U.S. patent application number 15/002786 was filed with the patent office on 2017-07-27 for electrohydraulic dynamic spool position control for a proportional valve in a work vehicle.
The applicant listed for this patent is DEERE & COMPANY. Invention is credited to Calin Raszga, Daryl Rober.
Application Number | 20170208754 15/002786 |
Document ID | / |
Family ID | 57914724 |
Filed Date | 2017-07-27 |
United States Patent
Application |
20170208754 |
Kind Code |
A1 |
Raszga; Calin ; et
al. |
July 27, 2017 |
ELECTROHYDRAULIC DYNAMIC SPOOL POSITION CONTROL FOR A PROPORTIONAL
VALVE IN A WORK VEHICLE
Abstract
A work machine to cut timber including a control system, a
felling head, a hydraulic motor configured to adjust the position
of the felling head, and a spool valve operatively connected to the
hydraulic motor, the spool valve being configured to move the
felling head responsively through operation of the hydraulic motor.
A machine controller coupled to the operator controller and the
spool valve executes stored program instructions to generate a
first control signal responsive to an operator control signal
provided by the operator controller, generate a second control
signal as a function of the generated first control signal, adjust
a position of the spool of the spool valve in response to a
concurrent receipt of the first control signal and the second
control signal by the first proportional control valve and the
second proportional control valve to move the felling head through
operation of the hydraulic motor.
Inventors: |
Raszga; Calin; (Dubuque,
IA) ; Rober; Daryl; (Asbury, IA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DEERE & COMPANY |
MOLINE |
IL |
US |
|
|
Family ID: |
57914724 |
Appl. No.: |
15/002786 |
Filed: |
January 21, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F15B 2211/505 20130101;
F15B 13/0433 20130101; F15B 11/08 20130101; F15B 13/044 20130101;
F15B 13/0407 20130101; G05B 19/46 20130101; F16K 31/426 20130101;
F15B 13/0402 20130101; G05B 2219/41301 20130101; A01G 23/091
20130101 |
International
Class: |
A01G 23/091 20060101
A01G023/091; F16K 31/42 20060101 F16K031/42; F15B 13/044 20060101
F15B013/044; F15B 11/08 20060101 F15B011/08; F15B 13/04 20060101
F15B013/04 |
Claims
1. A method of controlling a piloted spool valve with a first
proportional pilot valve and a second proportional pilot valve, the
method comprising: generating a first control signal for moving a
spool of the piloted spool valve in a first direction; generating a
second control signal as a function of the generated first control
signal, the second control signal for moving the spool of the
piloted spool valve in a second direction, the second direction
being opposite of the first direction; applying the first control
signal to the first proportional pilot valve to move the spool of
the piloted spool valve in the first direction; applying the second
control signal to the second proportional pilot valve to move the
spool of the piloted spool valve in the second direction at
substantially the same time as the applying of the first control
signal; moving the spool of the piloted spool valve by a combined
amount and in a combined direction determined by both the first
control signal and the second control signal.
2. The method of claim 1 wherein the generating the first control
signal further comprises generating the first control signal in
response to an operator control signal, wherein the operator
control signal is configured to adjust an actuator.
3. The method of claim 1 wherein the generating the first control
signal further comprises generating the first control signal in
response to a drift control signal, wherein the drift control
signal is configured to adjust a position of a work implement which
encounters drift forces.
4. The method of claim 1 wherein the generating the second control
signal further comprises generating the second control signal to
have a value of less than the first control signal.
5. The method of claim 1 wherein the generating the second control
signal further comprises generating the second control signal to
have a value equal to a predetermined value, wherein the
predetermined value is a threshold value.
6. The method of claim 1 wherein the generating the second control
signal further comprises generating the second control signal to
have a value of one of: a) a value less than the first control
signal; and b) the value of the first control signal.
7. The method of claim 1 further comprising generating a constant
current signal and modifying one of the generated first control
signal and the generated second control signal with the constant
current signal.
8. A control method for a work machine including a control system,
an actuator for moving a work implement, a spool valve, and an
operator control, the control method comprising: generating a first
control signal responsive to the operator control, the first
control signal for moving a spool of the spool valve in a first
direction; generating a second control signal as a function of the
generated first control signal, the second control signal for
moving the spool of the spool valve in a second direction, the
second direction being opposite of the first direction; adjusting a
position of the spool of the spool valve in response to concurrent
transmission of the first control signal and the second control
signal; and moving the work implement responsively to the adjusting
of the spool.
