Abstract:
This invention relates to an electromechanical arm and accessories which are mountable on a battery powered wheelchair and used to grasp objects in the personal environment of the operator. The device is designed for simplicity of operation and comprises lower arm, mid arm, and forearm components which are rotationally and pivotally interconnected and selectively rotated through the utilization of a controller which is preferably disposed upon the battery powered wheelchair. The accessories include end-effectors (also called grippers), with features that are task specific or for general manipulation, other tools and means of holding tools, baskets, pouches, holders and other means of storing objects and tools, a variety of input devices that are tailored to the needs of the operator, a sleeve for protection, aesthetics, and increased functionality (with pockets and other means of holding objects), and mounting hardware for the electromechanical arm and associated components.

Description:
RELATED APPLICATIONS  
       [0001]    The present application is related to and claims priority from U.S. Provisional Patent Application 60/310,107 filed Aug. 4, 2001. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0002] This invention was made with U.S. Government support under Grant Numbers, HD41287-01, awarded by the National Institutes of Health. The government has certain rights in the invention. 
     
    
     
       CROSS REFERENCE TO RELATED APPLICATIONS  
         [0003]    [0003]                                                       U.S. Pat. No.   Inventor   Award Date                           5,830,160   Reinkensmeyer   Nov. 3, 1998           5,466,213   Hogan, et al.   Nov. 14, 1995           4,936,299   Erlandson   Jun. 26, 1990                        
         BACKGROUND OF THE INVENTION  
         [0004]    People who have experienced a severe stroke often have significant impairment of muscle function of the arms, legs, and hands, resulting in severe disability. Other types of diseases, traumatic accidents, and neurological disorders result in similar deficiencies in strength, coordination, and range of motion. In order to recover or retain functional ability after a stroke or injury, people normally enter into a rehabilitation program at a rehabilitation facility, under the treatment of a physical and/or occupational therapist. Although the invention described here applies to all rehabilitation programs of this type for upper limb therapy, it is described in terms of its applicability to stroke patients because stroke is the number one disability for which rehabilitation services are provided in the United States.  
           [0005]    For upper limb rehabilitation, the nature of the disability requires that the Therapist carry out a program whereby he or she will move the patient&#39;s arms through a range of motion that is comfortable to the patient as appropriate given the level of recovery of their strength and coordination. Typical therapy programs administered by a Therapist can also involve functional tasks and movements using one or both arms. As the patient&#39;s functional ability increases, the Therapist modifies the regiment to provide less assistance, to extend the range of motion, and to increase the types and difficulty of functional tasks. Such a rehabilitation program requires that the Therapist assess the physical ability of the person on an ongoing basis.  
           [0006]    In a rehabilitation program taking place directly after the stroke has occurred, the amount of therapy a person receives is directly related to the severity of the stroke, the region of the brain in which it occurred, the quality and speed of treatment directly following the stroke, and the actual amount of recovery of ability. For these reasons, the assessment by the Therapist, and the ability to alter the range of motion and assistance provided is critical to treating each individual. It is a paradox of the current medical healthcare environment that, increasingly, the amount of therapy a person receives is being limited by the number of sessions for which a reimbursement will be made and not necessarily on the level of recovery that has been achieved.  
           [0007]    It is an objective of the present invention to provide a device that may be used as a tool by a therapist whereby the therapist can assess the recovery of the patient, and then utilize the present invention to assist the patient with the repetitive motions of the therapy. In this scenario, one therapist can work with a multitude of patients all utilizing the present invention to facilitate movement of the arms through the normal ranges of motions. The present invention utilizes robotic technology, including force and position sensors, to measure the interaction of the patient with the device and to modify the amount of assistance, or resistance, according to the measured information, similar to the actions of a Therapist in a typical rehabilitation program.  
           [0008]    There are generally four other devices that have been developed in the context of research projects, or modest commercialization efforts, that also make use of robotics technology to facilitate stroke rehabilitation.  
