Obstacle Avoidance Trajectory Planning for SCARA Manipulators based on Analytical Kinematics and Improved APF

To address the issues of real-time performance and smoothness in obstacle avoidance trajectory planning for SCARA manipulators within complex industrial environments, a closed-loop planning scheme combining analytical kinematics, an improved Artificial Potential Field (APF) method, and Time-Optimal Trajectory Planning (TOTP) is proposed. Firstly, the forward and inverse kinematic models of the manipulator are established based on the D-H parameter method, utilizing closed-form analytical solutions to enhance spatial mapping efficiency. Secondly, aiming at the defects of traditional APF, such as trapping in local minima and goal unreachability, the repulsive field model is optimized by introducing a distance attenuation factor, and a safe geometric path is generated in Cartesian space combined with an obstacle expansion envelope strategy. On this basis, the TOTP algorithm is utilized to perform joint-space time-parameterization of the geometric path, ensuring the trajectory satisfies velocity and acceleration constraints. Simulation results demonstrate that the trajectory generated by this method is continuous and smooth without step phenomena, and the angular velocities of each joint exhibit a bell-shaped distribution, effectively solving interference problems in complex environments and meeting the requirements of high-intensity industrial assembly.