9. The control method of claim 8 wherein the adjusting the position
of the spool valve includes adjusting the position of the spool
with a first proportional control valve receiving the generated
first control signal and a second proportional control valve
receiving the generated second control signal.
10. The control method of claim 8 wherein the generated first
control signal and the generated second control signal are
generated in response to an operator control signal provided by the
operator control.
11. The control method of claim 8 wherein the generated first
control signal and the generated second control signal are
generated in response to a drift control signal, wherein the drift
control signal is configured to adjust the position of the work
implement which encounters drift forces.
12. The control method of claim 8 wherein the generating the second
control signal further comprises generating the second control
signal to have a value of less than the first control signal.
13. The control method of claim 8 wherein the generating the second
control signal further comprises generating the second control
signal to have a value equal to a predetermined value, wherein the
predetermined value is a threshold value.
14. The control method of claim 8 wherein the generating the second
control signal further comprises generating the second control
signal to have a value of one of: a) a value less than the first
control signal; and b) the value of the first control signal.
15. The control method of claim 8 further comprising generating a
constant current signal and modifying one of the generated first
control signal and the generated second control signal with the
constant current signal.
16. A work machine configured to cut timber with a rotating saw
blade, the work machine comprising: a felling head; a hydraulic
motor including a motor shaft configured to adjust the position of
the felling head; a spool valve operatively connected to the
hydraulic motor, the spool valve having a spool and being
configured to move the motor shaft; a first and a second
proportional control valve operatively connected to the spool
valve; an operator controller operatively connected to the
hydraulic motor, the operator controller being configured to move
the hydraulic motor; and a machine controller coupled to the
operator controller and the spool valve, the machine controller
configured to execute stored program instructions to: generate a
first control signal responsive to an operator control signal
provided by the operator controller, the first control signal to
move the spool of the spool valve in a first direction; generate a
second control signal as a function of the generated first control
signal, the second control signal to move the spool of the spool
valve in a second direction which is opposite of the first
direction; adjust a position of the spool of the spool valve in
response to a concurrent reception of the first control signal and
the second control signal by the first proportional control valve
and the second proportional control valve to move the felling head
through operation of the hydraulic motor.
17. The work machine of claim 16 wherein the program instructions
to generate a first control signal and to generate a second control
signal as a function of the generated first control signal include:
generate the second control signal to have a value of less than the
first control signal.
18. The work machine of claim 16 wherein the program instructions
to generate a first control signal and to generate a second control
signal as a function of the generated first control signal include:
generate the second control signal to have a value equal to a
predetermined value.
19. The work machine of claim 16 wherein the program instructions
to generate a first control signal and to generate a second control
signal as a function of the generated first control signal include:
generate the second control signal to have a value of one of: a) a
value less than the first control signal; and b) the value of the
first control signal.
20. The work machine of claim 16, wherein the machine controller is
further configured to execute stored program instructions to:
modify one of the generated first control signal and the generated
second control signal with a constant current signal.
Description
FIELD OF THE DISCLOSURE
[0001] The present disclosure generally relates to a proportional
valve, and more particularly to controlling a proportional valve of
a work vehicle.
BACKGROUND
[0002] Work vehicle movement may be controlled by hydraulic
proportional valves which direct pressurized hydraulic fluid to
various hydraulic actuators on the work vehicle. Electrohydraulic
valves may be utilized for these proportional valves.
[0003] As an example of such a work vehicle, operators may use
feller bunchers to harvest trees and other wood vegetation. A
typical tree feller buncher first cuts the tree and then places the
tree in bunches on the ground for further processing with other
machines, such as skidders or forwarders. Some tree feller bunchers
include a felling head with a cutting device for cutting the trees
and an accumulation pocket for receiving and holding one or more
felled trees until the felled trees are placed in bunches on the
ground.
SUMMARY
[0004] According to one embodiment of the present disclosure, there
is provided method of controlling a piloted spool valve with a
first proportional pilot valve and a second proportional pilot
valve, wherein the piloted spool valve drives a shaft of a motor
configured to position a work implement of a work machine. The
method includes generating a first control signal responsive to a
motor shaft position signal and generating a second control signal
as a function of the generated first control signal. The method
further includes applying the first control signal to the first
proportional pilot valve, applying the second control signal to the
second proportional pilot valve at substantially the same time as
the applying of the first control signal, and moving the spool of
the piloted spool valve in a direction determined by both the first
control signal and the second control signal.
