Design and control of a steerable screw in-pipe inspection robot

Abstract

An in-pipe inspection robot is designed in this paper for which its pitch rate is controllable and an optimal control is implemented for it subject to input minimization. In-pipe inspection robots are requisite mobile robots to investigate the pipelines. Most of the in-pipe inspection robots are supposed to move with constant pitch of rate. An in-pipe inspection robot is proposed in this paper based on screw locomotion which is steerable in order to handle the pitch rate of the movement and bypass the probable obstacles. Considering the fact that for this robot the number of actuators of the system is more than the Degrees of Freedom (DOFs) of the system, optimization of its control inputs is performed using optimal control approach. In this paper the dynamic model of the mentioned steerable screw in-pipe inspection robot is extracted and it is controlled within a predefined trajectory in an optimal way. The proper mechanism is designed and its related kinematics and kinetics are derived. Then the objective function is defined to optimize the controlling input error simultaneously. The nonlinear state space is linearized around its operating point and optimization is implemented using Linear Quadratic Regulator (LQR). Validity and efficiency of the designed robot and controller are verified using MATLAB simulations.