Control of Over-Actuated Systems — From Practical to Theoretical Concepts with Application in Hybrid Powertrain Speed Control Development

With the introduction of newer actuators, such as four-wheel steering or electro-hydraulic brakes, vehicles are becoming more over-actuated. There are two main reasons to use over-actuation in vehicles: improving safety (due to actuator redundancy) and enhancing dynamic performance (handling, comfort, and fuel efficiency). These actuators create new degrees of freedom that cannot directly be utilized to improve vehicle safety and performance; new control system methods are required. In this paper, we study the design of robust control for over-actuated systems. We propose several approaches: a method based on Youla parameterization, one method relying on an $H_{\infty}$-optimization, and one method using properties of the Smith-McMillan form of over-actuated systems. The application of each strategy is illustrated through the design of a speed controller for a hybrid electric diesel engine powertrain equipped with a Crank-Integrated Starter Generator (CISG).