To reduce the effects of collision between the robot and environment

it is generally required to limit the maximum torque of each joint while the robot follows the command trajectory. For keeping the Cartesian path unchanged and following quickly under the dynamic constraints of a multi-joint robot

the effects of joint space torque constraints on the velocity and acceleration of Cartesian space are analyzed. The maximum acceleration allowed is analyzed in real time

and the corresponding velocity and position are calculated while the robot keeps the Cartesian path unchanged. The purpose of safe operation is achieved. The method was verified on a self-developed six-degree-of-freedom lightweight manipulator. The result shows that the method can constrain the torque to a set range

the replanned trajectory keeps the Cartesian path unchanged

and the command trajectory is followed quickly.