WO2001037940A1

WO2001037940A1 - Trainable therapeutic exercise device with force feedback

Info

Publication number: WO2001037940A1
Application number: PCT/US2000/042245
Authority: WO
Inventors: Kenneth M. Bueche; David W. Peterson; Robert W. Schroeder
Original assignee: Bueche Kenneth M; Peterson David W; Schroeder Robert W
Priority date: 1999-11-24
Filing date: 2000-11-21
Publication date: 2001-05-31
Also published as: AU3083601A

Abstract

A therapeutic and rehabilitation exercise device (10) with force feedback and dynamic force control that is fully programmable, that can determine the force exerted by a patient while using the device, and that can dynamically alter the force that must be exerted by the patient throughout the range of motion of the device. The exercise device includes a moveable component (22) that can be moved by a patient while performing a prescribed exercise and a closed loop control system coupled with the moveable component for aiding or resisting movement of the component by the patient and for selectively setting at least one parameter related to the movement of the component.

Description

TRAINABLE THERAPEUTIC EXERCISE DEVICE WITH FORCE FEEDBACK

BACKGROUND OF THE INVENTION

1. FIELD OF THE INVENTION

The present invention relates to therapeutic and rehabilitation exercise devices. More particularly, the invention relates to a therapeutic exercise device with force feedback and dynamic force control that is fully programmable, that can determine the force exerted by a patient while using the device, and that can dynamically alter the force that must be exerted by the patient throughout the range of motion of the device.

2. DESCRIPTION OF THE PRIOR ART Many prior art types of therapeutic and rehabilitation exercise devices have been developed for use by patients in exercising injured body parts. These devices typically include a moveable component such as a lever arm, squeezable bulb, or rotating knob that can be moved by the patient as part of an exercise regime and a resistive component such as a spring, friction device or compressible material for resisting movement of the moveable component.

These prior art therapeutic and rehabilitation exercise devices suffer from several limitations that limit their utility. For example, the resistance in these devices is typically fixed, requiring a patient to use several such devices each having a different resistance as the patient is able to exert more force on the moveable component as his or her injuries improve.

Another limitation is that the resistive components of these prior art devices provide resistance that is constant over their entire range of motion. This is a problem because some patients cannot exert enough force to begin movement of an exercise device but are able to exert more force further into the range of motion of the device. Some prior art therapeutic and rehabilitation exercise devices have variable resistance mechanisms; however, these mechanisms are typically mechanical in nature and require mechanical and structural adjustments to vary their resistance.

Another limitation of prior art therapeutic and rehabilitation exercise devices is that they cannot accurately determine the force that is exerted by a patient while the patient is using the device. A further limitation of prior art therapeutic and rehabilitation exercise devices is that they are typically large, cumbersome, and too expensive for patients to purchase for use at home. Therefore, the devices typically can only be used during office visits to the patient's doctor or therapist. Yet another limitation of prior art therapeutic and rehabilitation exercise devices is that their use cannot be monitored and verified outside the presence of a doctor, therapist, or other medical professional. Therefore, medical professionals have no way of verifying that prescribed exercise regimes are actually being performed while a patient is at home and thus cannot accurately gauge the effectiveness of a prescribed exercise regime.

OBJECTS AND SUMMARY OF THE INVENTION

The present invention solves the above-described problems and provides a distinct advance in the art of therapeutic and rehabilitation exercise devices. More particularly, the present invention provides an exercise device with force feedback and dynamic force control that is fully programmable, that can determine the force exerted by a patient while using the device, and that can dynamically alter the force that must be exerted by the patient throughout the range of motion of the device.

The exercise device of the present invention broadly includes a moveable component that can be moved by a patient while performing a prescribed exercise and a closed loop control system coupled with the moveable component for aiding or resisting movement of the component by the patient and for selectively setting at least one parameter related to the movement of the component. The parameter may be, for example, the force applied by the closed loop control system to aid the movement of the moveable component by the patient; the force applied by the closed loop control system to resist movement of the moveable component by the patient; or the range of motion of the moveable component.

In preferred forms, the closed loop control system includes a servomotor for aiding or resisting the movement of the moveable component by the patient; a power unit for applying a selected current to the servomotor so that the servomotor provides a selected amount of force to aid or resist the movement of the component; and a control assembly coupled with the power unit for controlling current delivery to the servomotor. The closed loop control system may also include a position sensor operably coupled between the moveable component and the control assembly for monitoring the position of the moveable component and for generating corresponding signals for delivery to the control assembly for use in controlling current delivery to the servomotor. These and other important aspects of the present invention are described more fully in the detailed description below.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

A preferred embodiment of the present invention is described in detail below with reference to the attached drawing figures, wherein:

Fig. 1 is a schematic diagram of a therapeutic exercise device constructed in accordance with a preferred embodiment of the preferred invention.

