4A and 4B are diagrams of control interfaces.
[0027] FIG. 5 depicts a diagram of an example hybrid generator
system.
[0028] FIG. 6 depicts a side perspective view of a hybrid generator
system.
[0029] FIG. 7A depicts a side view of a hybrid generator.
[0030] FIG. 7B depicts an exploded side view of a hybrid
generator.
[0031] FIG. 8 is a perspective view of a hybrid generator
system.
[0032] FIG. 9 is a perspective view of a UAV integrated with a
hybrid generator system.
[0033] FIG. 10 depicts a graph comparing energy density of
different UAV power sources.
[0034] FIG. 11 depicts a graph of market potential for UAVs against
flight time for an example two plus hours of flight time hybrid
generator system of one or more embodiments when coupled to a UAV
is able to achieve and an example of the total market potential vs.
endurance for the hybrid generator system for UAVs.
[0035] FIG. 12 shows an example flight pattern of a UAV with a
hybrid generator system.
[0036] FIG. 13 depicts a diagram of a hybrid generator system with
detachable subsystems.
[0037] FIG. 14A depicts a diagram of a hybrid generator system with
detachable subsystems integrated as part of a UAV.
[0038] FIG. 14B depicts a diagram of a hybrid generator system with
detachable subsystems integrated as part of a ground robot.
[0039] FIG. 15 shows a ground robot with a detachable flying pack
in operation.
[0040] FIG. 16 shows a control system of a hybrid generator
system.
[0041] FIGS. 17-19 are diagrams of a UAV.
[0042] FIGS. 20 and 21 are diagrams of portions of a hybrid
generator system.
[0043] FIGS. 22A and 22B are diagrams of portions of a hybrid
generator system.
[0044] FIG. 23 is a diagram of a portion of an engine.
DETAILED DESCRIPTION
[0045] We describe here an unmanned aerial vehicle (UAV) powered by
a hybrid generator and that can be used, e.g., for short distance
point-to-point passenger transportation. These passenger-carrying
UAVs include a passenger compartment to contain one or more
passengers during transit. The hybrid generator of these
passenger-carrying UAVs is scaled (e.g., for output power, load
performance, etc.) to generate sufficient lift to carry the
passenger and his personal items, and can be designed with
sufficient redundancy to ensure the safety of the passenger.
[0046] Referring to FIG. 1, in some examples, a passenger-carrying
UAV 100 includes a passenger compartment 102 sized to carry a
single passenger. The passenger compartment 102 is positioned above
a frame 104 of the UAV. The passenger-carrying UAV 100 includes a
hybrid generator system that includes multiple rotors 106 each
coupled to a propeller 108, as described in greater detail below.
The propellers 108 generate sufficient lift to carry the
passenger-carrying UAV 100 and the contents of the passenger
compartment 102 (e.g., a person and the person's personal items,
such as a suitcase). Referring to FIG. 2, in some examples, a
passenger compartment 202 can be positioned below a frame 204 of a
passenger-carrying UAV 200.
[0047] In the examples of FIGS. 1 and 2, the UAVs 100, 200 include
passenger compartments 102, 202 that are sized to carry a single
passenger. In some examples, the passenger compartments 102, 202
can be sized to carry multiple passengers, such as two, three,
four, five, or another number of passengers. When the passenger
compartment 102, 202 is sized to carry multiple passengers, the
hybrid generator can be configured to generate a greater amount of
lift in order to carry the greater weight of multiple passengers.
For instance, the hybrid generator can include larger motors and
propellers, a larger number of rotors and propellers, can include
an engine configured to generate a larger amount of power, etc.
[0048] Referring to FIG. 3, the interior of the passenger
compartment 102 can include amenities for the comfort and/or safety
of a passenger. For instance, the passenger compartment 102 can
include a seat 300 with a seatbelt 302, a climate control system
304 to maintain the interior of the passenger compartment 102 at a
comfortable temperature, humidity, and/or oxygen content; an
entertainment system 306, such as an audio or video system; a
computing device, etc.; one or more lights 308; storage space 310
for the passenger's personal belongings; or other amenities. The
passenger compartment 102 can be equipped with a communications
system 312, such as a wireless Internet system, a radio system
through which the passenger can communicate with a remote control
center, or other types of communications capability.
[0049] In some examples, a control interface is housed in the
interior of the passenger compartment. The control interface can
enable the passenger to have varying degrees of control over the
operation of the UAV 100. Referring to FIG. 4A, in some examples, a
limited control interface 316 provides the passenger with only
limited ability to control the operation of the UAV. For instance,
the limited control interface 316 includes portions of the
communications system 312 (e.g., a speaker 318 and a microphone
320) and an emergency button 322, which the passenger can press in
the event of an emergency (e.g., a medical emergency, an equipment
failure, or another reason) to cause the UAV to land quickly. The
operation of a UAV equipped with a limited control interface 316
can be primarily controlled by a remote control center, which can
transmit coordinates or an address of a destination to the UAV,
initiate a flight, or perform other control tasks. Referring to
FIG. 4B, in some examples, a control interface 324 can provide the
passenger with additional control capabilities. For instance, the
control interface 324 includes the additional features of a screen
326 (e.g., a touch sensitive screen) into which the passenger can
enter coordinates or an address of a destination and a start button
328, which the passenger can press to initiate the flight.
[0050] The passenger carrying UAVs described here are powered by a
hybrid generator system that is sized to generate sufficient lift
to carry the passenger and his personal items. For instance, the
hybrid generator system can be sized to carry up to about 200
pounds, up to about 250 pounds, up to about 300 pounds, or another
weight. In some examples, a large safety tolerance can be designed
into the hybrid generator system. For instance, the hybrid
generator system can be sized to carry more weight than the amount
of weight permitted in the passenger compartment during operation
of the UAV.
[0051] The hybrid generator system powering the passenger carrying
UAVs described here can be designed with redundancy in order to
ensure the safety of the passengers. For instance, a multi-rotor
UAV can be designed to fly safely even when one or more of the
rotors or propellers are disabled. The UAV can be equipped with
large batteries in order to provide enough power to allow the UAV
to land safely in the event of an engine failure. The UAV can
utilizes sensors, such navigational sensors, atmospheric or weather
sensors, or other types of sensors, to detect wind conditions, to
monitor its own health, or to perform other monitoring, e.g., in
order to anticipate and/or avoid hazardous flying conditions. The
battery system and electrical controls can be designed to
automatically and seamlessly provide system power in case of loss
of primary engine power. When this happens, the passenger carrying
UAV can be diverted for a safe landing at the closest emergency
landing point. Within an area of operation, emergency landing
points can be defined and the battery pack sized such that in all
cases of operation there will always be sufficient energy for the
passenger carrying UAV to reach an emergency landing point under
battery power.
[0052] The sensor array can be used to monitor local weather
conditions and prohibit flight in the case of unsafe conditions
(high winds, excessive ambient temperatures, high rain or low
visibility), or to terminate an existing flight plan or modify a
flight plan in the case of changing weather conditions. The sensor
array can also be used to monitor the performance of the critical
flight components to ensure safe operation and monitor for required
maintenance. For example, temperature sensors on the propeller
motors can be used to monitor operating temperature versus load. If
the motor operating temperature falls outside a predefined range,
the motor will be flagged for inspection prior to the next flight.