[0005] According to another embodiment of the present disclosure,
there is provided a drift control method for a work machine
including a control system, a cutting tool, a motor having a motor
shaft for moving a work implement, a spool valve, and an operator
control. The drift control method includes generating a first
control signal responsive to one of a drift control signal and an
operator control signal, generating a second control signal as a
function of the generated first control signal, adjusting a
position of the spool of the piloted spool valve in response to
concurrent transmission of the first control signal and the second
control signal, and moving the work implement responsively to the
adjusting of the spool.
[0006] In another embodiment, there is provided a work machine
configured to cut timber with a rotating saw blade. The work
machine includes a felling head, a hydraulic motor including a
motor shaft configured to adjust the position of the felling head,
and a spool valve operatively connected to the hydraulic motor
wherein the spool valve is configured to move the motor shaft. The
work machine further includes a first and a second proportional
control valve operatively connected to the spool valve, an operator
controller operatively connected to the hydraulic motor wherein the
operator controller is configured to move the hydraulic motor, and
a machine controller coupled to the operator controller and the
spool valve wherein the machine controller is configured to execute
stored program instructions. The stored program instructions are
configured to generate: a) a first control signal responsive to an
operator control signal provided by the operator controller; b)
generate a second control signal as a function of the generated
first control signal; and c) adjust a position of the spool of the
spool valve in response to a concurrent reception of the first
control signal and the second control signal by the first
proportional control valve and the second proportional control
valve to move the felling head through operation of the hydraulic
motor.
[0007] Additional features and advantages of the present disclosure
will become apparent to those skilled in the art upon consideration
of the following detailed description of the illustrative
embodiment exemplifying the best mode of carrying out the
disclosure as presently perceived.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The above-mentioned aspects of the present disclosure and
the manner of obtaining them will become more apparent and the
disclosure itself will be better understood by reference to the
following description of the embodiments of the disclosure, taken
in conjunction with the accompanying drawings, wherein:
[0009] FIG. 1 is a side elevational view of a work machine
including a felling head;
[0010] FIG. 2 is a schematic of a control system for controlling
the operation of a hydraulic motor of a work machine;
[0011] FIG. 3 is a schematic of a first and second proportional
pilot solenoid valve coupled to an electro-hydraulic spool
valve;
[0012] FIG. 4 is a flow diagram of a control system configured to
adjust the position of a spool valve; and
[0013] FIG. 5 is a schematic depiction of a logic arrangement
configured to control a proportional pilot solenoid valve.
DETAILED DESCRIPTION
[0014] For the purposes of promoting an understanding of the
principles of the novel disclosure, reference will now be made to
the embodiments described herein and illustrated in the drawings
with specific language used to describe the same. It will
nevertheless be understood that no limitation of the scope of the
novel disclosure is intended. Such alterations and further
modifications of the illustrated apparatus, assemblies, devices and
methods, and such further applications of the principles of the
novel disclosure as illustrated herein, are contemplated as would
normally occur to one skilled in the art to which the novel
disclosure relates.
[0015] In FIG. 1 an example of a work machine, such as a track
feller bencher 100 is shown. The present disclosure is not limited,
however, to track feller bundlers and other work machines used in
the construction, forestry, and agricultural industries having
wheels or skids are also included. As such, while the figures and
forthcoming description may relate to a track feller bencher, it is
to be understood that the scope of the present disclosure extends
beyond a track feller buncher, and where applicable, the term
"machine," "work machine," or "work vehicle" will be used instead.
The term "machine," "work machine," or "work vehicle" is intended
to be broader and encompass other vehicles besides a feller buncher
for purposes of this disclosure.
[0016] The machine 100 includes an upper frame assembly 102 which
is supported by an undercarriage assembly 104. The upper frame
assembly 102 can include a cab 106 in which an operator utilizes a
plurality of controls (e.g., joysticks, pedals, buttons, screens,
etc.) for controlling the machine 100 during operation thereof. The
upper frame assembly 102 also includes an engine compartment that
houses an engine, such as a diesel engine which provides the motive
power for operating the components associated with the machine 100.
Both the cab 106 and the engine compartment can be supported by
various frame members that form the upper frame assembly 102.
[0017] The undercarriage assembly 104, in one embodiment, includes
tracks 108 (e.g., one on a leftside of the machine and another on a
rightside thereof) that engage and move along the ground during
operation. The tracks 108 are driven by a drive sprocket (not
shown) and a front idler wheel (not shown) about which a track
chain (not shown) is entrained. A hydraulic motor operably drives
the drive sprocket (which may form part of a high reduction
gearset) so as to drive the track chain (not shown) thereby
providing motive power for moving the machine 100.
