Development of an electronic control system for active suspension

The Toyota active control suspension is the first system for passenger cars that actively controls suspension by means of a hydropneumatic system. The authors describe the electronic control unit (ECU), which executes high-speed and highly-accurate processing, and the high-resolution sensors developed for the Toyota Celica´s active control suspension. The ECU has two custom C-MOS 8-b single-chip microcomputers (main-CPU and sub-CPU). The main-CPU primarily processes basic control operations, while the sub-CPU processes input and output signals. The acceleration (G) sensor with amorphous-metal-thin-film distortion gauges detects both longitudinal and lateral acceleration of the vehicle. There are two kinds of height sensors, contact-free magnetic angle sensors with a Hall element and magnetoresistive elements for detecting the suspension stroke of each wheel. There are also two types of pressure sensors, those that have a silicon piezoresistive gauge and those that have an amorphous-metal-thin-film distortion gauge, for detecting the cylinder and system pressure