In some examples, an existing flight plan can be modified or
terminated based on results of monitoring performance of the flight
components.
[0053] In a specific example, a UAV sized to carry a single
passenger and personal items weighing up to 100 kg weighs between
about 250 kg and about 350 kg and carries between about 50 kg and
about 150 kg of fuel. Such a UAV utilizes approximately 125 kW of
electric power to fly, and therefore utilizes an engine capable of
producing approximately 150 kW or mechanical power.
[0054] The engine can be a two-stroke reciprocating piston engine,
a four-stroke reciprocating piston engine, a gas turbine, a rotary
engine, or another type of engine.
[0055] Passenger carrying UAVs can be used to transport people for
short distance point-to-point transportation to or from areas of
low population or areas that are hard to access using conventional
transportation infrastructure. In an example, passenger carrying
UAVs can be used for inter-island transportation in island
archipelagos, e.g., between islands of Japan, Hawaii, the
Philippines, or other regions having closely spaced islands.
Passenger carrying UAVs can be used to provide air transportation
services to islands, towns, or regions that do not have enough
population to justify regular commercial air service or whose
geography makes a standard airport impractical. Passenger carrying
UAVs can be used for short distance urban travel, e.g., acting as a
taxi that is not subject to traffic patterns or delays. In some
instances, the UAVs can assist with personnel movements within a
particular facility or venue; for example, to efficiently move
individuals to various locations within an airport, a sporting
venue, an industrial or military complex, etc.
[0056] In some examples, the passenger compartment of a passenger
carrying UAV can be modified to be suited for animal
transportation, such as for transportation of livestock or wild
animals. For instance, if a cow falls ill while grazing far from
its ranch, the cow can be loaded onto a passenger carrying UAV
equipped for livestock transportation and returned to its ranch or
to a veterinary facility for treatment. Similarly, an injured
endangered animal encountered in the wild can be loaded onto a
passenger carrying UAV and transported to a zoo or veterinary
facility for treatment, and subsequently returned to its wild
environment.
[0057] The UAV 100 can be powered by a hybrid generator system that
provides an portable hybrid generator power source with energy
conversion efficiency. In UAV applications, the hybrid generator
system can be used to overcome the weight of the vehicle, the
hybrid generator drive, and fuel used to provide extended endurance
and payload capabilities in UAV applications.
[0058] The hybrid generator system can include two separate power
systems. A first power system included as part of the hybrid
generator system can be a small and efficient gasoline powered
engine coupled to a generator motor. The first power system can
serve as a primary source of power of the hybrid generator system.
A second power system, included as part of the hybrid generator
system, can be a high energy density rechargeable battery.
Together, the first power system and the second power system
combine to form a high energy continuous power source and with high
peak power availability for a UAV and for other components housed
on the UAV, such as components for navigation, data processing,
data storage, communications, or other capabilities. In some
examples, one of the first power system and the second power system
can serve as a back-up power source of the hybrid generator system
if the other power system experiences a failure.
[0059] FIG. 5 depicts a diagram of an example hybrid generator
system 500. The hybrid generator system 500 includes a fuel source
502, e.g., a vessel for storing gasoline, a mixture of gasoline and
oil mixture, or similar type fuel or mixture. The fuel source 502
provides fuel to an engine 504, of a first power system. The engine
504 can use the fuel provided by the fuel source 502 to generate
mechanical energy. In one example, the engine 504 can have
dimensions of about 12'' by 11'' by 6'' and a weight of about 3.5
lbs to allow for integration in a UAV. In one example, the engine
504 may be an HWC/Zenoah G29 RCE 3D Extreme available from Zenoah,
1-9 Minamidai Kawagoe, Saitama 350-2025, Japan. The hybrid
generator system 500 also includes a generator motor 506 coupled to
the engine 504. The generator motor 506 functions to generate AC
output power using mechanical power generated by the engine 504. In
some examples, a shaft of the engine 504 includes a fan that
dissipates heat away from the engine 504. In some examples, the
generator motor 506 is coupled to the engine 504 through a
polyurethane coupling.
[0060] In some examples, the hybrid generator system 500 can
provide 1.8 kW of power. The hybrid generator system 500 can
include an engine 504 that provides approximately 3 horsepower and
weighs approximately 1.5 kg, e.g., a Zenoah.RTM. G29RC Extreme
engine. The hybrid generator system 500 can include a generator
motor 506 that is a brushless motor, 380 Kv, 8 mm shaft, part
number 5035-380, available from Scorpion Precision Industry.RTM.. A
hybrid generator system 500 that provides 1.8 kW of power can
operate with an RPM output of about 6000 rpm.
[0061] In some examples, the hybrid generator system 500 can
provide 10 kW of power. The hybrid generator system 500 can include
an engine 504 that provides approximately between 15-16.5
horsepower and weighs approximately 7 pounds, e.g. a Desert
Aircraft.RTM. D-150. The hybrid generator system 500 can include a
generator motor 506 that is a Joby Motors.RTM. JM1 motor. A hybrid
generator system 500 that provides 10 kW of power can operate with
a high RPM output, such as about 6000 rpm, and can exhibit good
reliability and a long life span. A hybrid generator system 500
providing 10 kW of power can be suitable for unmanned UAVs, such as
UAVs for freight transport, surveillance, or data collection and/or
processing.
[0062] In some examples, the hybrid generator system 500 can
provide 100 kW of power. In some examples, the hybrid generator
system 500 can provide up to 1 MW of power, such as about 120 kW,
150 kW, 200 kW, 300 kW, 400 kW, 500 kW, 600 kW, 700 kW, 800 kW, 900
kW, or 1 MW of power. For instance, a hybrid generator system 500
can include a Continental Diesel CD-155 piston engine or a Lycoming
iE2 piston engine coupled to a 120 kW generator. The generator can
be one or more of a permanent magnet synchronous generator, an
induction generator, a switched reluctance generator, or other
types of rotary generators. A hybrid generator system 500 that
provides 120 kW of power can be suitable for a manned or passenger
carrying UAV.
[0063] The hybrid generator system 500 includes a bridge rectifier
508 and a rechargeable battery 510. The bridge rectifier 508 is
coupled between the generator motor 506 and the rechargeable
battery 510 and converts the AC output of the generator motor 506
to DC power to charge the rechargeable battery 510 or provide DC
power to load 518 by line 520 or power to DC-to-AC inverter 522 by
line 524 to provide AC power to load 526. The rechargeable battery
510 may provide DC power to load 528 by line 530 or to DC-to-AC
inverter 532 by line 534 to provide AC power to load 536. In one
example, an output of the bridge rectifier 508 and/or the
rechargeable battery 510 of hybrid generator system 500 is provided
by line 538 to one or more electronic speed control devices (ESC)
514 integrated in one or more rotor motors 516 as part of an UAV.
The ESC 514 can control the DC power provided by bridge rectifier
508 and/or rechargeable battery 510 to one or more rotor motors
provided by generator motor 506. In one example, the ESC 514 can be
a T-Motor.RTM. ESC 45A (2-6S) with SimonK. In one example, the
bridge rectifier 508 can be a model #MSD100-08, diode bridge 800V
100A SM3, available from Microsemi Power Products Group.RTM.. In
some examples, active rectification can be applied to improve
efficiency of the hybrid generator system.
