Preview-based techniques for vehicle suspension control: a state-of-the-art review

Abstract Automotive suspension systems are key to ride comfort and handling performance enhancement. In the last decades semi-active and active suspension configurations have been the focus of intensive automotive engineering research, and have been implemented by the industry. The recent advances in road profile measurement and estimation systems make road-preview-based suspension control a viable solution for production vehicles. Despite the availability of a significant body of papers on the topic, the literature lacks a comprehensive and up-to-date survey on the variety of proposed techniques for suspension control with road preview, and the comparison of their effectiveness. To cover the gap, this literature review deals with the research conducted over the past decades on the topic of semi-active and active suspension controllers with road preview. The main formulations are reported for each control category, and the respective features are critically analysed, together with the most relevant performance indicators. The paper also discusses the effect of the road preview time on the resulting system performance, and identifies control development trends

Adaptive interval type-2 fuzzy logic systems for vehicle handling enhancement by new nonlinear model of variable geometry suspension system

This research examines the emerging role of adaptive interval type-2 fuzzy logic systems (AIT2FLS) versus adaptive type-1 fuzzy logic system (AT1FLS) in vehicle handling by a new nonlinear model of the variable geometry suspension system (VGS) as a vehicle active suspension system. A proper controller is needed in order to have soft response and robustness against challenging vehicle maneuvers. Two controllers, including AT1FLS and AIT2FLS have been used in the paper. The proposed AIT2FLS can efficiently handle system uncertainties, especially in the presence of most difficult challenging vehicle maneuvers in comparison with AT1FLS. The interval type-2 fuzzy adaptation law adjusts the consequent parameters of the rules constructed on the Lyapunov synthesis approach. For this purpose, the kinematic equations are obtained for the vehicle double wishbone suspension system and they are substituted in a nonlinear vehicle handling model with eight degrees of freedoms (8DOFs). Thereby, a new nonlinear model for the analysis of VGS is obtained. The results indicate that between the two controllers, the proposed AIT2FLS has better overall vehicle handling, robustness and soft response

Modeling, Analysis, and Optimization Issues for Large Space Structures

Topics concerning the modeling, analysis, and optimization of large space structures are discussed including structure-control interaction, structural and structural dynamics modeling, thermal analysis, testing, and design

