Abstract <p>Efficient and flexible autonomous obstacle avoidance motion capabilities have become an urgent and practical requirement for robots in the current production life. Aiming at the problem that the joint vibration caused by excessive impact affects the quality of work when the robotic arm is operating, an optimal spraying trajectory planning method for the robotic arm is proposed. In this paper, we take the four-degree-of-freedom robotic arm as the research object, use five times nonuniform B spline functions to construct the trajectory of the robotic arm, construct the multiobjective optimization function of time and impact, optimize the trajectory based on the multiobjective particle swarm optimization algorithm, and then get the required solution from the Pareto front-end through the normalization of the objective weighting function. Real robots are used for experimental verification, and the improved multiobjective optimization particle swarm algorithm, PAD-MOPSO is used to achieve the effect of multiobjective optimization of time and impact, and the displacement, velocity, acceleration, and torque during the motion process are within the constraint range.</p>