[0064] In some examples, the ESC 514 can control an amount of power
provided to one or more rotor motors 516 in response to input
received from an operator. For example, if an operator provides
input to move a UAV to the right, then the ESC 514 can provide less
power to rotor motors 516 on the right of the UAV to cause the
rotor motors to spin propellers on the right side of the UAV slower
than propellers on the left side of the UAV. As power is provided
at varying levels to one or more rotor motors 516, a load, e.g. an
amount of power provided to the one or more rotor motors 516, can
change in response to input received from an operator.
[0065] In some examples, the rechargeable battery 510 may be a LiPo
battery, providing 3000 mAh, 22.2V 65C, Model PLU65-30006,
available from Pulse Ultra Lipo.RTM., China. In other designs, the
rechargeable battery 510 may be a lithium sulfur (LiSu)
rechargeable battery or similar type of rechargeable battery.
[0066] The hybrid generator system 500 includes an electronic
control unit (ECU) 512. The ECU 512, and other applicable systems
described in this paper, can be implemented as a computer system, a
plurality of computer systems, or parts of a computer system or a
plurality of computer systems. In general, a computer system will
include a processor, memory, non-volatile storage, and an
interface. A typical computer system will usually include at least
a processor, memory, and a device (e.g., a bus) coupling the memory
to the processor. The processor can be, for example, a
general-purpose central processing unit (CPU), such as a
microprocessor, or a special-purpose processor, such as a
microcontroller.
[0067] The memory can include, by way of example but not
limitation, random access memory (RAM), such as dynamic RAM (DRAM)
and static RAM (SRAM). The memory can be local, remote, or
distributed. The bus can also couple the processor to non-volatile
storage. The non-volatile storage is often a magnetic floppy or
hard disk, a magnetic-optical disk, an optical disk, a read-only
memory (ROM), such as a CD-ROM, EPROM, or EEPROM, a magnetic or
optical card, or another form of storage for large amounts of data.
Some of this data is often written, by a direct memory access
process, into memory during execution of software on the computer
system. The non-volatile storage can be local, remote, or
distributed. The non-volatile storage is optional because systems
can be created with all applicable data available in memory.
[0068] Software is typically stored in the non-volatile storage.
Indeed, for large programs, it may not even be possible to store
the entire program in the memory. Nevertheless, it should be
understood that for software to run, if necessary, it is moved to a
computer-readable location appropriate for processing, and for
illustrative purposes, that location is referred to as the memory
in this paper. Even when software is moved to the memory for
execution, the processor will typically make use of hardware
registers to store values associated with the software, and local
cache that, ideally, serves to speed up execution. As used herein,
a software program is assumed to be stored at an applicable known
or convenient location (from non-volatile storage to hardware
registers) when the software program is referred to as "implemented
in a computer-readable storage medium." A processor is considered
to be "configured to execute a program" when at least one value
associated with the program is stored in a register readable by the
processor.
[0069] In one example of operation, a computer system can be
controlled by operating system software, which is a software
program that includes a file management system, such as a disk
operating system. One example of operating system software with
associated file management system software is the family of
operating systems known as Windows.RTM. from Microsoft Corporation
of Redmond, Washington, and their associated file management
systems. Another example of operating system software with its
associated file management system software is the Linux operating
system and its associated file management system. The file
management system is typically stored in the non-volatile storage
and causes the processor to execute the various acts required by
the operating system to input and output data and to store data in
the memory, including storing files on the non-volatile
storage.
[0070] The bus can also couple the processor to the interface. The
interface can include one or more input and/or output (I/O)
devices. The I/O devices can include, by way of example but not
limitation, a keyboard, a mouse or other pointing device, disk
drives, printers, a scanner, and other I/O devices, including a
display device. The display device can include, by way of example
but not limitation, a cathode ray tube (CRT), liquid crystal
display (LCD), or some other applicable known or convenient display
device. The interface can include one or more of a modem or network
interface. It will be appreciated that a modem or network interface
can be considered to be part of the computer system. The interface
can include an analog modem, isdn modem, cable modem, token ring
interface, Ethernet interface, satellite transmission interface
(e.g. "direct PC"), or other interfaces for coupling a computer
system to other computer systems. Interfaces enable computer
systems and other devices to be coupled together in a network.
[0071] A computer system can be implemented as a module, as part of
a module, or through multiple modules. As used in this paper, a
module includes one or more processors or a portion thereof. A
portion of one or more processors can include some portion of
hardware less than all of the hardware comprising any given one or
more processors, such as a subset of registers, the portion of the
processor dedicated to one or more threads of a multi-threaded
processor, a time slice during which the processor is wholly or
partially dedicated to carrying out part of the module's
functionality, or the like. As such, a first module and a second
module can have one or more dedicated processors, or a first module
and a second module can share one or more processors with one
another or other module s. Depending upon implementation-specific
or other considerations, a module can be centralized or its
functionality distributed. A module can include hardware, firmware,
or software embodied in a computer-readable medium for execution by
the processor. The processor transforms data into new data using
implemented data structures and methods, such as is described with
reference to the FIGS. in this paper.
[0072] The ECU 512 is coupled to the bridge rectifier 508 and the
rechargeable battery 510. The ECU 512 can be configured to measure
the AC voltage of the output of the generator motor 506, which is
directly proportional to the revolutions per minute (RPM) of the
engine 504, and compares it to the DC power output of the bridge
rectifier 508. The ECU 512 can control the throttle of the engine
504 to cause the DC power output of the bridge rectifier 508 to
increase or decrease as the load changes, e.g., a load of one or
more electric motors 516 or one or more of loads 518, 526, 528, and
536. In one example, the ECU 512 can be an Arduino.RTM. MEGA 2560
Board R3, available from China. In various embodiments, a load of
one or more electric motors 516 can change as the ESC 514 changes
an amount of power provided to the electric motors 516. For
example, if a user inputs to increase the power provided to the
electric motors 516 subsequently causing the ESC 514 to provide
more power to the electric motors 516, then the ECU 512 can
increase the throttle of the engine 504 to cause the production of
more power to provide to the electronic motors 516.
[0073] The ECU 512 can function to maintain voltage output of loads
by reading the sensed analog voltage, converting these to ADC
counts, comparing the count to that corresponding to a desired
voltage, and increasing or decreasing the throttle of the engine
504 according to the programmed gain if the result is outside of
the dead band.
[0074] In one example, the hybrid generator system 500 can provide
about 1,800 watts of continuous power, 10,000 watts of
instantaneous power (e.g., 6S with 16,000 mAh pulse battery) and
has a 1,500 Wh/kg gasoline conversion rate. In one example, the
hybrid generator system 500 has dimensions of about 12'' by 12'' by
12'' and a weight of about 8 lbs.
[0075] FIG. 6 depicts a side perspective view of a hybrid generator
system 500. FIG. 7A depicts a side view of a hybrid generator 500.
FIG. 7B depicts an exploded side view of a hybrid generator 500.