Fig.2 is a perspective view of a portion of the therapeutic exercise device. Fig. 3 is a perspective view illustrating the coupling of the therapeutic exercise device with an external computer.

Fig.4 is a circuit diagram illustrating a method for obtaining force feedback data from the therapeutic exercise device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Turning now to the drawing figures, a therapeutic exercise device 10 constructed in accordance with a preferred embodiment of the invention is illustrated. The exercise device is configured for use by a patient to exercise an injured body part pursuant to a prescribed exercise regime and broadly includes an end-effector 12, a power unit 14, and a control assembly 16. The exercise device may be coupled with an external computer 18 operable by a therapist or other medical professional for programming as illustrated in Fig. 3 and as described in more detail below.

In more detail, the end-effector 12, which is best illustrated in Fig. 2, is the component of the exercise device 10 that is manipulated by a patient for exercising an injured body part. The end-effector may be of any size and shape for exercising different parts of the body. For example, the illustrated end-effector is configured for exercising the joints in a person's hand. Larger end-effectors may be configured for exercising other body parts such as a person's hip or knee. Regardless of size, however, each end-effector broadly includes a moveable component 20 that can be moved by a patient while performing a prescribed exercise and a servomotor 22 for aiding or resisting the movement of the moveable component.

The moveable component 20 in the illustrated embodiment is a lever or arm that is directly or indirectly attached to the output shaft of the servomotor 22. A gear assembly 24 may be coupled between the moveable arm and the servomotor output shaft to create a mechanical advantage and thereby reduce the required motor size. A stationary arm or lever 26 may be attached to the body of the gear assembly or servomotor for preventing movement of a patient's hand while the patient moves the moveable component with his or her fingers. The servomotor 22 is preferably a permanent magnet, DC motor but may be other types of servo assemblies. The size and rating of the servomotor depends upon the size of the moveable component 20 and the body part that is to be exercised. For example, a smaller servomotor is used for the device illustrated in the drawing figures and a larger servomotor would be used for a device designed for exercising a patient's legs or arms. Examples of servomotors that may be used with the present invention are the ones manufactured by Pittman or Micro Mo Electronics.

In preferred forms, a position sensor 28 such as an incremental encoder is operably coupled with the servomotor 22 for monitoring the position of the moveable component 20 and for generating corresponding position signals that are delivered to the control assembly 16 as described in more detail below. The position sensor is used to count repetitions or cycles of an exercise and to measure the range of motion of the moveable component as it is moved by the patient during an exercise regime. Examples of position sensors that may be used with the present invention are the ones manufactured by Hewlett Packard. The power unit 14 provides a selected current to the servomotor 22 in response to control signals from the control assembly 16. The preferred power unit 14 includes a power supply 30 that connects to a conventional A.C. power outlet and converts A.C. current to D.C. current and a pulse-width modulation amplifier 32 or linear amplifier coupled with the power supply which supplies a selectable width, reversible current to the servomotor. The power unit may be either a stand-alone unit for small hand-held end-effectors or may be an integral part of larger end-effectors.

The control assembly 16 controls the delivery of current to the servomotor 22 in response to custom programming as described in the operation section below. The preferred control assembly includes a central processing unit 34 such as a microprocessor, microcontroller, or other computing device and a motion controller 36. The control assembly is operably coupled between the position sensor 28 of the end effector 12 and the power unit 14 for receiving the position signals from the position sensor and for providing control signals to the power unit as described in more detail below. Examples of central processing that may be used with the present invention are the ones manufactured by Intel or Motorola. Examples of motion controllers that may be used with the present invention are the ones manufactured by Intel or Motorola.

The servomotor 22 , power unit 14, and control assembly 16 cooperatively make up a closed loop control system for controlling, setting, and adjusting at least one parameter related to the movement of the moveable component 20 of the end-effector 12 by a patient. For example, as described in more detail below, the closed loop control system may set the force that must be exerted by the patient to move the moveable component, the force that is applied by the servomotor to aid movement of the moveable component, or the range of motion of the moveable component.

The preferred closed loop control system includes the illustrated electromechanical components, but may also consist of other types of closed loop control systems. For example, the closed loop control system may consist of a hydraulic or pneumatic servo system. Operation

The therapeutic exercise device 10 can be used for either passive or active therapeutic exercises. In passive mode, the device automatically exercises a joint or muscle without the patient applying any force throughout the range of motion. In active mode, the device will apply a resistive force against movement created by the patient.

