Hansong Xiao

Integrated control of active suspension system and electronic stability programme using hierarchical control strategy: theory and experiment

Integrated vehicle dynamics control has been an important research topic in the area of vehicle dynamics and control over the past two decades. The aim of integrated vehicle control is to improve the overall vehicle performance including handling, stability, and comfort through creating synergies in the use of sensor information, hardware, and control strategies. This paper proposes a two-layer hierarchical control architecture for integrated control of the active suspension system (ASS) and the electronic stability programme (ESP). The upper-layer controller is designed to coordinate the interactions between the ASS and the ESP. While in the lower layer, the two controllers including the ASS and the ESP are developed independently to achieve their local control objectives. Both a simulation investigation and a hardware-in-the-loop experimental study are performed. Simulation results demonstrate that the proposed hierarchical control system is able to improve the multiple vehicle performance indices including both the ride comfort and the lateral stability, compared with the non-integrated control system. Moreover, the experimental results verify the effectiveness of the design of the hierarchical control system.

Integrated control of automotive electrical power steering and active suspension systems based on random sub-optimal control

This paper addresses the problem of integrated control of electrical power steering systems (EPS) and active suspension systems (ASS). Through integrating EPS with ASS, a full car dynamic model is established. Based on the integrated model, a random sub-optimal control strategy based on output feedback is designed to fulfil the integrated control of both EPS and ASS. The characteristics of the integrated control system are analysed using Matlab/Simulink and a series of comparisons are made with the system without control and the ASS-only/EPS-only system. The simulation results show that the integrated control scheme can not only enhance the steering quality, but also significantly isolate the road excitation. Moreover, the integrated control system has a great improvement on anti-roll and anti-pitch abilities. The proposed research provides a theoretical solution for simultaneously improving the multiple vehicle performance indices including manoeuvrability, handling stability, ride comfort, and safety.

A New Constrained Multiobjective Optimization Algorithm Based on Artificial Immune Systems

This paper proposes a new constrained multiobjective optimization algorithm based on artificial immune systems (AIS). To deal with constrained multiobjective optimization problems, the constrained AlS-based multiobjective optimization algorithm is developed by integrating a proposed constraint-handling technique with the unconstrained AIS-based multiobjective optimization algorithm named MOAIS (Xiao and Zu, 2006). We propose the constraint-handling technique by extending a single-objective constraint-handling technique called stochastic ranking (Runarsson and Yao, 2000) to multiobjective optimization process. Two scenarios of the multiobjective version of stochastic ranking are suggested. Thereafter, we develop the constrained MOAIS named MOAIS+SR by integrating the two scenarios with MOAIS. A comparative study is performed quantitatively to assess the performance of MOAIS+SR on a constrained test function suite called CTP test problems. In the comparative study, MOAIS+SR is compared against two other constrained multiobjective algorithms. The simulation results show that the proposed multiobjective stochastic ranking outperforms the constrained-dominance principle (Deb et al., 2000) in handling constraints. Furthermore, we show that the proposed MOAIS+SR achieves the best overall performance among the three algorithms under consideration on the CTP test problems. This study demonstrates that the proposed MOAIS+SR is highly competitive with other state-of-the-art algorithms in constrained multiobjective optimization.

Integrated vehicle dynamics control through coordinating electronic stability program and active suspension system

This paper investigates integrated vehicle dynamics control through coordinating active suspension system (ASS) and electronic stability program (ESP) in order to improve the overall vehicle performance including handling, stability, and comfort. A two-layer hierarchical control architecture is proposed to integrated control of the two chassis control systems. The upper layer controller is designed to coordinate the interactions between the ASS and the ESP. While in the lower layer, the two controllers including the ASS and the ESP, are developed independently to achieve their local control objectives. Simulation investigation is performed to demonstrate the effectiveness of the proposed hierarchical control system. Results show that the proposed hierarchical control system is able to improve the multiple performance indices of the vehicle including both the ride comfort and the lateral stability, compared to the non-integrated control system.

Fillet Shape Optimization for Gear Teeth

In this paper, the fillet shape optimization problem is studied using a new shape optimization approach. In order to achieve the optimal performance of gear mechanism, the maximum bending stress is minimized in the fillet region. In the proposed shape optimization approach, there are two new contributions: the application of Boundary Element method (BEM) and B-spline representation of the fillet shape. A Boundary Element model is established for the gear tooth and the bending stress in the fillet region is evaluated by a Boundary Element solver. The use of BEM in the approach instead of the commonly used Finite Element Method (FEM) has significant importance for shape optimization since BEM usually provides more accurate structural responses on the boundary and the remeshing procedure is much easier. For the curve representation of the fillet profile, the uniform cubic B-splines are employed in fillet profile synthesis. The fact that B-spline curves are used to construct the design boundary overcomes limitations resulted from the discrete nodes representation. Therefore, this new approach combines both the BEM solver and the B-spline technique in the shape optimization process. In an example for numerical simulation, a non-involute gear tooth profile is used and the results show that the new shape optimization technique is efficient for optimizing the performance of the gear mechanism. Moreover, the proposed shape optimization approach is able to provide reliable solutions for optimizing a large variety of the non-standard gear tooth profiles.Copyright