The hybrid generator system 500 includes an engine 504 coupled to
generator motor 506. In one embodiment, the engine 504 includes a
coupling/cooling device 602 which provides coupling of the shaft of
the generator motor 506 to the shaft of engine 504 and also
provides cooling with sink fins 604. For example, FIGS. 7A and 7B,
show in further detail one embodiment of coupling/cooling device
602, which includes coupling/fan 702 with set screws 704 that
couple shaft 706 of generator motor 506 and shaft 708 of engine
504. Coupling/cooling device 602 may also include rubber coupling
ring 2202 (FIG. 22A).
[0076] In various embodiments, the hybrid generator system 500
includes components to facilitate transfer of heat away from the
hybrid generator system 500 and/or is integrated within a UAV to
increase airflow over components that produce heat. For example,
the hybrid generator system 500 can include cooling fins on
specific components, e.g. the rectifier, to transfer heat away from
the hybrid generator system. In various implementations, the hybrid
generator system 500 includes components and is integrated within a
UAV to cause heat to be transferred towards the exterior of the
UAV.
[0077] In various embodiments, the hybrid generator system 500
and/or a UAV integrating the hybrid generator system 500 is
configured to allow 406 cubic feet per minute of airflow across at
least one component of the hybrid generator system 500. An engine
504 of the hybrid generator system 500 can be run at an operating
temperature 150.degree. C. and if an ambient temperature in which
the hybrid generator system 10, in order to remove heat generated
by the engine 506, an airflow of 406 cubic feet per minute is
achieved across at least the engine 506. Further in various
embodiments, the engine 506 is operated at 16.5 Horsepower and
generates 49.2 kW of waste heat, e.g. each head of the engine
produces 24.6 kW of waste heat. In various embodiments, engine
heads of the engine 506 of the hybrid generator system 500 are
coupled to electric ducted fans to concentrate airflow over the
engine heads. For example, 406 cubic feet per minute airflow can be
achieved over engine heads of the engine 506 using electric ducted
fans.
[0078] In various embodiments, the hybrid generator system 500 is
integrated as part of a UAV using a dual vibration damping system.
An engine 506 of the hybrid generator system can utilize couplings
to serve as dual vibration damping systems. In one example, the
engine 506 produces a mean torque of 1.68 Nm at 10,000 RPM. In the
various embodiments, a urethane coupling is used to couple, at
least part of, the hybrid generator system 500 to a UAV. Further in
the one example, the urethane coupling can have a durometer value
of between 90 A to 75 D. Example urethane couplings used to secure,
at least part of, the hybrid generator system 500 to a UAV include
L42 Urethane, L100 Urethane, L167 Urethane, and L315 Urethane.
Urethane couplings used to secure, at least part of, the hybrid
generator system 500 to a UAV can have a tensile strength between
20 MPa and 62.0 MPa, between 270 to 800% elongation at breaking, a
modulus between 2.8 MPa and 32 MPa, an abrasion index between 110%
and 435%, and a tear strength split between 12.2 kN/m and 192.2
kN/m.
[0079] In some examples, the engine 504, FIGS. 6 and 7, can also
include a fly wheel 606 which reduces mechanical noise and/or
engine vibration. In some examples, the engine 504 can include a
Hall Effect sensor 710, FIG. 7A, and Hall Effect magnet coupled to
fly wheel 606 as shown. In one example, Hall-effect sensor 710 may
be available from RCexl Min Tachometer.RTM., Zhejiang Province,
China.
[0080] When engine 504 is operational, fly wheel 606 spins and
generates a voltage which is directly proportional to the
revolutions per minute of fly wheel 606. This voltage is measured
by Hall-effect sensor 710 and is input into an ECU 512. The ECU 512
compares the measured voltage to the voltage output by generator
motor 506. ECU 512 will then control the throttle of either or both
the generator motor 506 and the engine 504 to increase or decrease
the voltage as needed to supply power to one or more of loads 518,
526, 528, and/or 536 or one or more rotor motors 516.
[0081] The engine 504 may also include a starter motor 608, servo
610, muffler 612, and vibrational mount 614.
[0082] FIG. 8 is a perspective view of a hybrid generator system
500. The hybrid generator system 500 includes a motor 504 and
generator motor 506 coupled to a bridge rectifier 508.
[0083] FIG. 9 is a perspective view of a UAV 900 integrated with a
hybrid generator system 500. The UAV 900 includes six rotor motors
516 each coupled to propellers 902, however it is appreciated that
a UAV integrated with a hybrid generator system 500 can include
more or less rotor motors and propeller. The UAV 900 can include a
Px4 flight controller manufactured by Pixhawk.RTM..
[0084] In one embodiment, engine 504, as shown in FIGS. 4-9 may be
started using an electric starter 616. Fuel source 502, as shown in
FIG. 5 (also shown in FIG. 9) delivers fuel to engine 504 to spin
its rotor shaft directly coupled to generator motor 506 as shown in
FIG. 7 and applies a force to generator motor 506. The spinning of
generator motor 506 generates electricity and the power generated
by motor generator 506 is proportional to the power applied by
shaft of engine 504. Preferably, a target rotational speed of
generator motor 506 is determined based on the KV (rpm/V) of
generator motor 506. For example, if a target voltage of 25 Volt DC
is desired, the rating of generator motor 506 would be about 400
KV. The rotational speed of the engine 504 may be determined by the
following equations:
RPM=KV (RPM/Volt).times.Target Voltage (VDC) (1)
RPM=400 KV.times.25 VDC (2)
RPM=10,000 (3)
[0085] In this example, for generator motor 506 to generate 25 VDC
output, the shaft of generator motor 506 coupled to the shaft of
engine 504 needs to spin at about 10,000 RPM.
[0086] As the load, e.g., one or more motors 516 or one or more of
loads 518, 526, 528, and/or 536, is applied to the output of
generator motor 506, the voltage output of the hybrid generator
system 500 will drop which will cause the speed of engine 504 and
generator motor 506 to be reduced. In this case, ECU 512 can be
used to help regulate the throttle of engine 504 to maintain a
consistent output voltage that varies with loads. ECU 512 can act
like a standard governor for gasoline engines but instead of
regulating an RPM, it can regulate a target voltage output of
either or both a bridge rectifier and a generator motor 506 based
on a closed loop feedback controller.
[0087] Power output from generator motor 506 can be in the form of
alternating current (AC) which needs to be rectified by bridge
rectifier 508. Bridge rectifier 508 can convert the AC power into
direct current (DC) power, as discussed above. In various
embodiments, the output power of the hybrid generator system 500
can be placed in a "serial hybrid" configuration, where the
generator power output by generator motor 506 may be available to
charge the rechargeable battery 510 or provide power to another
external load.
[0088] In operation, there can be at least two available power
sources when the hybrid generator system 500 is functioning. A
primary source can be from the generator motor 506 through directly
from the bridge rectifier and a secondary power source can be from
the rechargeable battery 510. Therefore, a combination of
continuous power availability and high peak power availability is
provided, which may be especially well-suited for UAV applications
or a portable generator applications. In cases where either primary
(generator motor 506) power source is not available, system 500 can
still continue to operate for a short period of time using power
from rechargeable battery 510 allowing a UAV to sustain safety
strategy, such as an emergency landing.
