Abstract
Active seat suspensions can be used to reduce the harmful vertical vibration of a vehicle’s seat by applying an external force using a closed loop controller. Many of the controllers found in the literature are difficult to implement practically, because they are based on using unavailable or difficult and costly measurements. This paper presents both simulation and experimental studies of five novel, simple, and cost-effective control strategies to be used for an active seat suspension in order to improve ride comfort at low frequencies below 20 Hz. These strategies use available and measurable feedforward (preview) information states from the vehicle secondary suspension, as well as feedback states from the seat suspension, together with gains optimised to minimise the occupant vibration. The gains were optimised using a genetic algorithm (GA), with a fitness function based on the seat effective amplitude transmissibility (SEAT) factor. Constraints on the control force and the seat suspension stroke were also included in the optimisation algorithm. Simulation and laboratory experimental tests were carried out to assess the performance of the proposed controllers according to the ISO 2631-1 standard, in both the frequency and time domains with a range of different road profiles. The experimental tests were performed using a multi-axis simulation table (MAST) and a physical active seat suspension configured as a hardware-in-loop (HIL) simulation with a virtual linear quarter vehicle model (QvM). The results demonstrate that the proposed controllers substantially attenuate the vertical vibration at the driver’s seat compared with both a passive and a proportional-integral-derivative (PID) active seat suspension and thus improve ride comfort together with reducing vibration-linked health risks. Moreover, experimental results show that employing both feedforward information and feedback vehicle body and seat acceleration signals in the controller provides isolation performance gains of up to 19.5 dB over the human body sensitivity frequency range and improves the ride comfort in terms of the SEAT factor and the weighted root mean square (RMS) seat acceleration by at least 25% when compared with a passive system, irrespective of vehicle forward speed.
Highlights
It is well known that the human body is sensitive to whole body vibration (WVB)over a frequency range of 4–8 Hz in the vertical direction caused by road roughness transmitted via the vehicle body
In this study, the fitness function that was used in the gain optimisation process was based on the seat effective amplitude transmissibility (SEAT) factor, which is defined as the ratio between the acceleration at the seat to that at the base of the seat [1]
In this paper five simple and cost-effective control strategies (A1 to A5) for an active seat suspension system have been developed in order to reduce the vertical broadband vibration (1–20 Hz) transmitted to a driver as a result of road excitation
Summary
It is well known that the human body is sensitive to whole body vibration (WVB). The experimental results of applying this control approach for a semi-active suspension system using a magnetorheological damper (MRD) showed a better vibration attenuation performance compared with passive and other alternative suspensions. The preview information that is used in this active seat controller is based on the dynamic changes in the vehicle secondary (spring/damper) suspension, together with feedback states obtained or derived from available measurements. In the paper presented here, a further five simple and novel active seat suspension controllers using preview information from the vehicle suspension states, as well as available feedback states from the seat are proposed The performance of these active suspension controllers is demonstrated initially through simulation and is validated through experimental tests
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