Abstract: In order to study the issue that the tool-changing robot can move smoothly along a specific route， kinematics analysis and trajectory planning of the robot model are carried out. The kinematics model of the robot is derived by using the screw theory combined with Monte Carlo simulation to obtain the distribution of the working space at the end of the robot. A trajectory planning method for multi-node and multiple-curve motion is proposed. The joint displacement， angular velocity and angular acceleration are used as the evaluation indicators， and 3-3-3， 5-5-5 and 4-5-5 spline curves are used to plan the trajectories respectively. The prototype platform test shows that the 4-5-5 mixed polynomial can obtain a relatively stable acceleration curve， which effectively solves the problem of excessive steps and sudden change in acceleration. The research provides a basis for the trajectory planning of complex tool-changing paths of manipulators.

Key words: tool-changing robot; kinematics; trajectory planning; multi-node; hybrid spline curve