Electro-mechanical isotonic or isokinetic exercising system

Abstract

A feed-back controlled system utilizing electronic and electro-mechanical devices as controlled exercising loads for use in isotonic or isokinetic exercising therapy, the equipment affording a wide variety of operating modes.

Description

BACKGROUND OF THE INVENTION

In recent years, the use of special exercises and associated equipment has become relatively highly developed and has been scientifically applied as physical therapy for the restoration of injured limbs as well as for routine use by athletes and others in building muscles or increasing physical strength and stamina.

Numerous papers and articles have been written advocating special types of exercises for specific purposes. Thus, for example, isotonic (constant force) exercises will be recommended on one case while isokinetic (resistance directly proportional to the force exerted) exercises are preferred in another.

It is helpful to therapists, trainers, etc. who wish to establish systematic exercise programs for specific purposes if the exercises they prescribe can be scientifically controlled and monitored, and in response to this need, devices of this type are gradually being developed and introduced.

Another desirable characteristic of such equipment is portability, in some cases, especially in the case of the athlete who must continue his exercise program while having to be constantly on the road travelling from game to game.

SUMMARY OF THE INVENTION

In accordance with the invention claimed, an improved electro-mechanical device is provided for supplying electronically controlled exercising loads in a number of special modes including both isotonic and isokinetic types.

It is, therefore, one object of this invention to provide such a device which is operative in a "normal" mode wherein resistance of a constant amount is supplied in both the lifting or "positive" stroke as well as in the lowering or "negative" stroke. This mode is similar to using weights.

Another object of this invention is to provide such a device which is also operative in a "positive only" mode wherein resistance is provided in the lifting stroke, but no force is applied in the lowering stroke.

A further object of this invention is to provide such a device which is operative also in the "negative only" mode wherein force is supplied in the lowering stroke, but no resistance is applied in the lifting stroke.

A still further object of this invention is to provide a device which is operable in an "automatic" or double isokinetic mode wherein resistance is supplied in the lifting stroke just sufficiently less than the force applied by the subject to permit the lifting stroke to be completed. In the lowering stroke, the machine supplies just sufficiently more force than the resistance applied by the subject to allow the lowering stroke to be completed.

A still further object of this invention is to provide such a device which is operative also in an "automatic, negative only" mode wherein such controlled resistance is provided only in the lowering stroke with no resistance supplied in the lifting stroke.

A still further object of this invention is to provide such a device which is applicable in cases where the subject is intended to react passively while his limbs are exercised through a desired pattern of motions at a given speed as might be appropriate, for example, in the treatment of a stroke patient.

A still further object of this invention is to provide such a device which is operative also in a constant speed mode independent of the reactionary forces posed by the subject.

A still further object of this invention is to provide such a device in a compact and sometimes portable form.

Further objects and advantages of the invention will become apparent as the following description proceeds and the features of novelty which characterize this invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

BRIEF DESCRIPTION OF THE DRAWING

The present invention may be more readily described by reference to the accompanying drawing, in which:

FIG. 1 is a block diagram representing the exercise device and associated feed-back control system;

FIG. 2 is a functional diagram of an embodiment of the invention in a very simple form; and

FIG. 3 is a modification of a part of the circuitry shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring more particularly to the drawing by characters of reference, FIG. 1 discloses in block diagram form a feed-back controlled electronic or electro-mechanical exercise device 10 comprising a motor 11, a tachometer 12, a position sensor 13, and a clutch 14 coupled together by suitable means such as, for example, a gear-train 15, a function generator 16, a motor-control amplifier 17, a clutch control amplifier 18, a motor reversing switch 19, and a motor mode control selection means such as switch 20.

In operation, motor 11, which has drive terminals 22 and 23 is energized by a positive drive current entering at either terminal 22 or terminal 23 as determined by the position of reversing switch 19, the positive drive current being generated by amplifier 17 and delivered to switch 19 via line 24, and passing through switch 19 into terminal 22 or 23, out again through terminal 23 or 22, through switch 19 and a current-sensing resistor 25 to ground terminal 26.

For a constant-speed mode of operation, amplifier 17 receives a signal at its control input 27 from output terminal 28 of tachometer 12 and at reference input 29 from reference potentiometer 31 which also may be any form of voltage divider. In this mode of operation, the drive current supplied by amplifier 17 increases until motor speed as indicated by the output signal of tachometer 12 reaches a value corresponding to the setting of potentiometer 31. At this value of motor speed, the electrical signal from tachometer 12 delivered to terminal 27 will be just equal to the voltage delivered to terminal 29 from potentiometer 31. The closed loop comprising motor 11, tachometer 12 and amplifier 17 will cause the speed of motor 11 to be held at this constant value independent of the load or torque applied to motor 11.

