Control system design of multivariable non‐linear space robots

Abstract

PurposeThe paper's purpose is to initiate an effort that will result in a systematic approach for design of control systems for multivariable, nonlinear, and unstable space robots.Design/methodology/approachThe design approach is based on multivariable describing function (DF) models of the space robot coupled with the use of factorization technique. The design approach is to obtain the multivariable DF models followed by application of a previously developed factorization‐based controller design formula. Finally, the design must be verified by a non‐linear simulation to make sure that approximations made during design are valid.FindingsIt is found that the DF approach may successfully be applied in order to control nonlinear, multivariable, and unstable systems such as space robots.Research limitations/implicationsAt present, the approach is verified to be applicable to rigid space robots.Practical implicationsThe major outcome of this research is that complicated controllers of a class of space robots may be replaced by simpler controllers, taking into account the amplitude dependency features of the space robot; this amplitude dependency is the most important characteristic of a non‐linear system.Originality/valueThis is the first paper in the area of multivariable and unstable space robot controller design that is based on the application of the DF technique. In fact this is the first work in the area of general unstable non‐linear control system design that is based on a DF technique.

Single‐range controller design for a cruise missile

“…In Taylor (1983), a describing function‐based controller design platform is introduced. This platform has been developing ever since: Taylor and Strobel (1985), Taylor and O'Donnel (1990), Nassirharand and Karimi (2005), Mousavi Firdeh et al (2006) and Nassirharand (2008). Competitive work has also been reported in Atherton et al (1993).…”

“…Most of the works on controller design for nonlinear systems based on describing function models have been limited to single‐variable systems. Recent advances on application of describing function technique to multivariable nonlinear systems have been reported in Colgren (2004), Mousavi Firdeh et al (2006) and Nassirharand (2008).…”