           [0009]    MIME, Machiel Van der Loos, Peter Lum, Chuck Burgar, VA Rehabilitation R&amp;D Center, Palo Alto, Calif. MIME is an experimental test rig that provides bi-manual therapy according to four control modes. The concept for the present invention and the motions of the device described herein are based on the four control modes first developed for MIME. The MIME system is an experimental test rig using a commercial robot and a six degree of freedom digitizer to perform the therapeutic activity, and thus it requires a complex controller and control software and is excessively expensive to be practical as a product. The mechanical system is also large and although many safety features have been built into the system, its appearance is sometimes uncomfortable for both the patients and the operators.  
           [0010]    The following references provide further information about the MIME device:  
           [0011]    Lum P S, Burgar C G, Kenney D, Van der Loos H F M. Quantification of force abnormalities during passive and active-assisted upper-limb reaching movements in post-stroke hemiparesis. IEEE Transactions Biomedical Engineering 46(6):652-62, 1999.  
           [0012]    Lum P S, Van der Loos H F M, Shor P, Burgar C G. A robotic system for upper-limb exercises to promote recovery of motor function following stroke. Proceedings, 6 th  International Conference on Rehabilitation Robotics ICORR′99;Jul. 1-2, 1999 Stanford, Calif. p. 235-9.  
           [0013]    Burgar C G, Lum P S, Shor M, Van der Loos H F M. Rehabilitation of upper limb dysfunction in chronic hemiplegia: Robot-assisted movements vs. conventional therapy. Arch Phys Med Rehabil 80(9) :1121, 1999.  
           [0014]    ARM Guide, David Reinkensmeyer, Department of Mechanical Engineering, University of California at Irvine, and the Rehabilitation Institute of Chicago. The ARM Guide is a one degree of freedom electromechanical system that supports single arm movement for the purpose of stroke therapy. The ARM Guide, however, cannot be used for bi-manual therapy as a single degree of freedom system.  
           [0015]    The following references provide further information about the ARM Guide device:  
           [0016]    Reinkensmeyer; David J., Movement guiding system for quantifying diagnosing and treating impaired movement performance. U.S. Pat. No. 5,830,160, Nov. 3, 1998.  
           [0017]    MIT-Manus, Neville Hogan, Department of Mechanical Engineering, MIT. MIT Manus is a robot that provides upper limb therapy in a plane. This system is based on a particular force control algorithm and uses video games to facilitate interaction of the patient with the therapy. This system, however, is not a single degree of freedom device, and cannot be used to carry out bi-manual therapy as such.  
           [0018]    The following references provide further information about the MIT-Manus device:  
           [0019]    Hogan, et al., Interactive robotic therapist. U.S. Pat. No. 5,466,213, Nov. 14, 1995.  
           [0020]    Therapy Robot, Bob Erlandson, Wayne State University, This system consists of a light industrial robot that moves a target to different positions in front of a patient. The patient receives therapy through the activity of reaching out and touching the target as it is moved to different locations by the robotic device. This system, however, cannot support the weight of the patient, it is not a single degree of freedom device, and cannot be used for bi-manual therapy as such.  
           [0021]    The following references provide further information about the Therapy Robot device:  
           [0022]    Erlandson; Robert F., Method and apparatus for rehabilitation of disabled patients. U.S. Pat. No. 4,936,299, Jun. 26, 1990.  
         BRIEF SUMMARY OF THE INVENTION  
         [0023]    This invention is a device to carry out stroke therapy ranges of motion on a human user, including both actively assisting the motion of the user or actively resisting the motion of the user. It is differentiated from other devices in this field because it combines the following characteristics in one device:  
           [0024]    1. Bi-manual operation: This device is designed to accommodate support of both arms and to provide a device to facilitate therapy programs that make use of force and position information from both arms. This is not exclusive, however. The novelty is that the device can be used for single arm therapy as well as dual arm therapy.  
           [0025]    2. Single degree of freedom system: The present invention requires a single drive shaft which engages the motor, brake, position sensor, and drive system which operates the bi-manual motion of the device. This single degree of freedom approach significantly simplifies the cost, manufacture, and control of the system.  