Integrated Control of Vehicle System Dynamics: Theory and Experiment

Modern motor vehicles are increasingly using active chassis control systems to replace traditional mechanical systems in order to improve vehicle handling, stability, and comfort. These chassis control systems can be classified into the three categories, according to their motion control of vehicle dynamics in the three directions, i.e. vertical, lateral, and longitudinal directions: 1) suspension, e.g. active suspension system (ASS) and active body control (ABC); 2) steering, e.g. electric power steering system (EPS) and active front steering (AFS), and active four-wheel steering control (4WS); 3) traction/braking, e.g. anti-lock brake system (ABS), electronic stability program (ESP), and traction control (TRC). These control systems are generally designed by different suppliers with different technologies and components to accomplish certain control objectives or functionalities. Especially when equipped into vehicles, the control systems often operate independently and thus result in a parallel vehicle control architecture. Two major problems arise in such a parallel vehicle control architecture. First, system complexity in physical meaning comes out to be a prominent challenge to overcome since the amount of both hardware and software increases dramatically. Second, interactions and performance conflicts among the control systems occur inevitably because the vehicle motions in vertical, lateral, and longitudinal directions are coupled in nature. To overcome the problems, an approach called integrated vehicle dynamics control was proposed around the 1990s (Fruechte et al., 1989). Integrated vehicle dynamics control system is an advanced system that coordinates all the chassis control systems and components to improve the overall vehicle performance including safety, comfort, and economy. Integrated vehicle dynamics control has been an important research topic in the area of vehicle dynamics and control over the past two decades. Comprehensive reviews on this research area may refer to (Gordon et al., 2003; Yu et al., 2008). The aim of integrated vehicle control is to improve the overall vehicle performance through creating synergies in the use of sensor information, hardware, and control strategies. A number of control techniques have been designed to achieve the goal of functional integration of the chassis control systems. These control techniques can be classified into two categories, as suggested by (Gordon et al., 2003): 1) multivariable control; and 2) hierarchical control. Most control

Evolutionary multi-objective optimisation of cam profile for a new cam drive engine

As an essential research effort in developing a new cam drive engine, this study investigates a complex multi-objective cam shape optimisation problem for a unique cam mechanism in the cam drive engine. A uniform B-spline representation is developed to construct the cam shape. Moreover, an evolutionary multi-objective optimisation approach is applied to solve the problem. The optimisation results show that the overall engine performance is improved significantly by the evolutionary multi-objective optimisation approach compared to the initial design. In the meantime, the ease and flexibility of the optimisation approach in solving this complex cam shape optimisation problem are demonstrated.

Hierarchical control of automotive electric power steering system and anti-lock brake system: theory and experiment

This paper studies integrated control of chassis control systems to achieve the goal of functional integration of the control systems. A two-layer hierarchical control architecture is developed for integrated control of Electric Power Steering (EPS) system and Anti-Lock Brake System (ABS). The upper-layer controller is designed to coordinate the interactions between the EPS system and the ABS. In the lower layer, the two controllers including the EPS system and the ABS are designed independently to achieve their local control objectives. Both a simulation investigation and an on-vehicle experimental study are performed to demonstrate the effectiveness of the proposed hierarchical control system. Simulation results show that the system is able to improve the lateral stability of the vehicle, and at the same time ensure the steering agility and braking performance of the vehicle. Moreover, on-vehicle experiment results conform to the simulation results.

Integrated Control and Coordination of Vehicle System Dynamics

Current and future motor vehicles are incorporating more and more sophisticated chassis control systems to improve vehicle handling, stability and comfort. These control systems often operate independently and thus interactions and performance conflicts among the control systems occur inevitably. To address the problem, this study proposes a two-layer hierarchical control architecture for integrated control of electric power steering (EPS) system and anti-lock brake system (ABS). The upper layer controller is designed to coordinate the interactions between the EPS system and the ABS. While in the lower layer, the two controllers including the EPS system and the ABS, are designed independently to achieve their local control objectives. Simulation results show that the proposed hierarchical control system is able to improve the vehicle lateral stability, and at the same time ensure the vehicle steering agility, and the braking performance.Copyright

Integrated Vehicle Dynamic Control Through Coordinating Control of Steering and Suspension System

This paper addresses the problem of integrated control of Electrical Power Steering System (EPS) and Active Suspension System (ASS). Through integrating EPS with ASS, a full car dynamic model is established. Based on the integrated model, a random sub-optimal control strategy based on output feedback is designed to fulfill the integrated control of both EPS and ASS. The characteristics of the integrated control system are analyzed using Matlab/Simulink and a series of comparisons are made with the system without control and the ASS-only/EPS-only system. The simulation results show that the integrated control scheme can not only enhance the steering quality, but also significantly isolate the road excitation. Moreover, the integrated control system has a great improvement on anti-roll and anti-pitch abilities. The proposed research provides a theoretical solution for simultaneously improving the multiple vehicle performance indices including maneuverability, handling stability, ride comfort, and safety.Copyright