Sliding door torque/load simulator.

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We design and manufacture electronic controls for large industrial sliding doors. These doors present a large inertial load to the controls, and to test these properly we have designed the small dynamic test fixture shown in this video. The door inertia is simulated by placing varying weights on the swing arm. The friction is simulated by tightening the band on the friction roller. This friction band is also automatically tightened down by a small 1 inch cylinder controlled by a small PLC (not visible in the video). A proximity sensor counts the arm revolutions and applies the full load at the simulated ends of the travel. Sliding doors are unique in that they typically do not have sensors to indicate the opened and closed position, rather they bump up against the end travels during and initial "reset cycle", and use the sudden increase in torque to determine the end positions of the travel. The setup for this door uses a 1/3HP, 24VDC brushed gear motor manufactured by Groschopp. Our extensive design and analysis determined that a 15:1 right angle gear motor was well suited to the moving doors up to 800 lbs, providing fast and controlled travel. The sliding doors are unique in that they sense obstructions in their path by monitoring the torque load (as when finding the end positions). The right angle worm gear, though providing very low power efficiency, provides excellent stopping characteristics, and dissipates inertia internally and limits the complexity of dynamic braking and the effects on the DC bus voltage. The system can stop a fast moving door with only a few pounds of pressure using a custom torque profiling algorithm. Our power door controller is enclosed in a carefully designed and optimized aluminium enclosure. This project required considerable development, and the controls are based on a fast 100 MHz ARM processor/power board. The complete system has this main control module, a custom 650VA power source based on a custom toroid transformer and power rectifier/filter chassis, and also a custom 2X20 LCD display module which can be placed locally or remotely via an RS485 link. The complete system is programmable, similar to a standard VFD, but with functions appropriate the sliding door application, and also provides near-servo like positioning performance with a relatively low cost and powerful standard DC gear motor. The complete OEM sliding door controller is not shown in this video, but if you are interested in some still pictures leave a note or contract Smart Electronics. This fixture was very key to the successful design of the controller, and it's continued updates and development and I would like to thank Butty Manufacturing (George) for his patience and professional assistance with this fixture.