Design and experimental validation of a simple controller for a multi-segment magnetic crawler robot

Abstract

A novel, multi-segmented magnetic crawler robot has been designed for ship hull inspection. In its simplest version, passive linkages that provide two degrees of relative motion connect front and rear driving modules, so the robot can twist and turn. This permits its navigation over surface discontinuities while maintaining its adhesion to the hull. During operation, the magnetic crawler receives forward and turning velocity commands from either a tele-operator or high-level, autonomous control computer. A low-level, embedded microcomputer handles the commands to the driving motors.This paper presents the development of a simple, low-level, leader-follower controller that permits the rear module to follow the front module. The kinematics and dynamics of the two-module magnetic crawler robot are described. The robot's geometry, kinematic constraints and the user-commanded velocities are used to calculate the desired instantaneous center of rotation and the corresponding central-linkage angle necessary for the back module to follow the front module when turning. The commands to the rear driving motors are determined by applying PID control on the error between the desired and measured linkage angle position. The controller is designed and tested using Matlab Simulink. It is then implemented and tested on an early two-module magnetic crawler prototype robot. Results of the simulations and experimental validation of the controller design are presented.

Integrated Inspection Robotic System for Spherical Tanks: Design, Analysis and Application

“…Permanent magnet adsorption is used for metal walls, which can provide a large adsorption force and does not require external energy consumption. Many types of magnetic wall-climbing robots have been designed and applied, such as magnetic crawler robots [13][14][15][16], climbing robots with magnet-wheeled motion [17][18][19][20][21], omnidirectional climbing robots [22][23][24]. Wall-climbing robots with magnetic adsorption are widely used in the inspection of storage tanks, bridges, and ships.…”

Support and Positioning Mechanism of a Detection Robot inside a Spherical Tank

“…There are many forms of permanent magnet wallclimbing robots, such as magnetic-wheels climbing robots [20][21][22][23], crawler climbing robots [24][25][26][27], and omnidirectional-wheels climbing robots [28][29][30][31]. Wallclimbing robots by permanent magnet adsorption can be effectively used in bridges and ships for inspection operations.…”