Kinematic analysis and simulation of a ball-roller pair for the active-caster robotic drive with a ball transmission

Abstract

In this paper, kinematics analysis and simulation of the ball-roller pair is presented. The authors grope has been developed a special kind of transmission with a dual-ball configuration for transmit drive powers to wheel shaft and steering shaft of an active-caster mechanism (ACROBAT). In the transmission design, two balls are required where one ball is used for combining the two motor powers to rotate the ball in 2D way while another ball is for distributing the combined power to the wheel and steering. The transmission design enables an omnidirectional robot with three active casters to be controlled its 3D motion by three motors with no redundancy. To reduce the number of friction drive between balls and rollers in the first design, we are now planning to build a new type of ACROBAT with a single ball transmission. For this purpose, we analyze a kinematics of a ball-roller pair mechanism and verify the kinematics and motions of proposed mechanism by simulations. From the results, it is confirmed that proposed transmission is applicable for ACROBAT mechanism for realizing the non-redundant omnidirectional motions.