The Liverpool Telescope is a 2.0 metre robotic telescope that is operating unattended at the Observatorio del Roque de Los Muchachos, Spain. This paper gives an overview of the design and implementation of the telescope and its instrumentation and presents a snapshot of the current performance during the commissioning process. Science observations are under way, and we give brief highlights from a number of programmes that have been enabled by the robotic nature of the telescope.
The design of high performance motion control systems for large telescopes is an area of major interest. To counteract the effects of parameter variations and uncertainties as well as wind buffeting a robust controller must be designed. This paper outlines an approach for designing H-infinity controllers for the main axes of a class of telescopes. Some choices made during the controller design are briefly considered. The impact on system performance arising from structural resonance, wind buffeting, drive train stiffness and drive stiction are discussed. The controllers are developed from state space models that include wind disturbances. Davenport wind power spectrum is used to characterize wind buffeting. Sub-optimal H-infinity controllers are designed using standard tools in Matlab. The controllers are designed to operate in continuous time but for implementation they are discretized with a sampling time interval of 2.5 milliseconds. Experimental results for both azimuth and altitude are presented and discussed. A summary of RMS servo errors for tracking and pointing is also included.