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.

We present a new interdisciplinary educational program in multifunctional robotics built around three versatile vehicles -a mobile inverted pendulum (BeagleMiP), a four-wheelsteerable rover (BeagleRover), and a quadrotor (BeagleQuad) -all built around the TI BeagleBone Black (BBB), together with a new printed circuit connector board, or "cape", designed specifically for multifunctional robotics applications. The program is coupled with a C library of key robotics functions, together with working example codes and educational materials, making it exceptionally easy to get started, and to extend. Volume 1 of the program targets embedded control & robotics education at the "maker" level, and is easily accessible in high schools and beyond. Building directly on Volume 1, Volume 2 of the program targets the "professional" level, building on knowledge of ODEs, dynamics, control theory, and op amps, and is useful in senior-level college capstone courses & industry. Prototype versions of BeagleMiP were used by the authors during the last three offerings of UCSD's fall-quarter senior-level Embedded Control & Robotics course. The electronics used have evolved from an Arduino Nano and various small development boards, assembledon an 830-point solderless breadboard, to the powerful $50 BBB paired with our highly extensible robotics cape, which incorporates the commonly-needed additional electronics for many robotics applications, including an IMU, barometer, battery management, H-bridges, real-time clock with battery backup, and over a dozen convenient connectors, into a very small footprint. The best-practices programming techniques fostered by this program implement an advanced software architecture written in C, with different threads running at different loop rates and priorities. The resulting educational program will be commercially available soon, marketed in partnership with WowWee Robotics.! 1