Variable resistance hand rehabilitation device with linear smart fluid damper and dynometer capabilities

Abstract

A variable resistance hand rehabilitation device and corresponding system. Improvements over the prior art include: a new damping system or damper design, to reduce friction and increase maximum force output; a dynometer feature that enables converting the dynamic device to a static grip force measuring device; a closed-loop controller; and a new graphic user interface for the medical practitioner and new virtual reality game software that allow accurate and smooth operation of the device and increased patient motivation.

1 . A variable resistance hand rehabilitation device adapted to provide a controllable velocity or a controllable resistive force during exercises of a mammalian extremity, the device comprising:
 a support structure for providing strength and structure to the device;   a handle portion moveable in a single degree of freedom and by which the extremity performs the exercises;   a controllable damping system that is structured and arranged to provide a selectively controlled resistance to the extremity using an electro-rheological fluid having a resistivity that is continuously variable throughout a stroke cycle; and   at least one sensing device, each of which is mechanically coupled to the handle portion and each of which is adapted to provide measurement data for controlling the resistivity of the electro-rheological fluid.   
   
   
       2 . The device as recited in  claim 1 , wherein the handle portion includes a first, movable handle portion and a second, fixed handle portion, the first, movable hand portion having a single degree of freedom of movement in the direction of the fixed handle portion. 
   
   
       3 . The device as recited in  claim 2 , wherein the at least one sensing devices includes at least one of:
 a linear potentiometer that is mechanically coupled to the movable handle portion and adapted to measure linear displacement of the handle portion during a stroke cycle; and   a linear force sensing device that is mechanically coupled to said movable handle portion and adapted to measure a force or pressure applied by a mammalian extremity throughout the stroke cycle.   
   
   
       4 . The device as recited in  claim 1  further comprising at least one of:
 a locking mechanism that is adapted to lock the shaft in a fixed position so that the device provides static rather than dynamic data; and   a handle return force control system that is adapted to return the handle portion to a starting point of the stroke elastically.   
   
   
       5 . The device as recited in  claim 4 , wherein the handle return force control system is structured and arranged to return the handle portion to a start position of the stroke after completion of the stroke cycle, the handle return system comprising:
 a pair of notched scales having a plurality of positioning notches, each of the pair being disposed at a distal end of the support structure;   a pair of slidable mounts, each of the pair being slidably disposed on one of the pair of notched scales and being structured and arranged to be fixedly attachable at a desired, discrete positioning notch on the corresponding notched scale; and   a pair of elongate members, each of the pair being fixedly attached to one of the pair of slidable mounts at a first end and to one of the at least one sensing device at a second end.   
   
   
       6 . The device as recited in  claim 1 , wherein the controllable damping system includes:
 at least one electrode that is structured and arranged as coaxial, concentric cylinder, a gap for the transmission of the electro-rheological fluid being formed between adjacent electrodes or between a single electrode and another surface in the damping system; and   a protective damper case, the case including:
 a center damper case having an inner bore that is adapted to provide a tight interference fit with an outermost electrode of said at least one electrode; 
 a case manifold that is releasably attachable to one end of the center damper case; and 
 a case end cover that is releasably attachable to another, opposite end of the center damper case. 
   
   
   
       7 . The device as recited in  claim 6 , wherein the center damper case is precision manufactured of polyoxymethylene. 
   
   
       8 . The device as recited in  claim 6 , wherein the case manifold includes at least one of:
 at least one electrode alignment tab, each of said alignment tab having a thickness that is equal to the gap distance; and   a plurality of electrode alignment pin holes that are structured and arranged to be in registration with a corresponding plurality of alignment pin holes that are disposed on each end of each of the plurality of electrodes; and   a gland that is adapted for holding a sealing device.   
   
   
       9 . The device as recited in  claim 8 , the sealing device being selected from a group comprising: an o-ring and a spring seal. 
   
   
       10 . The device as recited in  claim 6 , wherein the case end cover includes at least one of:
 at least one electrode alignment tab, each of said alignment tab having a thickness that is equal to the gap distance;   a plurality of electrical connection holes that are adapted to receive an electrical connection device;   at least one air trap, each of the at least one air trap being fluidly coupled to a corresponding slide valve;   a plurality of electrode alignment pin holes that are structured and arranged to be in registration with a corresponding plurality of alignment pin holes that are disposed on each end of each of the plurality of electrodes; and   a screw cap for sealing a top of a volume compression chamber.   
   
   
       11 . The device as recited in  claim 6 , wherein the case end cover includes a volume compression chamber that is filled with a closed-cell foam. 
   
