Dual Control for Jerk-Driven Robotics in Rehabilitative Planar Applications.

Francesco Aggogeri,Cinzia Amici,Nicola Pellegrini

doi:10.3390/mi11020141

Abstract

This study compares a set of strategies to plan and control the trajectory of a robotic device in a planar workspace. These strategies are based on an affective application of jerk-laws able to indicate undesirable conditions (e.g., vibrations) facilitating the device control. The jerk is the time derivative of acceleration, and this solution provides an indirect means to control the variation rate of the actuator torques, while avoiding the complex robot dynamic models and their algorithms for computing the dynamics. In order to obtain a smooth trajectory, a regulator to control a robotic device has been developed and validated. It consists of the implementation of two control modules able to (i) generate the predefined trajectory and (ii) guarantee the path tracking, reducing unwanted effects. In this case a simple S-shaped path has been originated by the “trajectory generator module” as a reference movement to rehabilitate upper limb functionality. The numerical simulation and the results of preliminary tests show the efficacy of the proposed approach through the vibration smoothness appraisal associated with the motion profile.

Highlights

The application of robotics in progressing assistive and rehabilitative movement function recovery has gained significant momentum in recent years
This study compares a set of strategies to plan and control the trajectory of a robotic device in a planar workspace
This study proposes a set of strategies to control the therapy trajectory of a Cartesian mechanism in a planar workspace

Summary

Introduction

The application of robotics in progressing assistive and rehabilitative movement function recovery has gained significant momentum in recent years. The novelties of the contribution are: (i) the application of well-known industrial robotic concepts in rehabilitative application; (ii) the dual-control development is based on the trajectory generator module that imposes the requested path (S-shape, cycloidal, trapezoidal, etc); (iii) user-safety is guaranteed from a performance index for misusage, the jerk-based index is hesitation-sensitive for non-expert subjects; (iv) the solution provides the indirect means to control the variation rate of the actuator torques, avoiding the complex robot dynamic models and their algorithms for computing the dynamics; and (v) the invariance from dominating modal frequencies could be an opportunity to propose a flexible, light, and wearable device that patients could use at home.

Rehabilitation Requirements and Research Opportunities

Problem Statement