Modeling and Control of Opticruise - a Pneumatic Force Actuator

Sammanfattning: Opticruise is an automated transmission system for manual gear boxes. The length stroke is a part of the Opticruise system, in which the mechanical gear shifting process is performed by pneumatic actuators. To reduce piston velocity before the cylinder walls are reached, an oil damper is attached to the pneumatic actuator. The purpose of this thesis is to evaluate if the oil damper can be replaced by a pneumatic feedback control law, a model predictive control scheme or an alternative mechanical construction; in the interest of cost reduction, robustness, shift comfort and shift time. To be able to do a systematic analysis, a mathematical model of the length stroke is developed. The model, developed using a length stroke that is not mounted on a truck, captures the essential dynamics of the system and is used to evaluate control strategies and investigate system properties. As the delay in feedback information from the different sensors is larger than the process time constant, a pneumatic feedback control law is discarded. A model predictive control law is found difficult to realize since the system properties, when the length stroke is placed on a truck, are different in every gearshift. Instead a mechanical construction proposing smaller final chamber volumes is discussed. This solution turns out to be a cost-effective way to achieve a good velocity reduction before the end position. Since feedback control is still an interesting option for future gear shifting systems, the requirements on sensors, controllers and actuators for achieving good controller performance is briefly discussed.