Active suspension systems can be divided into four categories according to whether they contain power sources: full active suspension (active active suspension), slow active suspension system (partial active suspension), semi-active suspension (passive active suspension) and energy fed active suspension.
Fully Active Suspension
Fully active suspension, also known as broadband active suspension, timely adjusts the stiffness and damping of the suspension according to the vehicle movement and road conditions to make it in the best damping state. The fully active suspension can give consideration to the ride comfort and handling stability of the vehicle in the full frequency range of body vibration; It can control the body height in real time and improve the trafficability; It can reduce wheel load fluctuation, improve adhesion, improve handling, and reduce tire wear. However, the disadvantages of fully active suspension are complex structure and control, high hardware requirements, high energy consumption and high cost. These disadvantages limit the popularization and application of fully active suspension in vehicles.
Slow active suspension
Slow active suspension is also called limited bandwidth active suspension. Its actuator only works in a narrow-band frequency range, so it reduces the cost and complexity of the system and is cheaper than full active suspension. Nevertheless, its active control still covers the main body vibration, including the required frequency range of longitudinal, pitch, roll and steering control. It improves the driving performance near the body resonance frequency and improves the control of body attitude. The performance can be very close to the full active system.
Semi active suspension refers to a suspension in which the stiffness of the elastic element of the suspension and the damping coefficient of the shock absorber can be adjusted and controlled according to the needs. Because the spring stiffness is relatively difficult to adjust, the general semi-active suspension does not consider changing the stiffness of the suspension, but only the damping of the suspension. According to the damping level, semi-active suspension can be divided into two types: stage type and stepless type. Semi active suspension is composed of no power source and only controllable damping elements. Because the semi-active suspension has simple structure, hardly consumes vehicle power during operation, and can also obtain the performance close to that of full-active suspension, it has a good application prospect.
Energy fed active suspension
Energy fed active suspension is a kind of active suspension which integrates energy feeding and damping functions. The suspension is equipped with an energy recovery device, which can convert the vibration energy consumed by the shock absorber between the suspensions into energy that can be used by other energy consuming parts of the vehicle, while maintaining good driving smoothness of the vehicle. The realization of energy fed suspension can be divided into mechanical energy feeding and electromagnetic energy feeding. The most important feature of energy fed active suspension is that it can collect and convert the energy of vehicle vibration into the energy that can be used by other components, which is conducive to vehicle energy conservation and is very in line with the requirements of the current era for vehicle energy conservation and environmental protection.