PolyU research team led by Dr XJ Jing from the Laboratory of Nonlinear Dynamics, Vibration and Control, Department of Mechanical Engineering, takes further steps into critical industrial issues with benchmark advance achieved recently of increasing industrial impact. A series of benchmark results are recently developed and some of them have been accepted and published in:

In the past several decades, suspension systems, as a critical part of vehicle chassis, which can perform significant influence on the ride comfort and vehicle manoeuvrability, obtained more and more popularity and attention in automotive industry. Compared with passive and semi-active suspension systems, an extra actuator is installed in an active suspension system to generate or dissipate energy; and thus, much better vibration isolation effect can be obtained. However, the energy cost and tough requirements on efficiency, robustness and reliability of actuation systems are becoming more and more critical issues in practical application (Figure 01).

Figure 01: Active suspension systems of advanced modern vehicles

Traditional control methods usually only target at high performance without sufficient consideration on the energy cost, and thus have obvious limitation in various practical applications. To solve the problem, Dr Jing’s research team established a unique adaptive and robust control scheme for active suspension systems with neural networks, fuzzy logic and/or others. The new control scheme can intentionally employ inherent nonlinear dynamics of vehicle systems and address several critical engineering issues simultaneously, including energy efficiency, input delay/saturation, loading change, and/or unknown/uncertain dynamics etc, which are all challenging problems in engineering practices.

The significant difference from most existing controllers lies in that, the designed controller can effectively utilize beneficial nonlinear stiffness and damping characteristics introduced by a novel bioinspired reference model (Figure 02), and thus purposely achieve superior vibration suppression and obvious energy-saving performance simultaneously. Theoretical analysis and experimental results vindicate that the proposed controller can effectively suppress vibration with much more improved control performance and considerably reduced control energy consumption up to or more than 44% (Figure 03, Table 01).

This should be for the first time to reveal both in theory and experiments that a superior suspension performance is obtained with simultaneously an obvious control energy saving, by employing beneficial bioinspired nonlinear dynamics, compared to most traditional control methods. It also provides a unique insight into many other robust controller designs in various engineering issues.

Figure 02: (a) A grus japonensis and its legs, (b) The mechanical diagram of the bioinspired reference model, (c) Deformation analysis (layer number n=2)

Figure 03: Vehicle body acceleration

Table 01: RMS OF THE ENERGY CONSUMPTION WITH RESPECT TO DIFFERENT ROAD PROFILES (W)

Controller Sinusoidal road profile Random road profile
ESOT controller 0.031 0.0027
Proposed controller 0.0264(↓14.84%) 0.0021(↓22.22%)
Proposed tracking controller 0.0125(↓59.68%) 0.0015(↓44.44%)

The industrial potential will be further explored by collaborating with automobile companies from mainland of China, including the GAC Group, which is a Chinese automobile maker headquartered in Guangzhou, Guangdong, and a subsidiary of Guangzhou Automobile Industry Group. Detailed technical collaboration is under negotiation.