Motor Technology is 25 years old this year, and we’re celebrating by looking back at some of the most exciting projects we’ve been involved with during that time.

We’ve designed and installed systems for some of the greatest names in industry, research, education, theatre, and film, and we’d like to thank all our customers, old and new, for their support. It’s a cliché perhaps, but without you we wouldn’t be where we are today.

In this month’s issue of Motor Technology News we’re looking back to the summer of 1998 when scenery fabricators Streeter & Jessel approached us to develop a highly sophisticated automation system for, of all things, a flying mirror.

This was not just any old mirror though. This mirror was three metres high by six metres wide and weighed in at 1,000kg! It was to form the centrepiece of the set during a performance of Life is a Dream, by Spanish playwright Calderon, staged by the Lyceum Theatre Company at the Edinburgh Festival, starring Sylvester McCoy of Doctor Who fame.

In the opening scene the vast mirror lies face down on the stage, covered by a large quantity of grey sand, and then rises to a height of 2m allowing the actors to appear from a trap door underneath. Once the actors are on stage the mirror tips backwards allowing the sand to cascade from the back, creating an attractive rain-like effect.

During the rest of the performance the mirror was required to move swiftly and smoothly through additional sequences before finally returning to the stage at the close of the final act.

The automation solution had to achieve repeatable positional accuracy of 4mm over a 9m drop, and at all times the safety of the actors on stage had to be given utmost priority.

A steel gantry was constructed that could be rigged above the stage and the mirror was suspended by bowden cables and winched into a range of positions using 6 axes of servo drive motion control. Motor Technology supplied the drives, motors, worm gear boxes, and a user interface that was custom-designed for the application.

The system architecture was developed using Eurotherm’s 637 series intelligent servo drives and utilizing the local fieldbus easy-serial RS485. The user-interface, developed by Motor Technology, allowed fast positional updates for each axis, comprehensive error handling, and an intuitive operational environment which could be used to develop a performance program complete with stage cues. Any system, bus errors or e-stops would disable the drives and cut off the power supply activating the motors’ internal brakes.

Orders were placed with Motor Technology during the first week of July and the design, construction and installation was completed by 6 August in time for the start of the festival.

mirror was three metres high by six metres wide and weighed in at 1,000kg