[0089] When hybrid generator system 500 is used for UAVs, the
following conditions can be met to operate the UAV effectively and
efficiently: 1) the total continuous power (watts) can be greater
than power required to sustain UAV flight, 2) the power required to
sustain a UAV flight is a function of the total weight of the
vehicle, the total weight of the hybrid engine, the total weight of
fuel, and the total weight of the payload), where:
Total Weight (gram)=vehicle dry weight+engine 504 weight+fuel
weight+payload (4)
and, 3) based on the vehicle configuration and aerodynamics, a
particular vehicle will have an efficiency rating (grams/watt) of
11, where:
Total Power Required to Fly=.eta..times.Weight (gram) (5)
[0090] In cases where the power required to sustain flight is
greater than the available continuous power, the available power or
total energy is preferably based on the size and configuration of
the rechargeable battery 510. A configuration of the rechargeable
battery 510 can be based on a cell configuration of the
rechargeable battery 510, a cell rating of the rechargeable battery
510, and/or total mAh of the rechargeable battery 510. In one
example, for a 6S, 16000 mAh, 25C battery pack, the total energy is
determined by the following equations:
Total Energy=Voltage.times.mAh=25 VDC (6S).times.16000 mAh=400
Watt*Hours (6)
Peak Power Availability=Voltage.times.mAh.times.C Rating=25
VDC.times.16000 mAh.times.25 C 10,400 Watts (7)
Total Peak Time=400 Watt*Hours/10,400 Watts=138.4 secs (8)
Further in the one example, the rechargeable battery 510 will be
able to provide 10,400 Watts of power for 138.4 seconds in the
event of primary power failure from engine 504. Additionally, the
rechargeable battery 510 may be able to provide up to 10,400 Watts
of available power for flight or payload needs instantaneous peak
power for short periods of time needed for aggressive
maneuvers.
[0091] The result is hybrid generator system 500 when coupled to a
UAV efficiently and effectively provides power to fly and maneuver
the UAV for extended periods of time with higher payloads than
conventional multi-rotor UAVs. In one example, the hybrid generator
system 500 can provide a loaded (3 lb. load) flight time of up to
about 2 hours 5 mins, and an unloaded flight time of about 2 hours
and 35 mins Moreover, in the event that the fuel source runs out or
the engine 504 and/or he generator motor 506 malfunctions, the
hybrid generator system 500 can use the rechargeable battery 510 to
provide enough power to allow the UAV to perform a safe landing. In
various embodiments, the rechargeable battery 510 can provide
instantaneous peak power to a UAV for aggressive maneuvers, for
avoiding objects, or threats, and the like.
[0092] In various embodiments, the hybrid generator system 500 can
provide a reliable, efficient, lightweight, portable generator
system which can be used in both commercial and residential
applications to provide power at remote locations away from a power
grid and for a micro-grid generator, or an ultra-micro-grid
generator.
[0093] In various embodiments, the hybrid generator system 500 can
be used for an applicable application, e.g. robotics, portable
generators, micro-grids and ultra-micro-grids, and the like, where
an efficient high energy density power source is required and where
a fuel source is readily available to convert hydrocarbon fuels
into useable electric power. The hybrid generator system 500 has
been shown to be significantly more energy efficient than various
forms of rechargeable batteries (Lithium Ion, Lithium Polymer,
Lithium Sulfur) and even Fuel Cell technologies typically used in
conventional UAVs.
[0094] FIG. 10 depicts a graph comparing energy density of
different UAV power sources. In various embodiments, the hybrid
generator system 500 can use conventional gasoline which is readily
available at low cost and provide about 1,500 Wh/kg of power for
UAV applications, e.g., as indicated at 1002 in FIG. 6.
Conventional UAVs which rely entirely on batteries can provide a
maximum energy density of about 1,000 Wh/kg when using an energy
high density fuel cell technology, indicated at 1004 about 400
Wh/kg when using lithium sulfur batteries, indicated at 1006, and
only about 200 Wh/kg when using a LiPo battery, indicated at
1008.
[0095] FIG. 11 depicts a graph 1104 of market potential for UAVs
against flight time for an example two plus hours of flight time
hybrid generator system 500 of one or more when coupled to a UAV is
able to achieve and an example of the total market potential vs.
endurance for the hybrid generator system 500 for UAVs.
[0096] In various embodiments, the hybrid generator power systems
500 can be integrated as part of a UAV or similar type aerial
robotic vehicle to perform as a portable flying generator using the
primary source of power to sustain flight of the UAV and then act
as a primary power source of power when the UAV has reached its
destination and is not in flight. For example, when a UAV which
incorporates hybrid system 10, e.g., UAV 900, FIG. 9, is not in
flight, the available power generated by hybrid system can be
transferred to one or more of external loads 518, 526, 528, and/or
536 such that hybrid generator system 500 operates as a portable
generator. hybrid system generator 500 can provide continuous peak
power generation capability to provide power at remote and often
difficult to reach locations. In the "non-flight portable generator
mode", hybrid system 500 can divert the available power generation
capability towards external one or more of loads 518, 526, 528,
and/or 536. Depending on the power requirements, one or more of
DC-to-AC inverters 522, 532 may be used to convert DC voltage to
standard AC power (120 VAC or 240 VAC).
[0097] In operation, hybrid generator system 500 coupled to a UAV,
such as UAV 900, FIG. 9, will be able to traverse from location to
location using aerial flight, land, and switch on the power
generator to convert fuel into power.
[0098] FIG. 12 shows an example flight pattern of a UAV with a
hybrid generator system 500. In the example flight pattern shown in
FIG. 12, the UAV 900, with hybrid system 500 coupled thereto,
begins at location A loaded with fuel ready to fly. The UAV 900
then travels from location A to location B and lands at location B.
The UAV 900 then uses hybrid system 500 to generate power for local
use at location B, thereby acting as a portable flying generator.
When power is no longer needed, the UAV 900 returns back to
location A and awaits instructions for the next task.
[0099] In various embodiments, the UAV 900 uses the power provided
by hybrid generator system 500 to travel from an initial location
to a remote location, fly, land, and then generate power at the
remote location. Upon completion of the task, the UAV 900 is ready
to accept commands for its new task. All of this can be performed
manually or through an autonomous/automated process. In various
embodiments, the UAV 900 with hybrid generator system 500 can be
used in an applicable application where carrying fuel and a local
power generator are needed. Thus, the UAV 900 with a hybrid
generator system 500 eliminates the need to carry both fuel and a
generator to a remote location. The UAV 900 with a hybrid generator
system 500 is capable of powering both the vehicle when in flight,
and when not in flight can provide the same amount of available
power to external loads. This may be useful in situations where
power is needed for the armed forces in the field, in humanitarian
or disaster relief situations where transportation of a generator
and fuel is challenging, or in situations where there is a request
for power that is no longer available.
[0100] FIG. 13 depicts a diagram of another system for a hybrid
generator system 500 with detachable subsystems. FIG. 14A depicts a
diagram of a hybrid generator system 500 with detachable subsystems
integrated as part of a UAV. FIG. 14B depicts a diagram of a hybrid
generator system 500 with detachable subsystems integrated as part
of a ground robot. In various embodiments, a tether line 1302 is
coupled to the DC output of bride rectifier 508 and rechargeable
battery 510 of a hybrid control system 500. The tether line 1302
can provide DC power output to a tether controller 1304. The tether
controller 1304 is coupled between a tether cable 1306 and a ground
or aerial robot 1308. In operation, as discussed in further detail
below, the hybrid generator system 500 provides tethered power to
the ground or aerial robot 1308 with the similar output
capabilities as discussed above with one or more of the Figs. in
this paper.