           [0026]    3. Detailed mechanical design elements and configuration: The present invention may be adjusted so that the arms are moved through a multitude of directions. The ability to manually and rigidly reconfigure the vector of the arm motion is a unique aspect of this device.  
           [0027]    4. Movement out of a horizontal plane: The present invention permits movement of the arm out of a horizontal plane. The arms may be guided to move up or down at various angles of elevation and rotation from the patient.  
           [0028]    5. Range of modes: The present invention may operate in several modes including, carrying the limb or limbs through a range of motion with no assistance from the patient (referred to as passive mode), moving the limb through a range of motion after sensing a correct movement intention of the patient, adjusting the amount of assistance to the patient while moving the limb or limbs through a range of motion with the amount of assistance based on the strength of the motion contributed by the patient, and resisting the movement of the patient along the movement direction in order to provide resistance training for the patient.  
           [0029]    6. Adapting and responding to individual patient ability levels: The modes as described above are all facilitated through the use of sensor information, namely force measurements at the location where the arm rests on each of the guides, and the position of the guide along the track as measured by the rotation of the single drive shaft. The force and position information is used to determine the appropriate range of motion, number of repetitions, and force and safety thresholds.  
           [0030]    7. Replication of therapy motions: The mechanical and software elements of the system allow it to be used to replicate the ranges of motion and application of forces applied by a physical therapist during rehabilitation therapy carried out after a stroke.  
           [0031]    8. Provides quantitative data: The present invention consists of force and position sensors, which provide an objective, means of measuring quantitatively the range of motion, force application, force profile, and other indicators of the limbs&#39; performances. This capability has the potential to provide a new standard whereby therapists and physicians can communicate about the status of an individual&#39;s disability through new quantitative data.  
           [0032]    It is envisaged that this device may be utilized in the clinic under several scenarios:  
           [0033]    1. One physical therapist monitoring several patients at one time using multiple devices.  
           [0034]    2. Independent use in a clinic by a patient to extend the amount of therapy time for that patient.  
           [0035]    3. Physical therapist assumes the role of managing the rehabilitation through program of device use and monitoring of measured and derived values. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0036]    These as well as other features of the present invention will become more apparent upon reference to the drawings wherein:  
         [0037]    [0037]FIG. 1 is a perspective view of the preferred embodiment of the machine for upper limb physical therapy, showing all components of the present invention;  
         [0038]    [0038]FIG. 2 is a perspective view of the support structure components comprising the machine for upper limb physical therapy of the present invention;  
         [0039]    [0039]FIG. 3 is a perspective view of the slide arm assembly Number  1  comprising the machine for upper limb physical therapy of the present invention;  
         [0040]    [0040]FIG. 4 is a perspective view of the slide arm assembly Number  2  comprising the machine for upper limb physical therapy of the present invention;  
         [0041]    [0041]FIG. 5 is a perspective view of the cross member assembly comprising the machine for upper limb physical therapy of the present invention;  
         [0042]    [0042]FIG. 6 is a perspective view of sliding platform Number  1  comprising the machine for upper limb physical therapy of the present invention;  
         [0043]    [0043]FIG. 7 is a perspective view of sliding platform Number  2  comprising the machine for upper limb physical therapy of the present invention;  
         [0044]    [0044]FIG. 8 is a plan view of the motor clutch assembly comprising the machine for upper limb physical therapy of the present invention;  
         [0045]    [0045]FIG. 9 is a cross section view of the motor clutch assembly comprising the machine for upper limb physical therapy of the present invention;  
         [0046]    [0046]FIG. 10 is a perspective view of the drive system comprising the machine for upper limb physical therapy of the present invention;  
         [0047]    [0047]FIG. 11 is two perspective views of the support structure components in various positions comprising the machine for upper limb physical therapy of the present invention;  
         [0048]    [0048]FIG. 12 is a block diagram of the preferred embodiment of the control system and sensing elements comprising the machine for upper limb physical therapy of the present invention;  
         [0049]    [0049]FIG. 13 is a block diagram of the control modes for the control system and sensing elements comprising the machine for upper limb physical therapy of the present invention; 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0050]    Referring now to the drawings wherein the showings are for purposes of illustrating a preferred embodiment of the present invention only, and not for purposes of limiting the same, FIG. 1 perspectively illustrates the machine for upper limb physical therapy  10  constructed in accordance with the preferred embodiment of the present invention. Referring now to FIGS. 1 and 2, the machine for upper limb physical therapy  10  generally comprises a control system  100  with display interface  120 ; and support structure components comprising of Dual arm support assemblies  14  and  16 , cross member assembly  18 , support structure  12 , drive system  24  and user interfaces  28 L and  28 R.  