Multivariable Loop-Shaping in Bilateral Telemanipulation

Abstract This paper presents an architecture and control methodology for obtaining transparency and stability robustness in a multivariable bilateral teleoperator system. The work presented here extends a previously published single-input, single-output approach to accommodate multivariable systems. The extension entails the use of impedance control techniques, which are introduced to render linear the otherwise nonlinear dynamics of the master and slave manipulators, in addition to a diagonalization multivariable loop shaping technique, used to render tractable the multivariable compensator design. A multivariable measure of transparency is proposed based on the relative singular values of the environment and transmitted impedance matrices. The approach is experimentally demonstrated on a three degree-of-freedom scaled telemanipulator pair with a highly coupled environment. Using direct measurement of the power delivered to the operator to assess the system's stability robustness, along with the proposed measure of multivariable transparency, the loop-shaping compensation is shown to improve the stability robustness by a factor of two and the transparency by more than a factor of five. Fite and Goldfarb Multivariable Loop Shaping … 2 Introduction Bilateral teleoperation systems provide for human interaction with an environment while alleviating the necessity of direct contact between the two. Using a pair of robot manipulators, such a system enables dexterous human manipulation in remote, hazardous, or otherwise inaccessible environments. Bilateral telemanipulators can additionally incorporate power attenuation or amplification between the human operator and environment, allowing for human manipulation of microscopic objects (in the case of macro-micro bilateral telemanipulation) or large-scale objects (in the case of man-amplifiers). The teleoperative performance can be characterized by the transparency, which is a measure of the extent to which the telemanipulation system presents the undistorted dynamics of the environment to the human operator. A common goal in the control of bilateral telemanipulation is to provide transparent teleoperation while ensuring the robust stability of the human-telemanipulator-environment loop. Prior Work Several researchers have investigated aspects of transparency and stability in telemanipulation, primarily through the use of two-port network modeling techniques. Doyle [7], to assess the stability of a macro-micro bilateral telemanipulator interacting with a passive human operator and environment. Though the telemanipulator itself was a singledegree-of-freedom system, the human-teleoperator-environment interaction was formulated in a manner that required multivariable tools in order to assess stability robustness. Colgate did not explicitly treat transparency, but instead utilized impedance shaping to intentionally alter the dynamics as perceived by the human operator through the telemanipulator. Itoh et al. experimentally implemented a six degree-of-freedom telemanipulator using passivity theory to address stability robustness, but instead of providing transparency, the telemanipulator was controlled to exhibit a task-oriented dynamic behavior specified in order to facilitate a particular telemanipulation task. Hashstrudi-Zaad and Salcudean theoretically assessed the performance and stability robustness of a three degree-of-freedom telemanipulator by incorporating a parallel force/position control to linearize and decouple the manipulators, and by assuming the human operator and environment to be decoupled, in which case the analysis reduces to that required for three decoupled single-degree-of-freedom systems. In contrast to the combined hybrid parameter/passivity based approach, the architecture proposed by Fite et al. [8] formulates the teleoperation system as a single feedback loop to which the tools of classical control theory can then be applied to address the performance and stability robustness. In so doing, the stability robustness of the system is addressed in a non-conservative manner, and the transparency is addressed only in the bandwidth of interest. This loop shaping approach was developed in a single input, single output context; since telemanipulation Fite and Goldfarb Multivariable Loop Shaping … 4 applications generally involve systems with coupled multiple degrees of freedom, however, such a method is of limited utility without extension to the multivariable case. As such, the work presented in this paper extends this previously published approach to the multivariable case of telemanipulation. Specifically, the extension entails the use of impedance control techniques to render linear the otherwise nonlinear dynamics of the master and slave manipulators, and employs a diagonalization multivariable loop shaping technique used to render tractable the multivariable loop shaping compensator design. A multivariable measure of transparency is additionally proposed based on the relative singular values of the environment and transmitted impedance matrices. 3 Multivariable Telemanipulation Architecture Fite and Goldfarb Multivariable Loop Shaping … 6 Given the master/human and slave/environment dynamics as previously described, the loop shaping telemanipulation architecture is obtained by combining the master/human and slave/environment subsystems with the position and force scaling matrices, C 1 and C 2 , respectively, as shown in The transparency of the multivariable teleoperation loop is determined by the relative distortion between the transmitted impedance (i.e., the impedance felt by the human operator) and the actual environment impedance. The impedance transmitted to the human operator by the telemanipulation system is given by: For perfect transparency, the transmitted impedance transfer function matrix of Eq. (3) should equal the actual environment impedance, Z e . In practice, these matrices need only be similar within some frequency band of interest. Thus, within this band of interest, perfect transparency requires the singular values of the transmitted impedance transfer function matrix to equal those of the actual environment impedance transfer function matrix. As such, a measure of the desired multivariable performance can be given by the ratio of the respective singular values of the impedance transmitted to the human operator to those of the environment impedance: where n rank = ) ( e t Z , Z and i δ represents distortion in the teleoperative system. A desired bandwidth of transparency can be prescribed by ensuring that the distortion i δ in each singular Fite and Goldfarb Multivariable Loop Shaping … 7 value is less than some allowable amount of distortion ∆ for a desired bandwidth of operation. For ∆= 3 dB, a prescription for good teleoperative performance can be written as: where t Ω is a desired bandwidth of teleoperative transparency. The overall objective of the control architecture is to achieve the desired performance specified by Eq. (5) while ensuring the robust stability of the closed-loop system. With the introduction of a loop shaping compensator in the motion communication channel, th