The driven suspension, that is, the traditional suspension, consists of springs, shock absorbers (shock absorbers) and guiding mechanisms. Its function is to reduce the impact force transmitted from the road surface to the car body and the vibration of the bearing system caused by the impact force. Among them, the spring mainly plays the role of slowing down the impact force, and the main role of the shock absorber is to attenuate the vibration. Because this kind of suspension is driven by external force, it is called driven suspension.
In the control link of active suspension, a device that can produce twitch is installed, and the force suppression method is used to suppress the impact of road surface on the car body and the tilting force of the car body. This kind of suspension is called active suspension because it can generate force by itself.
Active suspension is a new type of suspension controlled by computer developed in recent ten years, which has three conditions: (1) having a power source that can generate force; (2) The actuator can transmit this force and can work continuously; (3) There are many kinds of sensors, and the related data are concentrated on the microcomputer for operation, and the control mode is determined. Therefore, active suspension is a complex high-tech device, which combines mechanical and electronic technical knowledge.
For example, the center of the suspension system of Citroen Sandia, which is equipped with active suspension, is a microcomputer. There are five kinds of sensors on the suspension, which transmit data such as vehicle speed, front wheel braking pressure, the speed of stepping on the accelerator pedal, the amplitude and frequency of the vertical direction of the car body, steering wheel angle and steering speed to the microcomputer. The computer continuously receives these data and compares them with the preset critical value to select the corresponding pause state. At the same time, the microcomputer independently controls the actuator on each wheel, and twitches by controlling the change of oil pressure in the shock absorber, so that the suspension movement that meets the requirements can be generated on any wheel at any time and anywhere. Therefore, Sandia Bridge cars are equipped with a variety of driving modes. As long as the driver pulls the "normal" or "sports" button on the auxiliary instrument panel, the car will be automatically set in the best suspension state to obtain the best comfort performance.
In addition, the active suspension also has the function of controlling the movement of the car body. When the inertia of the car when braking or turning deforms the spring, the active suspension will produce a force opposite to the inertia, reducing the change of the body position. For example, when the car turns, the suspension sensor will immediately detect the inclination and lateral acceleration of the car body. According to the information of the sensor, the computer will compare and calculate with the preset critical value, and immediately decide where and how much load to add to the suspension to minimize the inclination of the car body.