Cascaded LQ and Field-Oriented Control of a Mobile Inverse Pendulum (Segway) with Permanent Magnet Synchronous Machines

Abstract

This paper presents the development and implementation of a two-wheeled mobile robot that balances stably and precisely. The sensor system consists of 3 gyroscopes, 3 acceleration sensors and 2 incremental encoders. In contrast to most realizations, the drive train (actuator system) consists of two permanent magnet synchronous machines with attached planetary gears and rubber wheels. Each machine is individually torque controlled by means of a field-oriented control system. This drive system guarantees the direct, wear-free and stepless linear conversion of a torque demand by the higher-level control loop. The robot itself is modelled using a LQ-controlled state-space model with attached position setpoint input. Matlab/Simulink and Simscape are used to determine the control parameters and to program the microcontrollers. Measurement results with various parameters complete the picture.