Design and Motion Control of a Spherical robot with Stereovision

Despite of many works being conducted on spherical robots in recent years, there are few practical applications. Existing spherical robots still have many drawbacks, such as weak capability of environmental perception and low precision of motion control. This paper presents a spherical robot carrying a binocular stereovision, referred to as Visionbot. The robot aims to use stereovision to enhance the environmental perception of spherical robots, thus reducing cumulative errors caused by sliding, mechanical clearance and model error. The mechanical structure of Visionbot is introduced. Under reasonable assumptions, simplified dynamic model is developed by using constrained general Lagrangian formulation. Then, we can decouple linear and steering motions of the robot by linearization. A motion control system with visual feedback for Visionbot is proposed. Effects of the mass of pendulum and time delay caused by visual feedback on motion control of Visionbot are studied by simulations. Simulation results validate the feasibility of the system design. The work presented here is a step towards the overall goal of an autonomous spherical robot.