Braking force control of an electric drum brake system
Abstract
The brake equipment is one of the most important safety equipment for the operation of the vehicle regardless of the types of the power source. In general, a disk brake and a drum brake system are the most widely used braking systems for both passenger and commercial vehicles. The major superiority of the drum brake over the disk brake is the brake factor. To be specific, the drum brake requires less input power to produce the same amount of braking power as compared to the disk brake. Therefore, it is felt that the drum brake might be the future of the braking system for an electric vehicle. Reviewing literatures related to the electric braking system technology found that a few designs of an electric drum brake have already been investigated. However, the electromagnetic trailer brake has been widely used as a common braking system for a trailer truck. Therefore, the adoption of this trailer brake to be used in a passenger vehicle seems to be a good logical starting point for the development of a universal electric drum brake. The main objective of this research is to design the electromagnetic drum brake for a passenger vehicle based on the design and working principle of the already exist electromagnetic trailer brake. To do so, the physical modeling of the electromagnetic trailer brake is developed. The mathematic models for a conventional hydraulic drum brake, which is aimed to be the benchmark for the development of an electric drum brake, is also be developed. Both drum brake models are validated via available data from the literatures. This research also studies the design of a controller suitable for the proposed electric drum brake using wheel slip model predictive control (MPC). The performance of this controller with electric drum brake is compared with the conventional hydraulic controlled drum brak system. The results show that the response time of electric drum brake is higher than hydraulic drum brake around 8 times, while the brake actuation force of the electric drum brake is lower than the hydraulic drum brake around 5 times, when generating the same braking torque magnitude. Also, the electric drum brake uses higher input brake power than the hydraulic drum brake around 13 times. In terms of braking efficiency however, both drum brake system exhibits comparable braking efficiency. Based on the rough feasibility study, the average production price of the electric drum brake could be cheaper than the hydraulic drum brake around 1.7 times from the use of electrical system to generate the actuation force. While the drum brake mechanism of both electric drum brake and hydraulic drum brake are almost identical, there should be some minor changes for the drum brake production to commercially produce the electric drum brake in the future.