This paper presents analysis and control of a wheeled robot that can move spirally inside the pipeline. The wheeled robot onsidered is composed of two mechanical bodies, a pair of differential-drive wheels, a lifting motor and a steering wheel. The echatronic design allows the robot to easily press against the inner wall and spiral along pipelines of arbitrary inclination angles. Kinematic analysis shows how the lead angle of the differential drive wheels and the steering angle should be coordinated so as to achieve stable spiraling. Steady-state force analysis further gives an analytic expression for the threshold torque needed for supporting the robot at different inclination angles. To ensure successful operation of the robot, four control systems which espectively regulate the spiraling speed, the lifting torque, the steering angle and the lead angle are devised. Particularly for the ead angle control, it is theoretically proved that the feedback measurement can be obtained by performing algebraic operation on signals from a multi-axis gyro. A prototype robot is constructed and is controlled based on the analysis results. Experiments are conducted to verify the robot’s performance on moving spirally in pipelines of different inclination angles.