The operating mode of motor 11 may be changed from the constant-speed mode just described to a constant-torque mode by operating switch 20 to select position B instead of the position in which it is shown. When switch 20 is in position B, control terminal 27 of amplifier 17 receives a signal from current-sensing resistor 25. Resistor 25 carries drive current from motor 11 and a voltage signal is developed across resistor 25 which is proportional to motor current and hence also to motor torque. In this mode, a constant current will be supplied motor 11, the value being determined by the setting of potentiometer 31 and motor 11 will therefore operate at constant torque independent of the load applied.

A variety of exercise equipment, such as levers, ropes, draw-bars, etc. may be driven by motor 11 with coupling through gear train 15 and clutch 14 to load drive shaft 32.

As a safety measure, it is desirable to limit the maximum torque delivered to shaft 32. This is accomplished through the use of amplifier 18. The control terminal 33 of amplifier 18 senses motor torque by virtue of its connection across resistor 25. Reference terminal 34 of amplifier 18 is connected to a voltage control means, such as a potentiometer 35 so that an adjustable reference voltage may be supplied. When motor torque exceeds a value which causes the control voltage at terminal 33 to exceed the set reference voltage seen at terminal 34 a positive signal at output terminal 36 of amplifier 18 is delivered via line 37 to clutch 14 which causes clutch 14 to disengage from shaft 32, thereby releasing the load from coupling with motor 11.

Function generator 16 receives electrical signals from tachometer 12 and from position sensor 13 via lines 38 and 39, respectively, and may be programmed to deliver control signals via one or more of its output signal lines 41, 42 and 43 to control the position of reversing switch 19, the level of voltage supplied to reference potentiometer 31 or to control the operation of clutch 14.

Thus, for example, the signal from position sensor 13 may be employed in such a manner that at a given position, reversing switch 19 is operated to reverse the direction of motor 11. In another mode, motor speed may be altered as a function of position. In yet another mode, the clutch may be disengaged for a return stroke or the reversing switch may be operated in response to the attainment of a given speed, etc. The great variety of such functions possible through the use of such a function generator incorporated as an element of device 10 is an important and novel feature of this invention.

While this invention is intended to embody the broad range of possible control functions permitted by the system shown in FIG. 1, its principles are operative also in the case of the simplified control system 50 of FIG. 2 which comprises an integrated hydraulic motor, pump, and fluid reservoir unit 51 connected by fluid drive lines 52 and 53 and valves 54 and 55 to a hydraulic cylinder 56. Inside cylinder 56, a piston 57 is driven from right to left as fluid is pumped into cylinder 56 via line 53 and it is driven from left to right as fluid is pumped out of cylinder 56 via line 52. Valves 54 and 55 are one-way valves with valve 54 polarized to permit passage of fluid out of cylinder 56 and valve 55 polarized to allow passage of fluid into cylinder 56. Valves 54 and 55 are electrically controllable to pass fluid in one direction or to block flow in both directions and are mechanically adjustable to control the resistance they offer in the open condition.

Limit switches 58 and 59 located at opposite ends of cylinder 46 are operated by piston 57 as it reaches a position at the end of the cylinder. Thus, when piston 57 reaches the left end of cylinder 56, limit switch 58 is operated, its contacts being connected via line 61 to a control mechanism 62 located on or inside the housing of unit 41, the operation of switch 58 thereby causing the hydraulic motor to reverse direction, and also valve 55 to close and valve 54 to open, whereupon fluid is pumped out of cylinder 56 via valve 54 and line 52, thereby causing piston 57 to move toward the right. When piston 57 nears the right-hand end of cylinder 56, switch 59 is operated, its operation causing the hydraulic motor to reverse again and causing valve 55 to open and valve 54 to close so that fluid now enters cylinder 56 via line 53 and valve 55, thereby causing piston 57 to be driven leftward again toward switch 58. The piston 57 is thus seen to be driven back and forth within cylinder 56 and its speed may be regulated by adjustment of valves 54 and 55. Switches 58 and 59 can be replaced by switch 67 located on one or the other of the exercise handles (or at other suitable places). It is a spring loaded switch which turns the pump on when subject desires and turns pump off when it is released.

The reciprocal action of piston 57 may be coupled to any of various types of exercise apparatus. As an example, FIG. 2 shows a rope 63 strung over pulleys 64 and 65 and terminated by a handlebar 66. In using such an exercise apparatus the driving actions of the motor is aided in driving the piston 57 toward the right and resisted during piston travel toward the left. Because the motor tends to drive the piston at constant speed, the user of the apparatus experiences a form of isokinetic exercise at a controlled rate, the rate being readily adjustable in either the forward or reverse stroke by means of valve 54 or 55.

