Patent Publication Number: US-6334852-B1

Title: Joint movement monitoring system

Description:
RELATED APPLICATIONS 
     This is a continuation of application Ser. No. 09/026,834 filed Feb. 20, 1998, now U.S. Pat. No. 5,980,472. 
    
    
     FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     MICROFICHE APPENDIX 
     A microfiche appendix as Appendix 1 containing a source code of a computer program useful in accordance with the present invention is appended hereto as 3 sheet(s) of microfiche containing 186 frames. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is concerned with the field of monitoring joint movements of a subject. In particular, a preferred joint movement monitoring system includes a carrier configured for wearing by a subject about a wrist thereof and a plurality of position sensors coupled with the carrier for sensing various hand positions of the subject. 
     2. Description of the Prior Art 
     With advances in medical science, it is now better appreciated that repetitive motion can sometimes lead to injury such as carpal tunnel syndrome. In response, devices have been developed to monitor the motions of body parts with respect to a joint. 
     One such device includes a glove with portions of the glove fingers removed and with sensors positioned adjacent the back of the hand. Such a device inhibits natural motion of the fingers and of the hand itself, leading to less realistic data. Moreover, the bulk of the glove is sometimes objectionable by wearers. 
     SUMMARY OF THE INVENTION 
     The present invention solves the prior art problems mentioned above and provides a distinct advance in the state of the art. In particular, the joint movement monitoring system hereof enables the gathering of accurate data using a comfortable appliance and without inhibiting the wearer&#39;s natural movements. 
     The preferred embodiment of the present invention includes a plurality of position sensors, a carrier mounting the sensors and configured for wearing by the subject and for positioning the sensors adjacent the wrist of the subject, and a controller for storing position data received from the sensors and representative of hand positions. In preferred forms, the active components of the sensors are Hall effect sensors mounted on the carrier adjacent the subject&#39;s forearm rather than the subject&#39;s hand. The preferred carrier is an elastic band encompassing the wrist and adjacent portions of the hand and forearm without covering any portion of the fingers of the subject&#39;s hand. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front view of the preferred apparatus in accordance with the present invention showing the cover removed for clarity of illustration and shown being worn by a subject; 
     FIG. 2 is a rear view of the apparatus of FIG. 1 with the cover partially removed for clarity of illustration; 
     FIG. 3 is a right side view of the apparatus of FIG. 1 with the subject&#39;s hand in flexion; 
     FIG. 4 is a view similar to FIG. 3 with the subject&#39;s hand in extension; 
     FIG. 5 is a front view of the apparatus of FIG. 1 with the subject&#39;s hand in radial extension; 
     FIG. 6 is a front view of the apparatus of FIG. 1 with the subject&#39;s hand in ulnar extension; 
     FIG. 7 is a front view of the apparatus of FIG. 1 with the subject&#39;s hand in pronation; 
     FIG. 8 is a view of the apparatus of FIG. 1 with the subject&#39;s hand in supination; and 
     FIG. 9 is an electrical block diagram of the sensors and controller of FIG. 1 further connected with a personal computer. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The drawing figures illustrate preferred joint movement monitoring apparatus  10  in accordance with the present invention. Apparatus  10  broadly includes flexion/extension (up/down) sensor  12 , ulnar/radial deviation (left/right) sensor  14 , pronation/supination (rotation) sensor  16 , carrier  18 , controller  20  and in preferred forms, personal computer  22  (see FIG.  9 ). 
     Carrier  18  is preferably in the form of light weight, elastic band for wearing by a subject and includes wrist section  24  along with adjacent hand section  26  and forearm section  28  for substantially encompassing the respective body parts. Hand section  26  includes thumb hole  30  for positioning and orienting carrier  18  on a subject. As illustrated, carrier  18  is configured to position sensors  12 - 16  without covering any portion of the subject&#39;s fingers. Because of this, carrier  18  does not inhibit free movement of the subject&#39;s fingers, which has been a problem with prior art devices. 
     Carrier  18  also includes wrap-around cover  32   35  (See FIG. 2) for covering and protecting sensors  12 - 16 . Cover  32  is secured using conventional hook-and-eye fasteners  34 . 
     Each sensor  12 - 16  includes an active component and a static component. Each active component includes slide block  36  with a Hall effect sensor contained therein and positioned adjacent rod-receiving, slide opening  38  defined in block  36 . As shown in FIGS. 1-5, each slide block  36  is mounted on forearm section  28  of carrier  18 . 
     The static component is in the form of a sensor rod  39  having one end  40  affixed to carrier  18  and the distal end slidably received in the rod-receiving opening  38  of a corresponding slide block  36 . The distal end of each sensor rod includes cylindrically shaped magnet  42  axially coupled therewith and positioned to slide within slide opening  38 . 
     For sensors  12  and  14 , it will be noted that end  40  of each sensor rod  39  is connected to hand section  26  of carrier  18  and that sensor rod  39  spans wrist section  24  and terminates within a respective slide block  36  mounted to forearm section  28 . Sensor  16  is positioned entirely on forearm section  28 . With this arrangement, the bulk of sensors  12  and  14  is off of the wearer&#39;s hand and does not inhibit the freedom of movement thereof which has been a problem in the prior art. Wires  44  couple each sensor  12 - 16  (and in particular, each Hall effect sensor thereof) with controller  20  by way of plug  46 . 
