Ride Height Control of Trucks with Electrically Controlled Air Suspension Based on PID/PWM Algorithm

Abstract

The truck with Electrically Controlled Air Suspension(ECAS) could reduce the loss of goods by setting running height when transporting, and to enhance the loading &unloading efficiency, a height modulating model was built by combining the theories of thermodynamics of variable-mass charging-discharging system and the vehicle kinetics. To solve such problems as “over-charging”, “over-discharging” and surging, a height control strategy of variable integral PID/PWM was proposed and its controller was developed base on the Freescale single chip. Finally the semi-physical rig was built for simulating the truck with the height controller, and the testing results show that the designed control system satisfies the requirement of height modulation.

Design of a vehicle height and body posture adjustment hybrid automaton of electronically controlled air suspension

“…However, in the previous studies, the continuous variables of the air mass flow rates were usually used as the controller outputs, instead of the SV on–off statuses. In another way, the controller converted the air mass flow rates into the duty cycle of the SV on–off statuses through pulse width modulation (PWM) unit according to the pre‐designed control logic, so as to realize the direct control of the SV, which reduced the control accuracy to a certain extent 11 . Therefore, when the air suspension control system is designed, the direct control of the SV is unable to be realized, and the SV frequent switching will occur by using the PWM control, thereby reducing its operating lifespan.…”

“…In another way, the controller converted the air mass flow rates into the duty cycle of the SV on-off statuses through pulse width modulation (PWM) unit according to the pre-designed control logic, so as to realize the direct control of the SV, which reduced the control accuracy to a certain extent. 11 Therefore, when the air suspension control system is designed, the direct control of the SV is unable to be realized, and the SV frequent switching will occur by using the PWM control, thereby reducing its operating lifespan. Moreover, there are logical relationships among the control variables of charging SV, discharging SV and four air spring SVs that installed in the full-car ECAS, which is difficult to realize the logical control using traditional strategies.…”

Vehicle Height Control of Automotive Air Suspension System Using Fuzzy Neural Network Approach

“…Automotive air suspension system is widely used currently for its outstanding performance in active regulation of suspension stiffness, damping and vehicle height, which will become an important future development direction of the vehicle suspension system [1,2]. Vehicle height adjustment is one of the advantages of air suspension system.…”