FIG. 3 illustrates a modification of the circuit shown in FIG. 1 wherein motor 11 may be a constant speed motor connected through reversing switch 19 to a source of direct current 70. Motor 11 is directly connected through a slip clutch 71 to the gear train 15 with the slip clutch energized by amplifier 17. Amplifier 17 is energized and controlled in the same manner as shown in FIG. 1. In this embodiment, motor 11 is a constant speed motor with its output varied by a slip clutch 71 controlled by the output of amplifier 17.

A wide variety of isotonic or isokinetic exercising actions may thus be driven and controlled by variations of the system illustrated in FIGS. 1-3. Although but two embodiments of the system have been shown, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

Claims

What is claimed is:

1. A feed back controlled electro-mechanical exercising device comprising:

an electric motor comprising a rotor and a pair of input terminals,

a driven means connected to an exercising device,

means for connecting said rotor to said driven means,

a motor controlling amplifier having a pair of input terminals and an output terminal,

a switch comprising a selector means and a pair of terminals, said selector means being connected to one input terminal of said amplifier,

a tachometer actuated as a result of the movement of said rotor,

means for coupling output signals from said tachometer to one terminal of said switch for constant speed motor operation when said selector means is connected thereto,

a voltage divider connecting the other input terminal of said amplifier across a source of electrical potential,

means for connecting the output terminal of said amplifier to one input terminal of said motor,

grounding means comprising a current sensing resistor for connecting the other terminal of said motor and said other terminal of said selector switch to ground,

whereby the output current supplied by said amplifier to said motor increases until motor speed corresponding to the output signal of said tachometer reaches a value corresponding to the setting of said voltage divider,

said selector means when moved to said other terminal receiving signals from said current sensing resistor which is proportional to motor current and hence motor torque, whereby said motor will operate at constant torque independent of load applied to said driven means.

2. The feedback controlled electro-mechanical exercising device set forth in claim 1 wherein:

said means for connecting said rotor to said driven shaft comprises a gear train.

3. The feed back controlled electro-mechanical exercising device set forth in claim 2 wherein:

said selector means comprises a switch arm, and

said voltage divider comprises a potentiometer.

4. The feed back controlled electro-mechanical exercising device set forth in claim 1 wherein:

said motor comprises a direct current motor.

5. The feed back controlled electro-mechanical exercising device set forth in claim 4 in further combination with:

a reversing switch connected across the input and output terminals of said motor for reversing its direction of rotation.

6. The feed back controlled electro-mechanical exercising device set forth in claim 4 in further combination with:

a reversing switch connected across the input terminals of said direct current motor.

7. The feed back controlled electro-mechanical exercising device set forth in claim 2 in further combination with:

a reversing switch connected across the input terminals of said motor,

said motor comprising a direct current motor, and

a sensing switch connected to said gear train and upon predetermined movement of said gear train generating a signal,

the signal of said sensing switch being coupled to said reversing switch for energization thereof.

8. The feed back controlled electro-mechanical exercising device set forth in claim 1 in further combination with:

a second amplifier connected across said current sensing resistor for sensing motor torque,

clutch means connected between said means for connecting said rotor to said driven shaft and said driven means, and

means for connecting the output of said second amplifier to said clutch means for disconnecting said motor from said driven means upon predetermined load conditions.

9. The feed back controlled electro-mechanical exercising device set forth in claim 8 in further combination with:

a voltage control means connected to one terminal of said second amplifier for controlling the point of disconnection of said motor from said driven means by said clutch means.

10. A feed back controlled electro-mechanical exercising device comprising:

an electric motor comprising a rotor and a pair of input terminals connectable across a source of electric power,

a driven means connected to an exercising device,

means for connecting said rotor to said driven means,

a slip clutch coupling said motor to said means,

an amplifier having a pair of input terminals and an output terminal,

a switch comprising a selector means and a pair of terminals, said selector means being connected to one input terminal of said amplifier,

a tachometer actuated as a result of the movement of said rotor,

means for coupling output signals from said tachometer to one terminal of said switch for controlling the operation of said slip clutch when said selector means is connected thereto,

a voltage divider connecting the other input terminal of said amplifier across a source of electrical potential,

means for connecting the output terminal of said amplifier to one input terminal of said slip clutch, the other terminal of said slip clutch being connected to ground,

grounding means comprising a current sensing resistor for connecting the other terminal of said selector switch to ground,

whereby the output current supplied by said amplifier to said slip clutch varies the slippage of said clutch corresponding to the output signal of said tachometer.