     Each sensor  12 - 16  is operable for sensing hand positions of the subject as indicated by magnet  42  and for producing position signals representative thereof as discussed further herein. In particular, FIGS. 3 and 4 illustrate the operation of sensor  12  for sensing the extremes of flexion (FIG.  3 ), extension (FIG. 4) and positions therebetween. Similarly, FIGS. 5 and 6 illustrate the operation of sensor  14  for sensing the extremes of radial extension (FIG.  5 ), ulnar extension (FIG. 6) and positions therebetween. 
     As best viewed in FIG. 7, sensor  16  is mounted on forearm section  28  at an angle relative to the axis of carrier  18 . This enables sensor  16  to sense the rotational positions of the wearer&#39;s hand by sensing rotation of the forearm. FIG. 7 illustrates the subject&#39;s forearm in pronation, that is, rotated in one direction and the position of sensor  16 . FIG. 8 illustrates the subject&#39;s forearm rotated in the opposite direction (supination) and the position of sensor  16 . As will now  10  be appreciated, sensors  12 - 16  monitor all six degrees of hand movements illustrated in FIGS. 3-8 and thereby enable monitoring of all possible positions of the subject&#39;s hand. 
     Apparatus  10  is useful for monitoring the positions of a wearer&#39;s hand over time which represents movement and storing position data represented thereof. This data can then be analyzed to determine whether the subject is exposed to repetitive motion injury. 
     In use, the subject dons carrier  18  with sensors  12 - 16  and controller  20  attached thereto. The wearer&#39;s hand is inserted through thumb hole  30  and carrier  18  pulled snugly toward the wearer&#39;s elbow with sensor  12  centrally positioned (see FIG. 7) and with sensor  14  adjacent and aligned with the ulnar. Also, plug  48  is received in connector  48  (FIG. 9) of controller  20 . 
     Referring to FIG. 9, normally open, switch SW 1  is then depressed which activates microcontroller  50  (type 87051). Microcontroller  50  along with the other components of controller  20  and sensors  12 - 16  are powered by a conventional power supply including a battery (not shown) contained within the housing of controller  20 . 
     A computer program (shown in the microfiche appendix included as part of the disclosure hereof) is stored within the internal ROM of microcontroller  50  and controls the operation thereof and thereby the operation of controller  20 . Analog-to-digital converter (A/D)  52  receives the analog position signals from sensors  12 - 16  and converts these to digital position signals for use by microcontroller  50 . Plug  46  is configured to connect with pins  1 - 6  of connector  48 . Pins  8 - 10  are used for serial data transfer as further discussed below. 
     Upon activation by switch SW 1 , beeper  52  sounds a tone, LED  56  is activated indicating that controller  20  is operating, and microcontroller  50  begins sampling the position signals from sensors  12 - 16  at the programmable rate. Microcontroller  50  derives position data representative of the subject&#39;s hand positions from the position signals and stores this data in RAM (random access memory)  58  by way of latch  60 . RAM  58  can store up to eight hours of position data for later analysis. Upon completion of data gathering, the position data can then be transferred to personal computer  60  by way of RS232 serial interface  62 . Specifically, plug  46  from sensors  12 - 16  is removed from connector  48  and replaced by a conventional serial plug (not shown) from PC  60  using pins  8 - 10  of connector  48 . In the preferred embodiment, controller  20  is attached to carrier  18  using hook-and-eye fasteners. This allows controller  20  to be removed easily for connection to PC  60 . 
     PC  60  is preferably a conventional personal computer such as a PENTIUM-based microcomputer using WINDOWS 95 operating system. The microfiche appendix, included as part of the disclosure hereof, illustrates the preferred program written in Visual Basic for analyzing the position data gathered by controller  20 . The data can be displayed as a chart (deviation over time), a histogram (amount of time per quartile deviation), and a report in terms of a statistical analysis of the mean, average, and standard deviation. These analyses can be saved to disk or printed as is conventional. 
     The program is also operable to animate a hand moving in three dimensions on the screen. The hand can be viewed in real time, slow motion or frame by frame. The preferred animation technique uses screen display data representing about 2300 hand positions stored in mass storage. For position data indicating a given position of the subject&#39;s hand, the corresponding screen display data is retrieved to present a frame. This simple technique enables efficient presentation of the animation. 
     The present invention can also be used in a preventive mode. In this mode, user loads predetermined limits of position movement into RAM  58 . The program operates microcontroller  50  to monitor the positions of the subject&#39;s hand as indicated by sensors  12 - 16 . If the position of the hand reaches one of the indicated limits, beeper  54  is activated thereby providing an audible indication to the subject that a predetermined limit has been reached. By proper setting of these limits, the subject can be trained to avoid those extremes of positions that might lead to injury. 
     Those skilled in the art will appreciate that the present invention encompasses many variations in the preferred embodiment described herein. For example, the invention finds utility in monitoring the movement of other parts of the subject&#39;s body such as head and neck, the torso and back, and legs. Also, the utility is not limited to a human subject but could also include mechanical devices such as robots and the like. In addition, the invention encompasses sensors other than the preferred Hall effect that can monitor position or movement. Moreover, the controller can use other types of devices such as digital signal processors and the like. Having thus described the preferred embodiment of the present invention, the following is claimed as new and desired to be secured by Letters Patent: