Robotic upper trunk support device

Abstract

An upper trunk training system may include a connection module including an actuation link configured to be coupled to a user's trunk, an output link coupled to the actuation link, and a base frame configured to be coupled to the user's trunk. An upper trunk training system may include a variable stiffness module including a cam fixed to a cam shaft coupled to the base frame, a cam follower coupled to the base frame and biased toward the cam. An upper trunk training system may include a stiffness control module including a sun gear fixed to the cam shaft, a planetary gear coupled to the output link of the connection module and meshed with the sun gear, a ring gear meshed with the planetary gear, and an electric machine coupled to the ring gear to rotate the ring gear to increase a stiffness of the upper trunk training system.

What is claimed is: 
     
         1 . An upper trunk training system, comprising:
 a connection module including
 an actuation link configured to be coupled to a user's trunk, 
 an output link coupled to the actuation link, and 
 a base frame configured to be coupled to the user's trunk; 
   a variable stiffness module including
 a cam fixed to a cam shaft coupled to the base frame, 
 a cam follower coupled to the base frame and biased toward the cam; and 
   a stiffness control module including
 a sun gear fixed to the cam shaft, 
 a planetary gear coupled to the output link of the connection module and meshed with the sun gear, 
 a ring gear meshed with the planetary gear, and 
 an electric machine coupled to the ring gear to rotate the ring gear to increase a stiffness of the upper trunk training system. 
   
     
     
         2 . The upper trunk training system of  claim 1 , wherein the connection module and the user's trunk form a four-bar linkage with a single degree-of-freedom. 
     
     
         3 . The upper trunk training system of  claim 1 , wherein the cam includes a zero-support region, a force-matching region, a motion-restriction region, and a transition region. 
     
     
         4 . The upper trunk training system of  claim 1 , wherein the cam follower includes a follower roller engaged with the cam. 
     
     
         5 . The upper trunk training system of  claim 1 , wherein the cam follower includes a spring biasing the cam follower toward the cam. 
     
     
         6 . The upper trunk training system of  claim 5 , wherein the spring is adjustable so that the stiffness of the upper trunk training system can be changed. 
     
     
         7 . The upper trunk training system of  claim 1 , wherein the cam follower includes a potentiometer that provides displacement information indicative of a displacement of the cam follower, and
 wherein operation of the electric machine is based on the displacement information.   
     
     
         8 . The upper trunk training system of  claim 1 , wherein the sun gear and the ring gear are coaxial with the cam shaft. 
     
     
         9 . The upper trunk training system of  claim 1 , wherein the planetary gear includes three planetary gears all coupled to the output link. 
     
     
         10 . The upper trunk training system of  claim 1 , wherein the output link is rotatably mounted to the cam shaft. 
     
     
         11 . The upper trunk training system of  claim 1 , wherein the stiffness control module further includes:
 a driven gear rigidly mounted to the ring gear, and   a worm gear coupled to the electric machine and meshed with the driven gear.   
     
     
         12 . The upper trunk training system of  claim 11 , wherein the driven gear is coaxial with the cam shaft. 
     
     
         13 . The upper trunk training system of  claim 1 , wherein the stiffness of the upper trunk training system is defined by the variable stiffness module when the electric machine is not moving, and
 wherein the stiffness of the upper trunk training system is defined by both the variable stiffness module and the stiffness control module when the electric machine is moving.   
     
     
         14 . The upper trunk training system of  claim 1 , wherein the electric machine modulates the stiffness of the upper trunk training system based on a speed of rotation of the electric machine. 
     
     
         15 . The upper trunk training system of  claim 1 , wherein the electric machine is a stepper motor. 
     
     
         16 . An upper trunk training system comprising:
 a four-bar linkage configured to be coupled to a user's trunk;   a cam shaft coupled to the four-bar linkage;   a cam fixed to the cam shaft for rotation therewith;   a cam follower coupled to the four-bar linkage and including a cam roller in contact with the cam;   a spring biasing the cam follower toward the cam;   a sun gear fixed to the cam shaft for rotation therewith;   three planetary gears coupled to the four-bar linkage and meshed with the sun gear;   a ring gear meshed with the three planetary gears; and   a stepper motor coupled to the ring gear to rotate the ring gear to modulate a stiffness of the upper trunk training system.   
     
     
         17 . The upper trunk training system of  claim 16 , wherein the four-bar linkage includes a base from supporting the cam shaft and an output link including a carrier mounted to the three planetary gears. 
     
     
         18 . The upper trunk training system of  claim 16 , further comprising:
 a driven gear coupled to the ring gear; and   a worm gear driven by the stepper motor and meshed with the driven gear.   
     
     
         19 . The upper trunk training system of  claim 16 , wherein the cam includes a zero-support region, a force-matching region, a motion-restriction region, and a transition region. 
     
     
         20 . An upper trunk training system comprising:
 an actuation link configured to be coupled to an upper portion of a user's trunk;   an output link rotatably coupled to the actuation link;   a base frame configured to be coupled to a lower portion of the user's trunk; and   a parallel elastic actuator coupled between the output link and the base frame, the parallel elastic actuator including:
 a cam shaft, 
 a cam fixed to the cam shaft for rotation therewith 
 a cam follower coupled to the base frame and including a cam roller in contact with the cam; 
 a spring biasing the cam follower toward the cam; 
 a sun gear fixed to the cam shaft for rotation therewith; 
 three planetary gears coupled to the output link and meshed with the sun gear; 
 a ring gear meshed with the three planetary gears; and 
 a stepper motor coupled to the ring gear to rotate the ring gear to modulate a stiffness of the upper trunk training system.