关键词: 七自由度装卸货机器人, 参数辨识, 改进摩擦力模型, 优化算法, 激励轨迹

Abstract: The seven-degree-of-freedom ( 7DOF) loading and unloading robot, as a highly flexible special robot is widely used in logistics handling, warehousing automation and other fields. Due to its complex mechanical structure and the requirement for high-precision trajectory tracking, it is essential to model its dynamic characteristics accurately. This establishes the kinematic model of the loading and unloading robot based on the MDH method, constructs the rigid body dynamics equations using the Newton-Euler iterative method, and derives the symbolic expression for joint torques. It analyzes the linearized form of the dynamics equations and the minimum inertia parameter set, proposes the use of finite Fourier series as the excitation trajectory, and designs an optimization objective function. The fmincon function is used to solve for the optimal trajectory parameters. The traditional linear friction model is improved to a sigmoid function model to eliminate the torque jump and chattering issues during joint reversal. Experiments show that the improved friction model significantly reduces the tracking error between theoretical and actual torques, optimizing the joint reversal control performance. This method provides theoretical support for high-precision motion control and energy optimization of loading and unloading robots.

Key words: seven-degree-of-freedom loading and unloading robot, parameter identification, improved friction model, optimization algorithm, excitation trajectory