A Multithreaded Implementation of Assist Functions to Control a Virtual Reality Model of a 6-DoF Robot Arm for Rehabilitation Applications

This paper describes a multithreaded platform to implement a haptic interface to control a Virtual Reality (VR) model of a 6DoF arm with applications towards rehabilitation robotics. The approach allows the defined threads to execute concurrently, resulting in increased utilization of the processor resources and higher instruction execution rates consistent with a realistic rendering of the touch sensation and smooth graphics transitions for the VR simulation. The haptic interface allows for physical rendering of the human–machine interactions through force feedback and velocity scaling enhancing the manipulation capabilities of persons with disabilities. Assist functions are modeled through the use of physical simulation of springs, spring with damping, and velocity scaling. The level of assistance is calculated by concurrent threads running the virtual model of the arm and the haptic loop at two different update rates.