New Drive and Control systems for the E-Systems Telescopes

The Darnhall E-System Telescope.

The original control and drive system for the telescope comprised an antenna control unit (ACU) which was provided with positional commands from the on-site control computer. The ACU compared these commands (in both Azimuth and Elevation) with the positions derived from the encoder systems on each axis.   The ACU then provided drive signals for the motor drive control systems to move the telescope.

In 1997 the Pickmere Telescope ACU, which was a complex piece of digital hardware, became unreliable and a crash programme was instituted to bypass it and control the motors directly from the on-site control computer.   This was aided by the fact that new encoder systems had been implemented which could interface directly to the control computer.   A system to transfer the required drive rate commands from the on-site computer to the motor control system was built and so the telescope servo control was made part of the on-site computer software.

The ACU had thus been bypassed but the motor drive control circuitry and the drive motors were still original.   The system has operated well since Easter 1997 and forms the basis of the complete upgrade that will be applied to the Darnhall Telescope.   The original motor drive circuitry will be replaced by new Eurotherm drive contol units and new motors installed.