         [0051]    Referring now to FIGS. 2, 3 and  4  the dual arm support assemblies  14  and  16  each includes a linear track  86  and  88  respectively that hold sliding platforms  20  and  22  respectively. The sliding platforms  20  and  22  have means for connecting braces  28 L and  28 R that can hold the arms of a user firmly. The sliding platforms  20  and  22  are capable of sliding movement along the linear tracks  86  and  88  through intimate contact of the rollers  42 , thereby carrying the user interface braces  28 L and  28 R along a linear path. Referring now to FIGS. 6 and 7 the sliding platforms  20  and  22  each have a carriage  36  which provides structural support for the rollers  42 , a provision for easily mounting either mounting plate  34  or mounting plate  48 . The carriage  36  also has means for attaching to the drive system  24  through brackets  44  and  46  which are securely attached to carriage  36  and operatively attached to the drive system  24  through drive system attachment blocks  74  and  76 .  
         [0052]    Mounting plate  34  is used for attaching force sensor  30 , which measures three orthogonal components of force and three orthogonal components of torque. Either of the user interface braces  28 L or  28 R is mounted to force sensor  30  through a quick connect ball joint  40  which is operatively attached to force sensor  30  by means of mounting plate  38 . The force sensor  30  measures the forces exerted by the user&#39;s impaired arm on the system. In addition, mounting plate  48  is used for attaching force sensor  32 , which measures one component of force in the direction of linear movement of sliding platforms  20  and  22  and in turn the forces exerted by the user&#39;s unimpaired arm on the system. Either of the user interface braces  28 L or  28 R is mounted to the input side of force sensor  32  through quick connect ball joint  40  which is attached to mounting block  50 . Mounting block  50  is operatively coupled to force sensor  32  and linear bearing  49 , which only allows sliding movement in the direction of the measurement force of force sensor  32 . Linear bearing  49  is also firmly attached to mounting plate  48 .  
         [0053]    Referring now to FIGS. 2 and 5 support base  12  provides a structure that holds the dual arm supports  14  and  16 . Support base  12  rests on the ground and in the preferred embodiment, dual arm support assemblies  14  and  16  are connected to cross member assembly  18  through the attachment of the yaw rotation plates  94 L and  94 R. By loosening the yaw rotation plates  94 L and  94 R the dual arm support assemblies  14  and  16  are selectively articulable in the yaw direction to angled orientations of approximately 0 degrees to 345 degrees. Cross member assembly  18  is pivotally connected to the support base  12  at the pivot joints  90 L and  90 R. Cross member assembly  18  is also pivotally and linearly attached at  92 L and  92 R as well as  96 L and  96 R.  
         [0054]    As will be recognized, since cross member assembly  18  serves to directly interface dual arm support assemblies  14  and  16  to support base  12 , the rotation of cross member assembly  18  will cause the concurrent rotation of the dual arm support assemblies  14  and  16 . By loosening the pivot joints  90 L,  90 R,  92 L,  92 R,  96 L and  96 R the dual arm support assemblies  14  and  16  are selectively articulable in the pitch direction to angled orientations of approximately 0 degrees to 170 degrees. Referring to FIG. 11, two possible configurable positions that the dual arm support assemblies  14  and  16  can be manually reconfigured may be seen. Referring again to FIG. 2, the support members  98 L and  98 R have a sliding connection between support base  12  and support members  98 L and  98 R. By loosening the sliding joints of support members  98 L and  98 R the dual arm support assemblies  14  and  16  can also be manually reconfigured to change the height of the plane in which they sit.  
