Quote:
Originally Posted by bert
Chris, I buy the k8055 from ocean controls in melbourne pre-assembled, I have been happy with their service.
You can use Gray code scaling which is preferrable to using a on/ off encoder. The gray code does provide some error correction from overrun after the motor has stopped but the dome inertia moves it further. Using the k8055 board you can use the gray code or a simple on/off transition, remembering the overrun errors will be reset every time the dome passes the home switch. Most dome manufacturers do not use gray code, rather the simple on/off transition and rely on the home switch to reset errors that have accumulated over time.
Brett
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Thanks Brett and Steve, I'll have to find out more on these boards. At present, I'll concentrate on finding a suitable drive arrangement, but keep in mind the need to be able to control it automatically and/or remotely in the future. The Arduino boards mentioned in another thread also sound good with a few more I/O.
Steve, I agree entirely with your assessment of the potential benefits of using two drives rather than just one. I have just three centering wheels and I'm sure that some of the torque effort is wasted on lateral thrust. My dome "wanders" just a little, and whilst it generally rotates nicely, it occasionally "binds" a bit; this may be a temperature effect. I used a spring balance to measure the force required to start it rotating (8 kg = 80 N), and then to sustain rotation (4 kg = 40 N). I reckon that that's not too bad for nearly quarter of a tonne!
Chris