Video's III
Some video's of the DIY Motion Platform III in action.

Complete system demonstration video's can be seen on Youtube:

Update system demonstration video:

First demonstration video:

Tweaking is never finished, but very nice results. The high frequency capability of the platform, also in heave, is quite good.

Initial tests with the new actuator design: results are shown in this video.

First tests with  3-channel DAC and servo drive are shown in 3DoF test movie clip
The drive for these tests was done via sine-wave shaped signals made in GWbasic. See Platform Testing Software.

Some issues that were found:

 1, The 3 actuators do not have the same speed when working in open loop (full load) condition. You can see this in the fast heave movement. Probably caused by the different load and different motor type of the front actuator. Actual flight shows that this effect is not so serious.  

2. There is some overshoot in the fast response. Improved by lowering servo Gain.

3. After sudden excursions, the platform tends to wiggle back and forth, as it is suspended in the V-belts. I tried tightening the belts, but still there. This could be annoying. Improved by adding a stabilizing rod. See update.

4. There is some noise (erratic behavior of the servo) at slow PWM movements. Caused by noise coupled in the small signal section of the servo drive. Visible on the scope as well.
This has been solved in the new version 2 Servo Drive and 4-channel DAC layout.

5. The position pick-up tends to 'shift' after some movements : Apparently there is some slip in the V-belt to bottom guide wheel. A more direct position pick-up method needs to be made.

I measured the battery power surge at fast heave movements: 25Amp at 36V = 900W. That's 300W per motor, should be OK.  See also platform drive calculations.


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