   
       12 . The device as recited in  claim 1 , further comprising a controller for controlling the controllable damping system and for receiving measurement data from the at last one sensing device, the controller structured and arranged to vary a magnitude of voltage delivered to an electrode that is electrically coupled to the damping system or a duration of voltage delivery, said voltage being adapted to tune the resistivity of the electro-rheological fluid, to provide a desired isokinetic or isotonic response. 
   
   
       13 . The device as recited in  claim 1 , wherein the at least one electrode includes an central bore electrode, a middle electrode, and an outer electrode. 
   
   
       14 . The device as recited in  claim 13 , wherein the central bore electrode has a negative polarity, the middle electrode has a positive polarity, and the outer electrode has a negative polarity. 
   
   
       15 . The device as recited in  claim 13 , wherein each of said at least one electrode has a height and the height of the middle electrode is less than the height of the central bore and outer electrodes. 
   
   
       16 . The device as recited in  claim 15 , wherein a spacer is provided for fine tuning the damping system. 
   
   
       17 . The device as recited in  claim 11 , wherein the closed-cell foam is buna-based or a neoprene-based closed-cell foam. 
   
   
       18 . The device as recited in  claim 12 , wherein the controller is adapted to provide an isotonic or isokinetic motion to the movable handle portion. 
   
   
       19 . The device as recited in  claim 12 , wherein the controller is adapted to account for any Stribeck effect. 
   
   
       20 . The device as recited in  claim 1 , the at least one electrode being a single electrode and the damping system further comprising a choke assembly having a through hole through which the electro-rheological fluid is forced from the damping chamber to a volume compression chamber and vice versa. 
   
   
       21 . The device as recited in  claim 1 , the device having a rolling diaphragm seal to provide a rolling seal. 
   
   
       22 . The device as recited in  claim 1  further comprising a second, spring-biased piston that is structured and arranged to act in an opposite direction as the damping piston. 
   
   
       23 . The device as recited in  claim 21 , wherein an electro-rheological fluid valve is disposed between the damping piston and the spring-biased piston. 
   
   
       24 . The device as recited in  claim 23 , wherein the electro-rheological fluid valve includes plural positive polarity members and plural negative polarity members. 
   
   
       25 . A rotary damping system for providing a braking action using an electro-rheological fluid, the system comprising:
 a body having a first, upper portion and a second, lower portion made from an electrically non-conductive material;   a first plurality of positive polarity electrodes having a variable first gap distance between adjacent negative polarity electrodes;   a second plurality of negative polarity electrodes having a variable second gap distance between adjacent positive polarity electrodes;   the upper portion of the body structured and arranged to accommodate the first plurality, which are rotatable, and the lower portion of the body structured and arranged to accommodate the second plurality, which are stationary,   the first plurality being disposed within the gap between adjacent negative polarity electrodes, and   the second plurality being disposed within the gap between adjacent positive polarity electrodes; and   a safe high voltage connection that is electrically coupled to a voltage source and to the plurality of first plurality of positive polarity electrodes.   
   
   
       26 . The system as recited in  claim 25 , wherein each of the first plurality of positive polarity electrodes are substantially hollow cylinders that are coaxial and concentric to one another. 
   
   
       27 . The system as recited in  claim 25 , wherein each of the second plurality of negative polarity electrodes are substantially hollow cylinders that are coaxial and concentric to one another. 
   
   
       28 . The system as recited in  claim 25 , wherein each of the first and second pluralities of electrodes has a height, and the height of the first plurality differs from the height of the second plurality. 
   
   
       29 . The system as recited in  claim 25  further comprising an electrically-conductive, elongate body that is mechanically coupled to the first plurality of positive polarity electrodes. 
   
   
       30 . The system as recited in  claim 25  further comprising a controller for selectively controlling a voltage delivered to the first plurality of positive polarity electrodes, to activate the electro-rheological fluid between adjacent positive and negative polarity electrodes to cause the system to brake. 
   
   
       31 . A system for providing a controllable velocity or resistive force during exercises of a mammalian extremity, the system comprising:
 variable resistance hand rehabilitation device including:
 a support structure for providing strength and structure to the device; 
 a handle portion by which the extremity performs the exercises through translating in a single degree of freedom; 
 a controllable damping system that is structured and arranged to provide a selectively controlled resistance to the extremity using an electro-rheological fluid having a resistivity that is continuously variable throughout a stroke cycle; 
 at least one sensing device, each of which is mechanically coupled to the handle portion and each of which is adapted to provide measurement data for controlling the resistivity of the electro-rheological fluid; and 
 a controller for controlling the controllable damping system and for receiving measurement data from the at last one sensing device, the controller structured and arranged to vary current flow to an electrode that is electrically coupled to the damping system, said current being adapted to tune the resistivity of the electro-rheological fluid, to provide a desired isokinetic or isotonic response.