[0018] The upper frame assembly 102 can be mechanically coupled to
the undercarriage assembly 104 by a tilt mechanism and turntable
assembly 110. The tilt mechanism and turntable assembly 110
operably controls the machine 100 to be rotated and tilted about
one or more axes. A swing assembly 112, for example, includes one
or more swing motors for driving rotation of the upper frame
assembly 102 relative to the undercarriage assembly 104. Operation
of the swing assembly 112 rotates a platform 120 of the upper frame
assembly 102 relative to the undercarriage 104.
[0019] The work machine 100 includes a boom assembly 114. The boom
assembly 114 includes a first boom section 122 pivotably coupled to
a second boom section 124. As shown in FIG. 1, one end of the first
boom section 122 is pivotably coupled to the upper frame assembly
102 via a first pivot pin 126. An opposite end of the first boom
section 122 is pivotably coupled at a second pivot pin 128 to a
first end of the second boom section 124. The second boom section
124 includes a second end coupled to a wrist assembly 116. The
wrist assembly 116 includes one or more hydraulic motors for
powering a work element. As shown in FIG. 1, the work implement
coupled to the wrist assembly 116 is a felling head 118 for cutting
and bunching trees or other woody vegetation.
[0020] The work machine 100 may also include a plurality of
actuators for controlling the boom assembly 114 and felling head
118. In the example of FIG. 1, the machine 100 includes a first
hydraulic actuator 130, a second hydraulic actuator 132, and a
third hydraulic actuator 134.
[0021] Felling head 118 includes a support frame 136 supported by
the wrist assembly 116. Movement of the wrist assembly 116 is
adjustably controllable by the operator located in the cab 106 in
different directions including rotation about a longitudinal axis
137. This rotational movement is controllable both by operator
control as well as by automatic control provided by a machine
controller.
[0022] Felling head 118 includes a cutting tool assembly 138 and an
accumulation pocket 140 into which felled trees are directed for
short-term storage while additional trees are felled. The cutting
tool assembly 138 is supported by the support frame 136. A housing
142 of the support frame 136 surrounds the cutting tool assembly
138. The tree cutting tool assembly 138 is used to cut a tree trunk
or vegetation from its roots. According to the exemplary embodiment
of the present disclosure, felling head 118 includes the housing
142 and a circular saw blade (not shown) that rotates about an axis
of rotation. The portion of the blade is covered by saw housing 142
and another portion of the blade is exposed to cut the trees or
vegetation.
[0023] Frame 136 also pivotably supports a gathering arm 146 and an
accumulation arm 144 that gather and hold felled trees in
accumulation pocket 140. As shown in FIG. 1, gathering arm 146 is
designed to guide cut trees into the accumulating pocket, while
accumulation arm 144 is designed to hold the accumulated trees in
the pocket. Additional details of an alternative gathering arm are
provided in U.S. Pat. No. 5,697,412, the entire disclosure of which
is expressly incorporated by reference herein.
[0024] FIG. 2 illustrates a control system 200 for controlling the
operation of a hydraulic motor 201, which in one embodiment is used
to position the felling head 118 about the axis 137. The control
system 200, is not however, limited to the control of felling head
118 about the axis 137, but in different embodiments is used to
control hydraulic motors used in other applications including
movement of the felling head in other directions, as well as
movement of the cab 106 about a rotational axis thereof. The system
200 includes a controller 202 configured to control the
functionality of the machine 100. In different embodiments, the
controller 202 includes a memory unit 204 and a processor 206. The
memory unit 204 is configured to store one or more control
functions, which is a set of instructions executed by the processor
206 for controlling movement of the felling head 118. In other
embodiments, other actuators, including hydraulic cylinders, are
controlled by the control system 200.
[0025] The controller 202, in one embodiment, is coupled to an
operator control 208 such as a joystick, lever, switch, trigger
switch, pedal, and the like. The operator control 208 is used by
the machine operator to control, in one embodiment, a wrist
function for adjusting the position of the feller head 118 about
the axis 137. For example, if the operator control 208 is a trigger
switch for controlling the motor 201 to adjust the position of the
head 118, the operator controls rotational movement of the felling
head 208 relative to the boom assembly 114 of the machine 100.
[0026] The operator control 208 is in electrical communication with
an input 212 of the controller 202. An output 214 and an output 215
of the controller 202 are respectively coupled to an input 217 of a
first proportional control valve 228 and to an input 219 of a
second proportional control valve 230. The control valve 216 is
controlled electrically by the controller 202 via the first and
second proportional control valves 228 and 230. In one embodiment,
a first spring 232 is disposed adjacent the first solenoid 228 at
the control valve 216, and a second spring 234 is disposed adjacent
the second solenoid 230 at the control valve 216. In this
embodiment, the first and second springs are configured to center
the valve control spool. The solenoid controlled pilot pressure
shifts the spool from a center position against these springs. The
first and second solenoids 228 and 230 receive electrical current
from the controller 202 to move the control valve 216.
[0027] In one embodiment, the control valve 216 is an
electro-hydraulic control valve that is controlled electrically to
provide hydraulic fluid flow to the hydraulic motor 201. The
control valve 216 is fluidly coupled to a hydraulic pump 220 that
provides hydraulic pressure, P, to drive the motor 218, and to a
reservoir, or tank T, that holds hydraulic fluid. The control valve
216 is fluidly coupled to the motor 218 via a first port 224 and a
second port 226. In different embodiments, hydraulic fluid flows to
either the first or second port to induce rotational movement of a
motor shaft (not shown).
[0028] As is also shown in FIG. 2, a motor shaft sensor 210 is
shown. The sensor 210 is in electrical communication with an input
211 of the controller 202 to provide information about the motor
shaft. This sensor 210 may be any type of speed sensor capable of
detecting rotational speed, angular distance traveled, or position.
The sensor 210, in different embodiments, is coupled directly to
the shaft as a contact-type speed sensor, or it may be a
contact-less sensor or Hall Effect sensor. In other embodiments,
the sensor 210 is a Vehicle Stability Sensor (VSS) such as a John
Deere F673013 Inertial Measurement Unit (IMU) that is designed to
provide motion sensing using up to six (6) degrees of freedom. The
VSS detects or measures the position of the felling head 118
relative to gravity.
[0029] A speed output via a speed sensor pickup may be used to
communicate information such as speed and direction of the felling
head 118 about the motor shaft to the controller 202. The motor
shaft speed sensor 210 communicates rotation and/or position of the
motor shaft as the felling head 118 moves with respect to the boom
assembly 114.
[0030] FIG. 3 illustrates operating characteristics of the control
valve 216, the first proportional valve 228, and the second
proportional valve 230, which are optimized by the present
disclosure to controllably adjust the position of the spool. In
known systems, the actuation of a control valve, such as control
valve 216 is made by activating only one of the valves 228 or 230,
but not the other, with one of an appropriate control current IA,
an input current A applied to an input 217 or IB, an input current
B applied to an input 219, each of which respectively receives the
control current from the controller outputs 214 and 215. Upon
actuation of the valve 228 by the current IA, the valve 228
responds by providing a pilot pressure signal (PpA) to the control
valve 216 through an orifice 240, which is sized to prevent the
control valve 216 from operating too quickly. The pilot pressure
signal is a fluid having a pressure determined by the value of the
current IA. The pilot pressure signal is provided to the control
valve 216 at an input 242 thereof to move a spool of the control
valve in the positive X direction as illustrated, at which point an
output fluid flow of fluid from a port 244 is delivered to the
motor 201 at the input 224 of FIG. 2.
[0031] While the control valve 216 includes springs having a spring
stiffness to dampen movement of the spool in either direction, the
movement of the spool is not precisely controlled, resulting in an
oscillation of the spool for a period of time before settling to a
final position.
[0032] To move the shaft of the motor 201 in the opposite
direction, a pilot pressure signal PpB, is delivered through an
orifice 246 in response to a current IB provided by the controller
202 at the output 215. The pilot pressure signal, PpB, is provided
to the control valve 216 at an input 248 thereof to move the spool
of the control valve in the negative X direction as illustrated. At
this time, an output fluid flow of fluid from a port 250 is
delivered to the motor 201 at the input 226 to move the motor shaft
in the opposite direction. Movement of the spool in the negative X
direction, however, again is not precisely controlled, such that
the spool tends to oscillate for a period of time before settling
to its final position.
[0033] During forestry operations, the swing and boom mechanism
experience highly dynamic and variable loads, which can generate
unstable responses from the hydraulic system. Because the loads can
be unstable due to weight shifting of the load and irregularities
of the terrain upon which the machine moves, it would be desirable
to provide a faster and more stable control of the spool position
and spool output to improve the harvesting of timber.
[0034] The present disclosure provides a faster and more stable
control of the spool position and spool output by activating both
of the valves 228 and 230 concurrently, or at the same time. A
command current, either IcA, for valve 228 (valve A), or IcB, for
valve 230 (valve B) is provided to one of the valves 228 or 230. At
the same time, a reaction current Ica or Icb is provide to the
other valve which provides a dampening force to move the spool in a
direction opposite to the direction made in response to the command
currents. As used herein, the reaction signals are identified as
Ica or Icb, where the lower case letter "a" or "b" signifies a
signal provided to respective solenoids 228 (the A solenoid) and
230 (the B solenoid), which are not command signals but which are
instead reaction signals.
[0035] Each of the currents IcA and IcB is determined by the
controller 202 which is configured to execute program instructions
stored in a memory, such as the memory 204. The processor 206 is
configured to execute the stored program instructions to determine
the values of the currents IcA and IcB in response to the
operator's commands provided by the user interface. As used herein,
the command current IcA is provided to the first solenoid 228 for
movement of the spool in the positive X direction. The command
current IcB is provided to the second solenoid 230 for movement of
the spool in the negative X direction.
[0036] When a command signal IcA or IcB is provided to the
respective solenoids 228 and 230, the reaction signal, Ica or Icb,
is generated and is based on the command current which is
transmitted. Each of the command signals IcA and IcB is used to
generate the reaction signal which provides a response or reaction
to the command signals. In one example, if solenoid 228 receives a
command signal IcA to move the spool in the +X direction, a
reaction signal, Icb, which is determined as a function of the
command current IcA, is applied to the other solenoid 230. The
reaction signal is, in one embodiment, a signal which is less than
or equal to the command signal. By controlling the dynamics of the
spool position, which is in response to the operator command and
load variations, the application of a command current and reaction
current at the same time to the solenoids 228 and 230 provides a
smoother, more consistent, and more accurate operation.
[0037] By engaging software program instructions over each of the
proportional pilot solenoids 228 and 230, the program instructions
are independent of the system temperatures and/or independent of
the system loads as required.
[0038] Simultaneous control of the valves 228 and 230 provides a
more consistent and stable control over the spool position
dynamics, and as a consequence, a smoother and more controllable
machine 100. By activating each of the solenoids 228 and 230 at
substantially the same time with a main command current (say IcB to
command solenoid 230) with a reaction current (say Ica to command
solenoid 228), the solenoids 228 and 230 provide for the adjustment
of the motor 201 that is independent of temperature, fluid
viscosity, and load.
[0039] FIG. 4 illustrates one embodiment of a flow diagram of a
control system 300. The control system 300 is responsive to one or
more control signals from an automated system output of the machine
100 which provides a control signal from proportional integral
derivative (PID) control signal at an input 302. In one embodiment,
the control signal from the PID controller controls the position of
the motor 201 to compensate for drift that occurs resulting from
fluid leakage of a machine, undesirable rotation of the wrist motor
which can result from load imbalances, and fluid leakage across the
control valve between a hydraulic pump and hydraulic motor. The
control signal from the PID controller is provided at an input 304
of the control system.
[0040] As described herein, various functions provided by the
control system 300 are embodied in the controller 202 which, in
different embodiments, includes hardware devices, software
applications, or a combination of both hardware devices and
software applications. The controller 202 is configured to execute
or otherwise rely upon computer software applications, components,
programs, objects, modules, or data structures, etc. Software
routines resident in the included memory 204, other external memory
(not shown), or provided as firmware, are executed in response to
the various signals received and generated as described herein. The
executed software includes one or more specific applications,
components, programs, objects, modules or sequences of instructions
typically referred to as "program code". The program code includes
one or more instructions located in memory, other storage devices
or elsewhere, such as the "cloud" (a network of remote servers
hosted on the Internet), which execute the request provided by
control signal provided by the PID controller 302 and other
described operator inputs.
[0041] An optional operator control is provided, in one or more
embodiments, in the cab 106 to enable the operator to manually turn
on or turn off drift control provided by the PID controller at 302.
The desired state of the drift control is provided at an input 306.
Under some conditions, the operator does not want to correct for
drift, and therefore adjusts a switch or other button to manually
disable drift control. In some instances, a single button may be
used to disable all drift control functions, and in other instances
there may be a button or control for enabling or disabling each
drift control function.
[0042] As further illustrated in FIG. 4, an operator controller
308, such as a trigger controller, is operatively connected to an
input 310 of a process operator 312 which is operatively connected
to a proportional pilot valve 314. The operator controller 308 is
also operatively connected to a process operator 316, which is
operatively connected to a proportional pilot valve 318. The
controller 308, in one embodiment, provides an output of zero (0)
if no movement of the motor 201 is requested by the operator. If
however, the operator requests a clockwise (CW) movement of the
feller head 118, a value of one (1) is transmitted to the process
operator 312. If the operator requests a counterclockwise (CCW)
movement of the feller head 118, a value of 1 is transmitted to the
process operator 316. Each of the valves 314 and 318 is operatively
connected to a spool valve 319, which includes a moveable
spool.