         [0055]    Referring now to FIGS. 8, 9 and  10  the sliding platforms  20  and  22  are driven in a linear movement by means of a motor M 1  via a crown-toothed electric clutch  54  and drive system  24 . The motor M 1  and crown-toothed electric clutch  54  are connected to the cross member assembly  18  via motor mounting block  52 . Drive system  24  includes a series of drive shafts  56 ,  70  and  72 ; chains  58 ,  60 ,  62 ,  64 ,  66 , and  68 ; and sprockets  80  and  82  connected as follows. The output drive shaft of the motor M 1  is operatively connected to the crown-toothed electric clutch  54 , and the crown-toothed electric clutch  54  will in turn rotate the drive shaft  56  as long as the load resistance torque on the drive shaft  56  does not exceed 50 inch-pounds. A load resistance torque greater than 50 inch-pounds will cause the crown-toothed electric clutch  54  and drive shaft  56  to slip causing the sliding platforms  20  and  22  to move freely with no resistance along the linear tracks  86  and  88 .  
         [0056]    As shown in FIG. 10 a single sprocket  80  is operatively coupled to drive shaft  56 . Drive shaft  56  extends through the cross member  85  and is also operatively attached to the input shaft of potentiometer  84 . The body of potentiometer  84  is fixed to cross member  85 . The potentiometer  84  changes resistance as drive shaft  56  is rotated. The position of the sliding platforms  20  and  22  along the linear tracks  86  and  88  can be measured by monitoring the change in resistance of potentiometer  84 .  
         [0057]    Referring now to FIGS. 3, 5 and  10  the single sprocket  80  on drive shaft  56  drives chain  58 , which in turn drives dual sprocket  82  on the end of drive shaft  70 . Drive shaft  70  extends through the cross member  85  and linear track  86 , and is also operatively attached to another sprocket  80  on the opposite end of drive shaft  70 . The single sprocket  80  on the opposite end of drive shaft  70  drives chain  64 , which in turn drives another dual sprocket  82  which is mounted internally to linear track  86 . The dual sprocket  82  which is mounted internally to linear track  86  drives chain  62  which is attached to sliding platform  20  via drive system attachment block  74 .  
         [0058]    Referring now to FIGS. 4, 5 and  10  The dual sprocket  82  on the end of drive shaft  70  also drives chain  60  which drives another sprocket  80  on the end of drive shaft  72 . Drive shaft  72  extends through the cross member  85  and linear track  88 , and is also operatively attached to another sprocket  80  on the opposite end of drive shaft  72 . The single sprocket  80  on the opposite end of drive shaft  72  drives chain  66 , which in turn drives another dual sprocket  82  which is mounted internally to linear track  88 . The dual sprocket  82  which is mounted internally to linear track  88  drives chain  68  which is attached to sliding platform  22  via drive system attachment block  76 .  
         [0059]    As will be recognized, since the sliding platforms  20  and  22  on the linear tracks  86  and  88  respectively, are each connected to drive system  24 , and all of the sprockets in drive system  24  are of the same diameter, the relative motion between sliding platforms  20  and  22  will be fixed. Each sliding platform  20  and  22  is constrained to move at the same time in the same direction along the linear tracks  86  and  88 , either towards or away from the user.  
         [0060]    Referring now to FIG. 12 the machine for upper limb physical therapy  10  generally comprises a control system  100  with display interface  120  and input interface  122  used to control the dual arm support assemblies  14  and  16  through user interfaces  28 L and  28 R.  
