developed a 2-DOF shoulder position transducer employing a load cell to sense shoulder motion of patients with quadriplegia in controlling powered wheelchairs .
We developed a 2-DOF shoulder position transducer that translates shoulder protraction-retraction and elevation-depression into signals that can be used to control the powered humerus of advanced upper-limb prostheses that are currently under development, while at the same time providing proprioceptive and tactile feedback to the shoulder.
We developed three prototype 2-DOF prosthetic shoulder controllers, along with a method to evaluate and compare their performance using position and velocity control schemes.
The framework of the Transverse Assembly is composed of a U-shaped structure that surrounds the hand and forearm and functions as a 2-DOF wrist gimbal, where one of the two axes is aligned with the longitudinal axis of the forearm, component 8 in Figure 2(a), allowing pronosupination.
Recall that joint locks A, B, and C represent 2-, 1-, and 2-DOF joints, respectively, so configuration BC produces a system having five links, five joints, and eight axes of motion yielding a system workspace of F = 6(5 - 5 - 1) + 8 = 2 DOFs.
In this mode, a subject can perform 2-DOF motions of the wrist, where the first DOF is always supination/pronation of the forearm (Figure 6(b) and 6(c)) and the second DOF depends on the orientation of the handle.
As illustrated in Figure 8, the prescribed motion of the added handle in Lift 1 mode, lock configuration BC (Figure 8(a)), is constrained to a 2-DOF spherical surface, the radius of which is defined by the distance from the handle to the transverse axis of the wrist (Figure 8(b)).