Smooth Motion Control Policy of Wall-Pressing Pipeline Robots

Aiming at several key problems, such as motion discontinuity, getting stuck and body deformation, and appearing in the motion of wall-pressing pipeline robots (WPPRs) controlled by the differential drive principle, in this article, a smooth motion control policy (SMCP) is proposed. To improve the generality of the SMCP, the relationship between the walking unit driving motor load and the relative attitude of the WPPR is analyzed, and a real-time relative attitude estimation method that only relies on the walking unit driving motor current is proposed. In addition, the WPPR attitude change law when the velocity transmitted to the robot body is not satisfied with the differential drive mode is obtained. Finally, an SMCP based on a PID controller whose feedback signal is the difference between the actual and ideal attitudes of the WPPR is built to reduce the influence of friction fluctuation for the motion. To verify the SMCP, a new WPPR is designed, and a comparative experiment is performed to verify the effect of the SMCP. The experimental results show that the variance of the walking unit driving motor currents is smaller, and the velocity of the robot is larger when the robot adopts the SMCP. Thus, the proposed method can make the WPPR move more smoothly.