At the top of each hour, a proprietary controller sends a signal via RS-485 link to twin controllers, causing them to execute a motion profile program that drives each of two sculptures. A NEMA 34 stepper motor running in the open-loop mode in conjunction with a 15:1 right angle gearhead provides enough torque to drive the system. An open gear reduction of 5:1 between the gear-head output pinion and the slewing ring gear on the stage platen maintains a favorable inertia ratio between the rotating sculpture and the motor. This configuration allows the system to accelerate the sculptures at approximately 1 rev/sec2 to speeds in excess of 20 rpm when executing their motion profile. The completed rotary stage is repeatable to plus or minus 2 degrees, with most of the position error due to backlash in the open gearing comprising the final stage of the drive train. The easy programmability of the ZETA system allowed for a dynamic and realistic motion profile.
|For more information on Electric Time's 99B-MI Clock Controllers, go to http://rbi.ims.ca/3849-562|