The exercise device 10 is configured to be used at home by a patient; however, it is preferably programmed by a therapist or other medical professional before being used. As illustrated in Fig. 3, the device can be interfaced with an external computer 18 or work station operated by a doctor, therapist, or other medical professional for this purpose. When connected to the external computer, the control assembly 16 can be fully programmed by the computer under the direction of the therapist. This permits the therapist and patient to custom program the exercise device with an exercise regime that best suits the patient's particular needs. Once the exercise device is programmed, the patient takes it home and uses it as prescribed until the patient's next visit with the therapist.

The exercise device 10 may be programmed to provide various custom exercise regimes for patients. For example, the device may be programmed to mix both active and passive exercises. In this mode, a patient is required to initially exert a selected force to move the moveable component 20 against resistance provided by the servomotor 22 to flex a joint to a prescribed range of motion. Then, once the range of motion limit is reached, the control assembly 16 causes the servomotor to pause momentarily and then apply a force in the opposite direction to straighten the joint.

The exercise device 10 may also be programmed to provide dynamic loading. Dynamic loading allows a medical professional to program a force versus displacement curve into the control assembly 16 so that the servomotor 22 provides a low amount of resistance at the beginning of a range of motion and a higher amount of resistance at the end of the range of motion. This allows a patient to exert a low force at the beginning of flexure of a body part and to then gradually increase his or her exerted force throughout the remainder of the range of motion. Dynamic loading greatly reduces joint stress during exercise.

The exercise device 10 may also be programmed to select the force a patient must exert to move the moveable component 20 when the device is operated in the active mode. Similarly, the device may be programmed to select the force applied by the servomotor 22 to aid the movement of the moveable component when the device is operated in the passive mode.

The exercise device 10 may also be programmed to select the range of motion of the moveable component 20 for a particular exercise. Selecting the range of motion may be accomplished in several ways. One method is to prevent movement of WO 01/37940 PCT/TJSOO/42245

-7- the moveable component when a limit is reached by detecting such limit with the position sensor 28 and then providing adequate current to the servomotor 22 to prevent further movement of the moveable component. Another method is to remove all current delivery to the servomotor so that the patient may freely move the moveable component beyond the range of motion limit but without any resistive force.

The exercise device 10 is also operable to provide force feed-back information such as the force that is actually exerted by a patient while moving the moveable component 20. Obtaining force feed-back information may be accomplished by calibrating the exercise device such that, at a given pulse width modulation current provided by the power unit, the required force exerted by the patient to move the moveable component is known. Alternately, such force feed-back information can be obtained by mounting strain gauges on the fixed component and again calibrating the device so that the relationship between force exerted by the patient and measured strain is determined. Yet another method for obtaining such force feed-back information is to measure the current supplied to the servomotor with a conventional current measuring device 38 as depicted in Fig. 4.

The control assembly 16 also preferably includes memory or can access external memory for storing historical data relating to the use of the exercise device 10. This historical data may later be downloaded to the therapist's computer 18 when the patient returns to the therapist for an office visit. For example, the control assembly 16 may be programmed to record the frequency and time of use of the exercise device, the number of repetitions of a particular exercise, the range of motion that the patient is able to achieve while moving the moveable component over time, the amount of force exerted by the patient on the moveable component over time, etc. This historical information can be used by the therapist or other medical professional to determine the patient's progress and to monitor whether the patient is actually following the prescribed exercise routine and other compliance issues.

The historical data stored in the memory of the control assembly 16 may also be used to dynamically alter a prescribed exercise regime. For example, if the historical information indicates that a patient's range of motion or strength is improving dramatically from day to day, the control assembly may be programmed to automatically increase the current delivery to the servomotor 22 to increase the amount of force that must be exerted by the patient to move the moveable component 20. Similarly, the control assembly may increase the range of motion of the moveable component as the patient's range of motion increases over time.

Although the invention has been described with reference to the preferred embodiment illustrated in the attached drawing figures, it is noted that equivalents may be employed and substitutions made herein without departing from the scope of the invention as recited in the claims.

Having thus described the preferred embodiment of the invention, what is claimed as new and desired to be protected by Letters Patent includes the following:

Claims

CLAIMS:

1. A therapeutic exercise device comprising: a moveable component that can be moved by a patient while performing a prescribed exercise; and a closed loop control system coupled with the moveable component for aiding or resisting movement of the component by the patient and for selectively setting at least one parameter related to the movement of the component.