[0101] The system shown in FIG. 13 can include additional
detachable components 1310 integrated as part of the system, e.g.,
data storage equipment 1312, communications equipment 1314,
external load sensors 1316, additional hardware 1318, and various
miscellaneous equipment 1320 that can be coupled via data tether
1322 to tether controller 1304.
[0102] In one example of operation of the system shown in FIG. 13,
the system may be configured as part of a flying robot or UAV, such
as flying robot or UAV 1402, FIG. 14, or as ground robot 1404.
Portable tethered robotic system 1408 starts a mission at location
A. All or an applicable combination of the subsystems and ground,
the tether controller, ground/aerial robot 1308 can be powered by
the hybrid generator system 500. The Portable tethered robotic
system 1408 travels either by ground, e.g., using ground robot 1404
powered by hybrid generator system 500 or by air using flying robot
or UAV 1402 powered by hybrid generator system 500 to desired
remote location B. At location B, portable tethered robotic system
1408 configured as flying robot 1402 or ground robot 1404 can
autonomously decouple hybrid generator system 500 and/or detachable
subsystem 1310, indicated at 1406, which remain detached while
ground robot 1404 or flying robot or UAV 1402 are operational. When
flying robot or UAV 1402 is needed at location B, indicated at
1412, flying robot or UAV 1402 can be operated using power provided
by hybrid generator system coupled to tether cable 1306. When
flying robot or UAV 1402 no longer has hybrid generator system 500
and/or additional components 1310 attached thereto, it is
significantly lighter and can be in flight for a longer period of
time. In one example, flying robot or UAV 1402 can take off and
remain in a hovering position remotely for extended periods of time
using the power provided by hybrid generator system 500.
[0103] Similarly, when ground robot 1404 is needed at location B,
indicated at 1410, it may be powered by hybrid generator system 500
coupled to tether line 1306 and will also be significantly lighter
without hybrid generator system 500 and/or additional components
1310 attached thereto. Ground robot 1404 can also be used for
extended periods of time using the power provide by hybrid
generator system 500.
[0104] FIG. 15 shows a ground robot 1502 with a detachable flying
pack in operation. The detachable flying pack 1504 includes hybrid
generator system 500. The detachable flying pack is coupled to the
ground robot 1502 of one or more embodiments. The hybrid generator
system 500 is embedded within the ground robot 1502. The ground
robot 1502 is detachable from the flying pack 1504. With such a
design, a majority of the capability is embedded deep within the
ground robot 1502 which can operate 100% independently of the
flying pack 1504. When the ground robot 1502 is attached to the
flying pack 1504, the flying pack 1504 is powered from hybrid
generator system 500 embedded in the ground robot 1502 and the
flying pack 1504 provides flight. The ground robot 1502 platform
can be a leg wheel or threaded base motion.
[0105] In one embodiment, the ground robot 1502 may include the
detachable flying pack 1504 and the hybrid generator system 500
coupled thereto as shown in FIG. 15. In this example, the ground
robot 1502 is a wheel-based robot as shown by wheels 1506. In this
example, the hybrid generator system 10, includes fuel source 502,
engine 504, generator motor 506, bridge rectifier 508, rechargeable
battery 20, ECU 512, and optional inverters 522 and 532, as
discussed above with reference to one or more Figs. in this paper.
The hybrid generator system 500 also preferably includes data
storage equipment 1312, communications equipment 1314, external
load sensors 1316, additional hardware 1318, and miscellaneous
communications 1320 coupled to data line 1322 as shown. The flying
pack 1504 is preferably, an aerial robotic platform such as a fixed
wing, single rotor or multi rotor, aerial device, or similar type
aerial device.
[0106] In one embodiment, the ground robot 1502 and the aerial
flying pack 1504 are configured as a single unit. Power is
delivered the from hybrid generator system 500 and is used to
provide power to flying pack 1504, so that ground robot 1502 and
flying pack 1504 can fly from location A to location B. At location
B, ground robot 1506 detaches from flying pack 1504, indicated at
1508, and is able to maneuver and operate independently from flying
pack 1504. Hybrid generator system 500 is embedded in ground robot
1502 such that ground robot 1506 is able to be independently
powered from flying pack 1504. Upon completion of the ground
mission, ground robot 1502 is able to reattached itself to flying
pack 1504 and return to location A. All of the above operations can
be manual, semi-autonomous, or fully autonomous.
[0107] In one embodiment, flying pack 1504 can traverse to a remote
location and deliver ground robot 1502. At the desired location,
there is no need for flying pack 1504 so it can be left behind so
that ground robot 1502 can complete its mission without having to
carry flying pack 1504 as its payload. This may be useful for
traversing difficult and challenging terrains, remote locations,
and in situations where it is challenging to transport ground robot
1502 to the location. Exemplary applications may include remote
mine destinations, remote surveillance and reconnaissance, and
package delivery services where flying pack 1504 cannot land near
an intended destination. In these examples, a designated safe drop
zone for flying pack can be used and local delivery is completed by
ground robot 1502 to the destination.
[0108] In various embodiments, then a mission is complete, ground
robot 1404 or flying robot or UAV 1402 can be autonomously coupled
back to hybrid generator system 500. Additional detachable
components 1310 can auto be autonomously coupled back hybrid
generator system 500. Portable tethered robotic system 1408 with a
hybrid generator system 500 configured a flying robot or UAV 1402
or ground robot 1404 then returns to location A using the power
provided by hybrid generator system 500.
[0109] The result is portable tethered robotic system 1408 with a
hybrid generator system 500 is able to efficiently transport ground
robot 1404 or flying robot or UAV 1402 to remote locations,
automatically decouple ground robot 1404 or flying robot or UAV
1402, and effectively operate the flying robot 1402 or ground robot
1404 using tether power where it may be beneficial to maximize the
operation time of the ground robot 1402 or flying robot or UAV
1404. System 1408 provides modular detachable tethering which may
be effective in reducing the weight of the tethered ground or
aerial robot thereby reducing its power requirements significantly.
This allows the aerial robot or UAV or ground robot to operate for
significantly longer periods of time when compared to the original
capability where the vehicle components are attached and the
vehicle needs to sustain motion. System 1408 eliminates the need to
assemble a generator, robot and tether at remote locations and
therefore saves time, resources, and expense. Useful applications
of system 1408 may include, inter alia, remote sensing, offensive
or defensive military applications and/or communications
networking, or multi-vehicle cooperative environments, and the
like.
[0110] FIG. 16 shows a control system of a hybrid generator system.
The hybrid generator system includes a power plant 1602 coupled to
an ignition module 1604. The ignition module 1604 functions to
start the power plant 1602 by providing a physical spark to the
power plant 1604. The ignition module 1604 is coupled to an
ignition battery eliminator circuit (IBEC) 1606. The IBEC 1606
functions to power the ignition module 1604.
