Modular approach for control design of an autonomous two-wheeled inverted pendulum

Abstract

Modular design of systems is an important tool to subdivide complex problems into smaller parts (sub-systems) that are easier to analyze and design. The scope of this paper is to present a methodology for modularizing the design of a mechatronic system through the adequate decoupling of its main subcomponents. The proposed approach is applied in the design of an automatically guided two-wheeled inverted pendulum that works by following a specified acceleration/velocity profile in a longitudinal trajectory. With this purpose, the approach considers the relations among the different parts of the platform belonging to multiple physical domains such as the mechanical platform and wheels, DC motors, power system drivers, gearboxes and controllers. The control design was derived carefully based on a linearized model using a cascade architecture by appropriately choosing the main variables and the control loop structures. Each compensator transfer function was then designed using Root Locus approach. The complete designed system was simulated such that its response to a previously established sequence of position input commands could be verified. The final simulation behavior of the platform succeeded to reach the proposed maximum speed of 20km/h in less than 30s while following the position trajectory. Results showed that the method is applicable as a tool to facilitate independent design by decoupling the influence of a subpart on another, which also ensures reconfigurability and variety in the design of mechatronic products.