2. The therapeutic exercise device as set forth in claim 1 , the parameter being selected from the group consisting of: force applied by the closed loop control system to aid the movement of the moveable component by the patient; force applied by the closed loop control system to resist movement of the moveable component by the patient; and range of motion of the moveable component.

3. The therapeutic exercise device as set forth in claim 1 , the closed loop control system including - a servomotor for aiding or resisting the movement of the moveable component by the patient; a power unit for applying a selected current to the servomotor so that the servomotor provides a selected amount of force to aid or resist the movement of the component; and a control assembly coupled with the power unit for controlling current delivery to the servomotor.

4. The therapeutic exercise device as set forth in claim 3, the closed loop control system further including a position sensor operably coupled between the moveable component and the control assembly for monitoring position of the moveable component and for generating corresponding signals for delivery to the control assembly for use in controlling current delivery to the servomotor.

5. The therapeutic exercise device as set forth in claim 4, the position sensor including an incremental optical encoder coupled with the servomotor.

6. The therapeutic exercise device as set forth in claim 3, the servomotor including a permanent magnet direct current motor.

7. The therapeutic exercise device as set forth in claim 3, the power unit including a power supply and a pulse width modulation amplifier coupled with the power supply for applying a selectable current to the servomotor.

8. The therapeutic exercise device as set forth in claim 3, the control assembly including a motion controller and a processor.

9. The therapeutic exercise device as set forth in claim 3, the processor including a computer program stored in computer readable memory for receiving instructions for adjusting the parameter related to the movement of the moveable component.

10. The therapeutic exercise device as set forth in claim 1 , the closed loop control system including a hydraulic system.

11. The therapeutic exercise device as set forth in claim 1 , the closed loop control system including a pneumatic servo system.

12. The therapeutic exercise device as set forth in claim 9, the control assembly further including memory for storing information relating to the movement of the moveable component by the patient.

13. The therapeutic exercise device as set forth in claim 12, the information being selected from the group consisting of: force applied by the patient on the moveable component while moving the moveable component; range of motion of the moveable component; number of times the patient moves the moveable component in a time period; and time periods in which the patient moves the moveable component.

14. A therapeutic exercise system comprising: an exercise device including - a moveable component that can be moved by a patient while performing a prescribed exercise; and a closed loop control system coupled with the moveable component for aiding or resisting movement of the component by the patient and for selectively setting at least one parameter related to the movement of the component; and a computer assembly operable by a therapist or other medical professional assisting the patient, the computer system including a computer program stored in computer readable memory for providing instructions to the closed loop control system for adjusting the parameter related to the movement of the moveable component.

15. The therapeutic exercise system as set forth in claim 14, the parameter being selected from the group consisting of: force applied by the closed loop control system to aid the movement of the moveable component by the patient; force applied by the closed loop control system to resist movement of the moveable component by the patient; and range of motion of the moveable component.

16. The therapeutic exercise system as set forth in claim 14, the closed loop control system including - a servomotor for aiding or resisting the movement of the moveable component by the patient; a power unit for applying a selected current to the servomotor so that the servomotor provides a selected amount of force to aid or resist the movement of the component; and a control assembly coupled with the power unit for controlling current delivery to the servomotor.

17. The therapeutic exercise system as set forth in claim 16, the closed loop control system further including a position sensor operably coupled between the moveable component and the control assembly for monitoring position of the moveable component and for generating corresponding signals for delivery to the control assembly for use in controlling current delivery to the servomotor.

18. The therapeutic exercise system as set forth in claim 17, the position sensor including an incremental optical encoder coupled with the servomotor.

19. The therapeutic exercise system as set forth in claim 16, the servomotor including a permanent magnet direct current motor.

20. The therapeutic exercise system as set forth in claim 16, the power unit including a power supply and a pulse width modulation amplifier coupled with the power supply for applying a selectable current to the servomotor.

21. The therapeutic exercise system as set forth in claim 16, the control assembly including a motion controller and a processor.

22. The therapeutic exercise system as set forth in claim 21 , the processor including a computer program stored in computer readable memory for receiving instructions for adjusting the parameter related to the movement of the moveable component.

23. The therapeutic exercise system as set forth in claim 14, the closed loop control system including a hydraulic system.

24. The therapeutic exercise system as set forth in claim 14, the closed loop control system including a pneumatic servo system.

25. The therapeutic exercise system as set forth in claim 22, the control assembly further including memory for storing information relating to the movement of the moveable component by the patient.

26. The therapeutic exercise system as set forth in claim 22, the information being selected from the group consisting of: force applied by the patient on the moveable component while moving the moveable component; range of motion of the moveable component; number of times the patient moves the moveable component in a time period; and time periods in which the patient moves the moveable component.