关键词: 独立驱动脚轮式全向移动平台, 模型预测控制, 轨迹跟踪, PID(Proportion Integral Differential), 运动学模型

Abstract: Aiming at the problem that existing motion control strategy cannot guarantee high-precision pose control for independently driven caster-type omnidirectional mobile platform, a double closed-loop trajectory tracking control strategy was proposed, combining Model Predictive Control (MPC) and Proportion Integral Differential (PID) control. Firstly, kinematic geometric relationship was used to establish three-degree-of-freedom kinematics model of independently driven caster-type omnidirectional mobile platform in world coordinate system, and based on orthogonal decomposition method, inverse kinematics model of platform in robot coordinate system was established to reflect relationship between center point speed of platform and rotation speed of each caster. Secondly, MPC was used to design position controller based on three-degree-of-freedom kinematic model, so that platform can track position of desired trajectory, and optimal control quantity was solved through the position controller while taking multi-objective constraints into account. Finally, PID was used to design speed controller to track desired speed output by position controller. Desired wheel speed was calculated through platform inverse kinematics model, thereby driving platform to achieve omnidirectional motion. Effectiveness of proposed control strategy is verified through simulation, and platform can effectively track linear trajectories and circular trajectories. Experimental results show that compared with position single-loop trajectory tracking control strategy that decouples drive wheel speed through angle inverse kinematics model of platform, system overshoot is reduced by 97.25% and response time is shortened by 36.84% after adding speed inner loop.

Key words: independently driven caster-type omnidirectional mobile platform, Model Predictive Control (MPC), trajectory tracking, Proportional Integral Derivative (PID), kinematic model