Nonlinear control of hydraulic differential cylinders actuating a flexible robot

Bernzen, Werner; Wey, Torsten; Riege, Britta

doi:10.1109/cdc.1997.657643

Cited by 13 publications

(8 citation statements)

References 4 publications

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“…[14], [15]. For example, in [16] the change of volume and the tank pressure are neglected. In other contributions the leakage term is neglected, e.g.…”

Section: A Actuator Modelmentioning

confidence: 99%

A-priori Fisher information of nonlinear state space models for experiment design

Dietrich

Raatz

Hesselbach

2010

2010 IEEE International Conference on Robotics and Automation

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This article presents advances in optimal experiment design, which are intended to improve the parameter identification of nonlinear state space models. Instead of using a sequence of samples from one or just a few coherent sequences, the idea of identifying nonlinear dynamic models at distinct points in the state space is considered. In this way, the placement of the experiment points is fully flexible with respect to the set of reachable points. Also, a method for model-based generation of prediction errors is proposed, which is used to compute an apriori estimate of the sample covariance of the prediction error. This covariance matrix may be used to approximate the Fisher information matrix a-priori. The availability of the Fisher matrix a-priori is a prerequisite for experiment optimization with respect to covariance in the parameter estimates. This work is driven by the problem of parameter identification of hydraulic models. There are methods for hydraulic systems regarding the estimation of parameters from experimental data, but the choice of experiments has not been treated adequately yet. A hydraulic servo system actuating a stewart platform serves as an illustrative example to which the methods above are applied.

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“…[14], [15]. For example, in [16] the change of volume and the tank pressure are neglected. In other contributions the leakage term is neglected, e.g.…”

Section: A Actuator Modelmentioning

confidence: 99%

A-priori Fisher information of nonlinear state space models for experiment design

Dietrich

Raatz

Hesselbach

2010

2010 IEEE International Conference on Robotics and Automation

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“…It is assumed that L samplesŷ are taken from experiments which form the matrix of measured outputsŶ = ŷ [1] . .…”

Section: B Experiments Samplingmentioning

confidence: 99%

Numerical aspects regarding the a-priori Fisher information of nonlinear models for hydraulic servo-systems

Dietrich

Raatz

Hesselbach

2010

2010 IEEE/RSJ International Conference on Intelligent Robots and Systems

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This article adresses aspects of the a-priori computation of the Fisher information matrix. The aim of the type of Fisher matrix discussed is the experiment design for parameter estimation of nonlinear state space models. A definition for the sampling of experiments is stated, which is convenient for software implementation. Both, measurement samples that belong to a coherent sequence and samples from independent experiments, may be stored together in one single data structure. Since the covariance matrix of the prediction error is required in the Fisher matrix, a method for its a-priori prediction is proposed.A servo-hydraulic positioning system serves as a validation example. The comparison of the a-priori and a-posteriori Fisher matrices of this example show that the method proposed is suitable to provide an approximation of an optimality criterion for experiment design.

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“…There have been previous attempts at direct servo force control of these systems in the literature. However, most of these have either been purely simulation [7] or have been severely bandwidth limited [14]. Since force control was seen as a more challenging problem, the approach outlined in Section III was directed at controlling the force output of the cylinder shown in Fig.…”

Section: Application To An Electrohydraulic Servosystemmentioning

confidence: 99%

“…There has been a large amount of research done on the control of systems represented by (7). References [11], [17], [20], [29], and others have been investigating the control of these nonlinear systems using a variant on the I/O feedback linearization approach.…”

Section: A Systematic Controller Designmentioning

confidence: 99%

Systematic control of a class of nonlinear systems with application to electrohydraulic cylinder pressure control

Alleyne

Liu

2000

IEEE Trans. Contr. Syst. Technol.

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This paper develops a systematic methodology for the control of a class of nonlinear systems and applies it to an electrohydraulic system. The class of systems to be dealt with are those that are single input and can be put in strict feedback form. The approach is conceptually similar to previously developed integrator backstepping methodologies. However, unlike some previous investigations which have relied exclusively on a Lyapunov analysis, this work presents a stability analysis using a passivity formulation. There are two main advantages of the proposed approach which become significant during implementation. One practical advantage is that the resulting controller leads to synthetic inputs that are decoupled in a certain sense. This leads to a compartmentalization of modeling error effects associated with the controller. A second advantage of this method is that the system model need not be differentiated in the control formulation. A class of modeling error is introduced and compensated for with the resulting control able to guarantee specified boundary layer tracking. A nonlinear model is developed and verified for an electrohydraulic testbed consisting of a cylinder governed by a electronically controlled servovalve. Finally, the control algorithm is implemented on the testbed and a comparison is made with existing integrator backstepping algorithms. The comparisons demonstrate the benefits of the presented approach.Index Terms-Electrohydraulics, passivity-based control, strict feedback form systems.

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Nonlinear control of hydraulic differential cylinders actuating a flexible robot

Cited by 13 publications

References 4 publications

A-priori Fisher information of nonlinear state space models for experiment design

A-priori Fisher information of nonlinear state space models for experiment design

Numerical aspects regarding the a-priori Fisher information of nonlinear models for hydraulic servo-systems

Systematic control of a class of nonlinear systems with application to electrohydraulic cylinder pressure control

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