         [0061]    Referring now to FIGS. 12 and 13, the present invention is able to operate in several control modes that define the interaction with the patient that occurs at the patient inputs  28 R and  28 L. The device receives inputs  102  that define the range of motion, number of repetitions of movement, force thresholds, and mode of operation into controller  100 . The controller monitors the output sensor information from position sensor  84  and force sensors  30  and  32  and determines the output signals to motor M 1  and clutch  54 .  
         [0062]    Referring still to FIG. 13, operation of the present invention occurs as follows for each control mode. In passive mode, the input  102  includes a target movement distance, a movement velocity, a force safety threshold, and a number of repetitions of movement. Upon initiation of the program, the invention will move the patient&#39;s arm at  28 R or  28 L along the dual arm support assemblies  14  and  16  from the starting location to the target distance and back to the starting location a number of times equal to the input  102  for the number of repetitions. The controller will monitor the force sensor info from  30  and  32  and will provide an output request for the motor M 1  to move at the target speed until the position target is reached, and stop motion of the system if the safety threshold for these force values are exceeded. The user may assist during this motion, but the purpose of this mode is to provide range of motion exercising for the patient without any active use of the muscle.  
         [0063]    Again referring to FIG. 13, in active-assisted mode, the input  102  includes a target movement distance, a movement velocity, an active force threshold, a force safety threshold, and a number of repetitions of movement. Upon initiation of the program, the controller will monitor the force sensor  30  at the patient interface  28 R or  28 L and compares the force generated in the direction of motion along the dual arm support assemblies  14  and  16  with the active force threshold. When the force in the direction of motion exceeds the active force threshold, the controller initiates outputs to the motor M 1  to initiate movement of the left arm support assembly  14  and/or Right arm support assembly  16  and after motion occurs, the controller  100  monitors the device as if it were operating in the passive mode as described above until the Left arm support assembly  14  and/or Right arm support assembly  16  returns to the starting location. For the next repetition, the controller  100  again monitors the force in the direction of motion and initiates motion when this force exceeds the active force threshold. This sequence continues until the controller  100  identifies that the target number of repetitions has been achieved. During the motion of the dual arm support assemblies  14  and  16 , the user may actively support the movement, but the movement forces are not used by the controller  100  in determining the output to motor M 1 . If a force exerted at  28 R or  28 L exceeds the safety force threshold, then the controller  100  will provide an output to the clutch  54  that will disengage the system from the user. The purpose of the active-assisted mode is for the patient to practice correctly initiating a movement in the direction of motion.  
         [0064]    Referring still to FIG. 13, in active-constrained mode, the input  102  includes a target movement distance, a movement velocity, an active force resistance, a force safety threshold, and a number of repetitions of movement. Upon initiation of the program, the patient will actively engage the left arm support assembly  14  or right arm support assembly  16  at the patient interface  28 R or  28 L and will move the users arm along the arm support assemblies  14  and  16 . The controller will monitor the force sensor  30  at the patient interface  28 R or  28 L and compare the force generated in the direction of motion along the dual arm support assemblies  14  and/or  16  with the active force resistance. The controller  100  will provide an output request to the motor M 1  to oppose the motion of the users arm and thus create a resistance force at the Patient Interfaces  28 R or  28 L. The resistance force will be low enough so that the patient may overcome it and thus a form of resistance strength training will take place. If the force in the direction of motion exceeds the active resistance force, the controller  100  initiates outputs to the motor M 1  to reduce the opposing motion. When the dual arm support assemblies  14  or  16  reach the target distance provided by input  102 , the patient will return the sliding platform  20  or  22  to the starting point and the controller  100  will monitor the force at the patient interface  28 R or  28 L and will provide outputs to the motor M 1  to resist this motion until the active resistance force is achieved. This sequence continues until the controller identifies that the target number of repetitions has been achieved. If a force exerted at  28 R or  28 L exceeds the safety force threshold, then the controller  100  will provide an output to the clutch  54  that will disengage the system from the user. The purpose of this mode is to provide the patient with the opportunity to practice resistance strength training.