Trajectory generation for immediate path-accurate jerk-limited stopping of industrial robots

Stopping the motion of industrial robots in response to warnings or unexpected sensor data is a special case of trajectory generation. In contrast to emergency stops, here the robot has to satisfy the limits of the acceleration and the jerk. In addition, during the deceleration the robot must follow the path accurately, i.e., the shape of the original path may not be left. This is usually done by scaling the desired velocity. However, for curved paths, e.g. those generated by blending of linear motion commands, by sensor corrections, or directly by splines, this method may leave the desired path. The problem is solved by interpolation using the arc length. In contrast to other methods, here the constraints are considered directly, resulting in a time-efficient computation. Finally, the proposed method prevents a rebound caused by the jerk limits when reaching zero velocity. Experiments are presented using a stiff KUKA robot whose path is exactly tracked during deceleration.