Bilateral control: a sliding mode control approach

Official URL: http://risc01.sabanciuniv.edu/record=b1143159 (Table of Contents)

Bilateral control is bi-directional control of force-position between two systems connected by a communication link. It is typically used for teleoperation with forcefeedback, such that the master system is handled by an operator. Motions of the operator are fed forward to the slave system, generally remote to the operator and forces encountered are fed back to the master system, enabling a telepresence of the operator in the remote environment. The necessity of bilateral control lies in its applicability to the tasks that cannot be handled by autonomous manipulators and/or reached by human beings. Main issues of consideration for bilateral control, namely transparency, scaling and time delay, are addressed and two discrete-time sliding-mode approaches are presented as solutions to highly transparent bilateral controllers that support scaling. First approach has a force-hybrid architecture, where the cascaded sliding mode hybrid force/position controller on the slave side reacts to the external forces directly. Therefore, it provides a protection (reflex) mechanism on the slave side to large external forces, that the operator cannot respond in time due to the time delay. Second approach has a decentralized nature. Virtual systems are devised by a linear transformation from the plant space to the task space and sliding mode control has been applied to those virtual systems, hence sides of bilateral control are interchangable. The decentralized structure of the controller makes it possible to generalize the problem to a coordination and/or cooperation of more than two plants. High precision has been achieved on experiments for both approaches designed and discussed in detail.