[0043] The system 300 receives the PID control signal 302 at the
input 304 which is received by a process operator 320 at an input
322. In one embodiment, the PID control signal 302 provides
directional control of the feller head 118 about the axis 137 of
FIG. 1. The control signal 302 is a function of the automated
system output, which is provided to maintain the positon of the
feller head 118 when experiencing external forces, such as movement
of the machine 100, movement of the boom assembly 114, and movement
of the feller head 118. The process operator 320 includes a second
input 324 which is coupled to an output 326 of a process operator
328.
[0044] A decision operator 330 receives a signal from the process
operator 320, which provides the PID control signal 302 to an input
332 of the decision operator 330. The process operator also
receives a signal from the output 326 of the process operator 328.
The signal received at the input 332 is compared to a predetermined
value, the result of which is used to move the shaft of the motor
in one of two directions. In the illustrated embodiment, a value of
zero (0) is used in the comparison to determine the rotational
direction of the motor shaft. If the signal is less than zero, the
signal is sent to a decision operator 334 at an input 336. If the
signal is greater than zero, the signal is sent to a decision
operator 338 at an input 340. In either case, the resulting output
of the process operator 330 is a signal having a value which is
used to determine an actual amount of rotational movement to be
experienced by the motor shaft as determined by the PID
controller.
[0045] Each of the decision operators 334 and 338 receives the
drift control input 306. If the drift control input 306 is off, for
instance a zero, neither of the decision operators 334 and 338
provides an output signal for controlling the proportional control
valves 314 and 318. Instead, the process operator 328 receives a
signal from either of the decision operators 334 and 338 indicating
that the drift control is turned off. If, however, the drift
control signal is on, then the value of the PID control signal is
respectively transmitted from the decision operator 334 or 338,
which has been enabled by the drift control signal, to a solenoid A
logic arrangement 342 or to a solenoid B logic arrangement 344. In
this embodiment, solenoid A logic is used to control the valve 314
and solenoid B logic is used to control the valve 318. One
embodiment of the solenoid A logic arrangement is further
illustrated in FIG. 5.
[0046] As seen in FIG. 5, the solenoid A logic arrangement 342
receives as a primary input the output of the decision operator
334, which corresponds to the command signal IcA. The same signal,
IcA, is also transmitted to the solenoid B logic arrangement, where
it is used to determine the reaction signal Icb, which is input to
the valve 318. Likewise, the solenoid B logic arrangement receives
as a primary input the output of the decision operator 338, which
corresponds to the command signal IcB. The same signal, IcB, is
also transmitted to the solenoid A logic arrangement where it is
used to determine the reaction signal Ica, which is input to the
valve 314. Each of the logic arrangements 342 and 344 also receives
a minimum current signal, or value, from a minimum current device
346. The minimum current value is set to a predetermined value to
maintain the solenoids 314 and 318 at a setpoint location to reduce
the effects of device drift which can affect the valves 314 and
318.
[0047] FIG. 5 illustrates one embodiment of the solenoid A logic
arrangement 342 used to control the valve 314, when valve 318 is
being commanded to move in the negative X direction by IcB. The
solenoid B logic arrangement 344, in one embodiment, is
substantially the same as the solenoid A logic arrangement and
consequently, the discussion of the operational characteristics of
solenoid A logic arrangement 342 is equally applicable to the
operational characteristics of solenoid B logic arrangement
344.
[0048] A logic condition 350 is set by the controller 202 to
indicate whether or not operator controller 308 has been activated
for movement of the spool in either the +X or -X direction of FIG.
3. In the event that the operator controller 308 is not activated,
the value of the logic condition is zero (0) and the value of zero
is compared to a constant, which in this example is a one (1).
Since the logic condition 350 is zero (not equal to one), then no
trigger is activated and the output of a comparison block 352 is a
zero, indicating that no operator controller, a trigger in this
ease, has been activated. If however, the logic condition is set to
a one (1), a value of one is transmitted by the comparison block
352 to a product block 354 which includes a first input 353. The
product block 354 also includes a second input 355. If the value at
the input 353 is zero, there is no output signal transmitted by the
product block 354 at an output 357. If however, the value at the
input is a one, then a signal appearing at the input 355 passes
through the product block 354 on the output 357.
