  This paper presents the development of an upper limb end-effector based
rehabilitation device for stroke patients, offering assistance or resistance
along any 2-dimensional trajectory during physical therapy. It employs a
non-backdrivable ball-screw-driven mechanism for enhanced control accuracy. The
control system features three novel algorithms: First, the Implicit Euler
velocity control algorithm (IEVC) highlighted for its state-of-the-art
accuracy, stability, efficiency and generalizability in motion restriction
control. Second, an Admittance Virtual Dynamics simulation algorithm that
achieves a smooth and natural human interaction with the non-backdrivable
end-effector. Third, a generalized impedance force calculation algorithm
allowing efficient impedance control on any trajectory or area boundary.
Experimental validation demonstrated the system's effectiveness in accurate
end-effector position control across various trajectories and configurations.
The proposed upper limb end-effector-based rehabilitation device, with its high
performance and adaptability, holds significant promise for extensive clinical
application, potentially improving rehabilitation outcomes for stroke patients.
