OpenServo.com

[wakeMeUp]

Hey everyone,
I really like the hermite curve following features of the OpenServo, but I'd like a continuously rotating system, and I'd like to use larger motors than RC servos...

I am trying to find some sort of motor / drive system, be it a servo or a stepper etc that could push a small dolly for a camera along some rails. It would need to be able to push about 1 to 2 kg, and since its on rails, I am hoping there will be little friction.

Obviously a stepper solution would be straight forward for this kind of thing, but what would be great to have is the same hermite curve position following features of the OpenServo in a larger package.

Does anyone know of any products / ways of achieving this? Would it be possible to buy a servo drive and motor (the kind used for cnc milling type stuff), and connect some sort of input from a board/ microprocessor, based on OpenServo code?

Hope what I am trying to achieve is clear, and I would really appreciate, input / ideas.

Thanks,
David!

[ginge]

Hi David, and welcome to OpenServo.

Although the main focus of OpenServo is for driving small servo motors, I have recently developed a stepper motor driver board, and the relevant firmware to make the magic happen.

The board supports a stepper motor up to 2A/phase at up to 46V, and is normally enough to drive most bipolar stepper motors. Alternatively, the board can be configured to run a single 4A (standard) motor.

The product is not available yet, as I am still awaiting the PCBs back from the shop, but as soon as they arrive, and the board is tested to destruction, I will be posting up all schematics and plans.They will also be available through the webshop.

If you wanted to roll your own solution, you can use the code in the OpenServo package to drive a stepper motor driver board, such as a CNC mill. In order to do that you will need a driver with a full step (4 input) interface, as there is no code support for step/direction as yet. It should be easy enough to change the current CVS code to support the step/direction mode if needed.
The OpenServo step code is very alpha, but it does work. The step code outputs the step patterns on the port of your choice, so should be compatible with anything that supports simple step interfacing, such as the L298 step drive chip.

Currently we don't support continuous rotation, as OpenServo is a closed loop control system based on finite rotation potentiometers. I will be putting some development into continuous rotation in a short amount of time to support a project I am working on, and the code changes should be fairly insignificant. Famous last words!

Barry
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