[0049] In the event that the trigger 308 is activated to move the
spool in the -X direction, there is no output of the decision
operator 334, and consequently, there is no command current IcA for
the solenoid 314. In this instance, the CCW signal is a one (1) and
a command current IcB is transmitted to the solenoid B logic
circuit 344.
[0050] In this example, the trigger 308 is activated to move the
spool in the -X direction and consequently, there is no command
current IcA for the solenoid 314. A command current IcB is,
therefore, transmitted to the solenoid B logic circuit 344.
[0051] The value of the IcA request signal 356 is provided to a
first input 361 of a summation block 362. In this example, the IcA
request 356 is zero, since the B solenoid, 318 is being commanded
to move the spool in the -X direction.
[0052] The IcB signal is transmitted to the solenoid A logic 342
over a signal line 358 of FIG. 4. This IcB signal is received at an
input 359 of the solenoid A logic of FIG. 5. Since the spool is
being commanded to move in the -X direction in this example, the
IcB signal has a value of something other than zero. (A similar
signal line 360 of FIG. 4 transmits the IcA command signal, when
the valve 314 is being commanded to move the spool in the +X
direction.)
[0053] Even though the valve 318 is being commanded by the IcB
signal to provide most of the spool movement in the -X direction,
the same IcB signal is used by the solenoid A logic 342 to
determine the value of the Ica reaction signal to be provided to
the valve 314.
[0054] The Ica signal is determined as a function of a minimum
current provided by the current block 346 of FIG. 4 and received at
an input 364 of FIG. 5. In one embodiment, the current provided is
three-tenths (0.3) of an amp. This value, however, is only
exemplary and other values are possible in this and other systems.
The current provided at the input 364 is provided to a second input
366 of the summation block 362.
[0055] The IcB command current provided at the input 359 is
modified at a signal level adjuster 368. In the illustrated
embodiment, the signal level adjuster 368 provides a threshold
function. The threshold block 368 receives as an input the IcB
signal and provides an output signal, the Ica signal, at the output
370. The Ica signal, in this example, is equal to the value of the
IcB signal or is less than the IcB signal, depending on the value
of the IcB signal. If the actual value of the IcB signal exceeds a
predetermined value (a threshold level), the value of the Ica
signal is set to the predetermined value.
[0056] In one example, if the predetermined value is set to 200
milliamps, the value of the Ica signal is set to 200 milliamps,
when the IcB value exceeds 200 milliamps. If the value of the IcB
signal is less than 200 milliamps, however, then the Ica value is
set equal to the value of IcB received at the input 368 of the
threshold block. The Ica signal is transmitted to the summation
block 362 at the third input 372. In other embodiments, the signal
level adjuster 368 determines the value of the IcB signal at the
output 370 as a function of other than a threshold level
determination. For instance, the Ica signal could be set to
one-half the value of the IcB signal.
[0057] The summation block 362 receives three input signals. The
signals received at the first input 361 and second input 366 are
added together. The signal received at the third input is
subtracted from the result of the summation of the first and second
inputs 361 and 366. These inputs are designated with the
appropriate labeling of a plus sign (+) to indicate addition or a
minus sign (-) to indicate subtraction. The resulting signal is
provided at an output 374 which is coupled to the input 355 of the
product block 354. When the value at the input 353 is a one (1),
the value at the input 355 passes through the product block 354 to
the output 357.
[0058] The output 357 is coupled to an input 380 of the process
operator 312 of FIG. 4. An output 382 of the process operator 312
is coupled to the valve 314 of FIG. 4. In this example, the
greatest amount of movement of the valve 319 is in the -X
direction. The distance of movement in the -X direction is,
however, reduced by the value of the Ica signal applied to valve
314.
[0059] The solenoid B logic 344 is similarly configured as the
solenoid A logic 342 as described herein.
[0060] In another embodiment, the command signal is configured to
drive the respective proportional control valve to a saturation
level to move the spool in a first direction and the reaction
signal is appropriately sized to adjust movement of the spool in
the opposite direction. In other embodiments the saturated command
signal is provided when the operator generated command signal
exceeds a predetermined value.
[0061] While exemplary embodiments incorporating the principles of
the present disclosure have been disclosed herein, the present
disclosure is not limited to the disclosed embodiments. Instead,
this application is intended to cover any variations, uses, or
adaptations of the disclosure using its general principles. For
instance in different embodiments, the functions described herein
are embodied as hardware devices, software applications, or a
combination of both hardware devices and software applications.
Therefore, this application is intended to cover such departures
from the present disclosure as come within known or customary
practice in the art to which this disclosure pertains.
* * * * *