Design Of The Synchronous Rotary And Translational Mechanism Using Mecanum Wheel

The synchronous realization of cylindrical workpiece’s high-precision rotation and linear movement is a difficult point in industrial fields.At present,numerous industrial applications utilize spiral feed,worm and screw nut to achieve the synchronous rotation and linear movement of cylindrical workpieces,which has drawbacks such as low work efficiency,poor control accuracy,serious abrasion and so on.A novel rotary and translational mechanism using Mecanum wheels is proposed to overcome the drawbacks of the traditional methods,which can also change speed ratio between linear movement and rotation.This paper mainly studies the geometric model,kinematic characteristics,dynamic model and motion control method of the mechanism.The rotary and translational mechanism using the Mecanum wheel has two structural layouts,which are the ‘wheel-workpiece’s parallel axis’ type and the ‘wheel-workpiece’s orthogonal axis’ type.By analyzing the contact conditions of the Mecanum wheels under the two layouts,the geometrical model of the improved Mecanum wheel under the ‘orthogonal layout’ is established using a novel geometric solution method.In addition,both the design parameter selection method of the improved Mecanum wheel and the improved method of the rollers’ layout are given.The analysis of the motion characteristics of the rotary and translational mechanism is primarily divided into four parts.The motion equations of the left-handed and righthanded Mecanum wheels of the mechanism are derived through the space vector solution method,and then the inverse kinematic model of the mechanism is established.In addition,the forward kinematics model of rotary and translational mechanism is derived by using Moore-Penrose generalized inverse method.Besides,referring to the motion patterns of the omnidirectional mobile platform,the DOFs of the rotary feed mechanism are calculated and the motion patterns that can be achieved by the cylindrical workpiece are analyzed.A virtual prototype is built with reference to the structural plan,and the kinematics simulation of the model is carried out using ADAMS,which verifies the correctness of the kinematics model of the rotary feed mechanism.For the dynamics of the rotary and translational mechanism,based on the NewtonEuler equation,the force between the Mecanum wheel of mechanism and the cylindrical workpiece is analyzed under load.And the dynamic equation of the cylindrical workpiece in the form of Newton Euler is derived.Based on the kinematics model and the overall dynamics model of the rotary and translational mechanism,a set of multi-motor deviation coupling control algorithm based on fuzzy PID speed compensator is designed for the mechanism.This algorithm uses incremental PID for each Mecanum wheel to control,but the speed deviation signal affects the speed adjustment of each Mecanum wheel.The fuzzy PID control is used as the internal algorithm of the speed compensator to effectively reduce the motor synchronization error to achieve synchronous control of the 4 Mecanum wheels of the rotary and translational mechanism.