The design and testing of an electromagnetic anti-lock brake system with microprocessor control

Anti-lock brake systems are used to prevent wheel lockup on most vehicles sold today. This thesis involves the design and testing of an electromagnetic antilock brake system. This system is designed as a replacement for the current anti-lock brake systems used on drum brakes. The primary difference in the two systems is the replacement of the pressure modulator that is currently used with an electromagnetic release system. The Electromagnetic release system consists of two main parts, a cam and an electromagnet.The cam is located between the lower pivot points of the brake shoes. The cam is connected to the electromagnet by a release arm. The magnet is held in close proximity to a steel plate connected to the rotating hub. When the electromagnet is energized it is attracted to the rotating steel plate. The cam is then rotated by the release arm which is connected to the electromagnet. This causes the lower points of the brake shoes to move together and release the brake, thus preventing complete wheel lockup, and tends to keep the wheel slip near the peak of the braking coefficient curve. When the deceleration has decreased to an acceptable level, the magnet is de-energized and the return spring rotate the cam which reapplies the brake. The electromagnetic release system is less expensive and simpler than the pressure modulators used in current anti-lock drum brake systems.The electromagnetic release system also has the capability to operate faster than the pressure modulators used in current anti-lock brake systems.The electromagnetic anti-lock brake system proved to work reasonably well in preventing wheel lockup and in controlling deceleration. The electromagnetic anti-lock brake system was limited by the capabilities of itk control system. The control system used for testing had a limited resolution and reduced the speed of the system.The electromagnetic anti-lock brake system has the potential for being a suitable replacement for current anti-lock drum brake systems.VI