Design and Implementation of a Delay-Compensated Pneumatic Brake Controller for Heavy Vehicles

Abstract

Heavy Commercial Road Vehicles (HCRVs) are crucial to the effective transfer of products and people in modern transport systems. Economy of a country, as they rely on passenger and freight transportation, is depends highly on the HCRVs. Various Safety systems in the context of safety systems for vehicles, Collision Avoidance System (CAS) as well as Anti-Lock Braking System (ABS) etc., are some systems capable enough in assisting drivers to avoid accidents are of prime focus. However, challenges are there in design of safety systems for HCRVs. Considering pneumatic brake system various factors such as delay, significant variations of mass during different operations such as laden and unladed operation, and during braking the dynamic load transfer and all above factors are challenges faced during active safety system design. Pneumatic brake system is the traditional actuation system for HCRVs. For medium of actuation, compressed air is used. Compressibility of air, pipe length and valve response time are some of the factors that affects its dynamic response. These factors induce a delay in the system causing the stopping distance of vehicle and response time of brake system to increase. This time delay and its effects on the system in-turn affects the overall performance of the system. For the efficient and optimal performance of active safety system is very much dependent on the performance of the pneumatic brake system. Thus, a PID controller is created for a pneumatic brake system to enhance performance. The gains of the PID Controller are optimized using the Grey-Wolf Optimizer. The Padé Approximation is used to estimate the time delay since the system has a time delay. Then PID Controller is designed for this time delay approximate transfer function. Other Methods for delay compensation such as State -Prediction is also used. Controller other than PID such as Sliding Mode Control is also used. Performance of controllers incorporating time delay is compared with other controllers that include state predictors that are compensating for the time delay. Also, different controllers with state predictors are compared for performance evaluation of controllers. Performance of brake controllers is also evaluated by considering ABS operation. Two loop control design is used. Brake controllers will act as inner control loop. The purpose of this work for the controller design for ABS is to increase the braking effort and keep control during an emergency braking scenario. When traveling long distances on HCVRs, driver fatigue could be a risk. ABS adds an extra safety net. ABS is designed to assist the HCVRs in the event that the driver falls asleep.