[0111] In some examples, the ignition module 1604 is powered
directly from the output of the bridge rectifier through a DC/DC
converter rather than using the IBEC 1606. For instance, powering
the ignition module 1604 by the bridge rectifier output can be used
for power generation systems producing at least about 10 kW of
power.
[0112] The power plant 1602 is configured to provide power. The
power plant 1602 includes an engine and a generator. The power
plant is controlled by the ECU 1608. The ECU 1608 is coupled to the
power plant through a throttle servo. The ECU 1608 can operate the
throttle servo to control a throttle of an engine to cause the
power plant 1602 to either increase or decrease an amount of
produced power. The ECU 1608 is coupled to a voltage divider 1610.
Through the voltage divider 1610, the ECU can determine an amount
of power the ECU 1608 is generating to determine whether to
increase, decrease, or keep a throttle of an engine constant.
[0113] The power plant is coupled to a power distribution board
1612. The power distribution board 1612 can distribute power
generated by the power plant 1602 to either or both a battery pack
1614 and a load/vehicle 1616. The power distribution board 1612 is
coupled to a battery eliminator circuit (BEC) 1618. The BEC 1618
provides power to the ECU 1608 and a receiver 1620. The receiver
1620 controls the IBEC 1606 and functions to cause the IBEC 1606 to
power the ignition module 1604. The receiver 1620 also sends
information to the ECU 1608 used in controlling a throttle of an
engine of the power plant 1602. The receiver 1620 to the ECU
information related to a throttle position of a throttle of an
engine and a mode in which the hybrid generation system is
operating. In some examples, when the IBEC is not used, the
receiver 1620 is used to directly enable or disable the ignition
module 1604.
[0114] FIG. 17 shows a top perspective view of a top portion 1700
of a drone powered through a hybrid generator system. The top
portion 1700 of the drone shown in FIG. 13 includes six rotors
1702-1 . . . 1702-6 (hereinafter "rotors 1702"). The rotors 1702
are caused to spin by corresponding motors 1704-1 . . . 1704-6
(hereinafter "motors 1704"). The motors 1704 can be powered through
a hybrid generator system. The top portion 1700 of a drone includes
a top surface 1706. Edges of the top surface 1706 can be curved to
reduce air drag and improve aerodynamic performance of the drone.
The top surface includes an opening 1708 through which air can flow
to aid in dissipating heat away from at least a portion of a hybrid
generator system. In various embodiments, at least a portion of an
air filter is exposed through the opening 1708.
[0115] FIG. 18 shows a top perspective view of a bottom portion
1800 of a drone powered through a hybrid generator system 500. The
hybrid generator system 500 includes an engine 504 and a generator
motor 506 to provide power to motors 1704. The rotor motors 1704
and corresponding rotors 1702 are positioned away from a main body
of a bottom portion 1800 of the drone through arms 1802-1 . . .
1802-6 (hereinafter "arms 1802"). An outer surface of the bottom
portion of the bottom portion 1800 of the drone and/or the arms
1802 can have edges that are curved to reduce air drag and improve
aerodynamic performance of the drone.
[0116] FIG. 19 shows a top view of a bottom portion 1800 of a drone
powered through a hybrid generator system 500. The rotor motors
1704 and corresponding rotors 1702 are positioned away from a main
body of a bottom portion 1800 of the drone through arms 1802. An
outer surface of the bottom portion of the bottom portion 1800 of
the drone and/or the arms 1802 can have edges that are curved to
reduce air drag and improve aerodynamic performance of the
drone.
[0117] FIG. 20 shows a side perspective view of a hybrid generator
system 500. The hybrid generator system 500 shown in FIG. 16 is
capable of providing 1.8 kW of power. The hybrid generator system
500 include an engine 504 coupled to a generator motor 506. The
engine 504 can provide approximately 3 horsepower. The generator
motor 506 functions to generate AC output power using mechanical
power generated by the engine 504.
[0118] FIG. 21 shows a side perspective view of a hybrid generator
system 500. The hybrid generator system 500 shown in FIG. 17 is
capable of providing 10 kW of power. The hybrid generator system
500 include an engine 504 coupled to a generator motor. The engine
504 can provide approximately 15-16.5 horsepower. The generator
motor functions to generate AC output power using mechanical power
generated by the engine 504.
[0119] Further description of UAVs and hybrid generator systems can
be found in U.S. application Ser. No. 14/942,600, the contents of
which are incorporated here by reference in their entirety.
[0120] In some examples, the engine 504 can include features that
enable the engine to operate with high power density. The engine
504 can be a two-stroke engine having a high power-to-weight ratio.
The engine 504 can embody a simply design with a small number of
moving parts such that the engine is small and light, thus
contributing to the high power-to-weight ratio of the engine. In a
specific example, the engine has an energy density of 1 kW/kg
(kilowatt per kilogram) and generates about 10 kg of lift for every
kilowatt of power generated by the engine. In some examples, the
engine 504 can be coupled to a brushless DC motor or a permanent
magnet synchronous motor, which can contribute to achieving a high
power density of the engine. For instance, a brushless motor is
efficient and reliable, and is generally not prone to sparking,
thus reducing the risk of electromagnetic interference (EMI) from
the engine.
[0121] In some examples, the engine 504 is mounted on the UAV via a
vibration isolation system that enables sensitive components of the
UAV and data center to be isolated from vibrations generated by the
engine. Sensitive components of the UAV can include, e.g., an
inertial measurement unit such as Pixhawk, a compass, a global
positioning system (GPS), or other components. Sensitive components
of the data center can include, e.g., processors, data storage
devices, wireless communications components, or other
components.
[0122] In some examples, the vibration isolation system can include
vibration damping mounts that attach the engine to the frame of the
UAV. The vibration damping mounts allow for the engine 504 to
oscillate independently from the frame of the UAV, thus preventing
vibrations from being transmitted from the engine to other
components of the UAV. The vibration damping mounts can be formed
from a robust, energy absorbing material such as rubber, that can
absorb the mechanical energy generated by the motion of the engine
without tearing or ripping, thus preventing the mechanical energy
from being transferred to the rest of the UAV. In some examples,
the vibration damping mounts can be formed of two layers of rubber
dampers joined together rigidly with a spacer. The length of the
spacer can be adjusted to achieve a desired stiffness for the
mount. The hardness of the rubber can be adjusted to achieve
desired damping characteristics in order to absorb vibrational
energy.
[0123] Referring to FIG. 22A, in some examples, the engine 504 and
the generator motor 506 are directly coupled through a precise and
robust connection, e.g., through a rigid metal coupling or a
urethane coupling 704. For instance, the rigid metal coupling can
include bolted aluminum plates that are stable against operation at
high rpm, pulse loading, and shocks. In particular, the generator
motor 506 includes a generator rotor 706 and a generator stator 708
housed in a generator body 2202. The generator rotor 706 is
attached to the generator body 2202 by generator bearings 2204. The
generator rotor 706 is coupled to an engine shaft 606 via the
coupling 704. Precision coupling between the engine 504 and the
generator motor 506 can be achieved by using precisely machined
parts and balancing the weight and support of the rotating
components of the generator motor 506, which in turn reduces
internal stresses. Alignment of the rotor of the generator with the
engine shaft can also help to achieve precision coupling.
