Stable visual servoing of an overactuated planar parallel robot

This work presents an image-based visual servoing scheme applied to a class of overactuated planar parallel robots with revolute joints. The objective is to move the robot end-effector to a desired constant image position. A Proportional Derivative algorithm computes torques for the robot active joints. The Derivative and Proportional actions operate at the visual level. A linear filter allows obtaining velocity estimates from position measurements from a vision system. Lyapunov Stability theory allows concluding closed loop stability without invoking the LaSalle-Krassovsky invariance principle. Experiments on a laboratory prototype permit evaluating the performance of the closed loop system.