Misalignment between the rotor and the engine shaft can cause
imbalances that can reduce efficiency and potentially lead to
premature failure. In some examples, alignment of the rotor with
the engine shaft can be achieved using precise indicators and
fixtures. Precision coupling can be maintained by cooling the
engine 504 and generator motor 506, by reducing external stresses,
and by running the engine 504 and generator motor 506 under steady
conditions, to the extent possible. For instance, the vibration
isolation mounts allow external stresses on the engine 504 to be
reduced or substantially eliminated, assisting in achieving
precision direct coupling.
[0124] Direct coupling can contribute to the reliability of the
first power system, which in turn enables the hybrid generator
system to operate continuously for long periods of time at high
power. In addition, direct coupling can contribute to the
durability of the first power system, thus helping to reduce
mechanical creep and fatigue even over many engine cycles, such as
millions of engine cycles. In some examples, the engine is
mechanically isolated from the frame of the UAV by the vibration
isolation system and thus experiences minimal external forces, so
the direct coupling between the engine and the generator motor can
be implemented by taking into account only internal stresses.
[0125] Direct coupling between the engine 504 and the generator
motor 506 can enable the first power system to be a compact,
lightweight power system having a small form factor. A compact and
lightweight power system can be readily integrated into the
UAV.
[0126] Referring to FIG. 22B, in some examples, a frameless or
bearing-less generator 608 can be used instead of a urethane
coupling between the generator motor 506 and the engine 504. For
instance, the bearings (2204 in FIG. 22A) on the generator can be
removed and the generator rotor 706 can be directly mated to the
engine shaft 606. The generator stator 708 can be fixed to a frame
610 of the engine 516. This configuration prevents
over-constraining the generator with a coupling while providing a
small form factor and reduced weight and complexity.
[0127] In some examples, compliant or flexible couplings can be
provided as splined shafts, CV joints, UV joints, and/or for other
UAV components. Such compliant couplings can be relevant for use
with larger UAV systems, such as UAV systems sized to carry
passengers. Compliant or flexible coupling reduce the requirement
for precise alignment of the engine and generator shafts.
[0128] In some examples, the generator motor 506 includes a
flywheel that provides a large rotational moment of inertia. A
large rotational inertia can result in reduced torque spikes and
smooth power output, thus reducing wear on the coupling between the
engine 504 and the generator motor 506 and contributing to the
reliability of the first power system. In some examples, the
generator, when mated directly to the engine 504, acts as a
flywheel. In some examples, the flywheel is a distinct component,
e.g., if the generator does not provide enough rotary inertia.
[0129] In some examples, design criteria are set to provide good
pairing between the engine 504 and the generator motor 506. The
power band of a motor is typically limited to a small range. This
power band can be used to identify an RPM (revolutions per minute)
range within which to operate under most flight conditions. Based
on the identified RPM range, a generator can be selected that has a
motor constant (kV) that is able to provide the appropriate voltage
for the propulsion system (e.g., the rotors). The selection of an
appropriate generator helps to ensure that the voltage out of the
generator will not drop as the load increases. For instance, if the
engine has maximum power at 6500 RPM, and a 50 V system is desired
for propulsion, then a generator can be selected that has a kV of
130.
[0130] In some examples, exhaust pipes can be designed to
positively affect the efficiency of the engine 504. Exhaust pipes
serve as an expansion chamber for exhaust from the engine, thus
improving the volumetric efficiency of the engine. The shape of the
exhaust pipes can be tuned to guide air back into the combustion
chamber based on the resonance of the system. In some examples, the
carburetor can also be tuned based on operating parameters of the
engine, such as temperature or other parameters. For instance, the
carburetor can be tuned to allow a desired amount of fuel into the
engine, thus enabling a target fuel to air ratio to be reached in
order to achieve a good combustion reaction in the engine. In
addition, the throttle body can be designed to control fuel
injection and/or timing in order to further improve engine
output.
[0131] In some examples, the throttle of the engine can be
regulated in order to achieve a desired engine performance. For
instance, when the voltage of the system drops under a load, the
throttle is increased; when the voltage of the system becomes too
high, the throttle is decreased. The bus voltage can be regulated
and a feedback control loop used to control the throttle position.
In some examples, the current flow into the battery can be
monitored with the goal of controlling the charge of the battery
and the propulsion voltage. In some examples, feed forward controls
can be provided such that the engine can anticipate upcoming
changes in load (e.g., based on a mission plan and/or based on the
load drawn by the motor) and preemptively compensates for the
anticipated changes. Feed forward controls enable the engine to
respond to changes in load with less lag. In some examples, the
engine can be controlled to charge the battery according to a
pre-specified schedule, e.g., to maximize battery life, in
anticipation of loads (e.g., loads forecast in a mission plan), or
another goal. Throttle regulation can help keep the battery fully
charged, helping to ensure that the system can run at a desired
voltage and helping to ensure that backup power is available.
[0132] In some examples, ultra-capacitors can be incorporated into
the hybrid generator system in order to allow the hybrid generator
system to respond quickly to changing power demands. For instance,
ultra-capacitors can be used in conjunction with one or more
rechargeable batteries to provide a lightweight system capable of
rapid response and smooth, reliable power.
[0133] In some examples, thermal management strategies can be
employed in order to actively or passively cool components of the
hybrid generator system. High power dense components tend to
overheat, e.g., because thermal dissipation is usually proportional
to surface area. In addition, internal combustion is an inherently
inefficient process, which creates heat.
[0134] Active cooling strategies can include fans, such as a
centrifugal fan. The centrifugal fan can be coupled to the engine
shaft so that the fan spins at the same RPM as the engine, thus
producing significant air flow. The centrifugal fan can be
positioned such that the air flow is directed over certain
components of the engine, e.g., the hottest parts of the engine,
such as the cylinder heads. Air flow generated by the flying motion
of the UAV can also be used to cool the hybrid generator system.
For instance, air pushed by the rotors of the UAV (referred to as
propwash) can be used to cool components of the hybrid generator
system. Passive cooling strategies can used alone or in combination
with active cooling strategies in order to cool components of the
hybrid generator system. In some examples, one or more components
of the hybrid generator system can be positioned in contact with
dissipative heat sinks, thus reducing the operating temperature of
the components. For instance, the frame of the UAV can be formed of
a thermally conductive material, such as aluminum, which can act as
a heat sink. Referring to FIG. 22, in some examples, fins 2302 can
be formed on the engine (e.g., on one or more of the cylinder heads
of the engine) to increase the convective surface area of the
engine, thus enabling increased heat transfer. In some examples,
the hybrid generator system can be configured such that certain
components are selectively exposed to ambient air or to air flow
generated by the flying motion of the UAV in order to further cool
the components.
[0135] In some examples, the materials of the hybrid generator
system 10, the UAV, and/or the data center components can be
lightweight. For instance, materials with a high strength to weight
ratio can be used to reduce weight. Example materials can include
aluminum or high strength aluminum alloys (e.g., 7075 alloy),
carbon fiber based materials, or other materials. Component design
can also contribute to weight reduction. For instance, components
can be designed to increase the stiffness and reduce the amount of
material used for the components. In some examples, components can
be designed such that material that is not relevant for the
functioning of the component is removed, thus further reducing the
weight of the component.
[0136] Other embodiments are within the scope of the following
claims.
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