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Post by tronicgr on Nov 26, 2014 21:09:13 GMT
Its not just theory anymore... Here is short clip I took a few days ago during remotely programming on such platform with Clearpath servomotors: www.youtube.com/watch?v=dEfwrW9rvjsI'm using position control for it (Burst Pulse mode), that it does not need external sensors... meaning no position sensors are required for the AMC1280USB... Thanks Thanos
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Post by mhensen on Nov 26, 2014 23:10:49 GMT
I think this is quite interesting as it removes the need of VFD's and 220V.. Can we have more details on this subject. like what motors used and how much weight it would be able to hold? And do we still need the gearbox , if still needed, what gearbox?!.. Couldn't see it quite clearly on the vid.. Don't know what the min NM is to lift 150-200 KG.. Looking at video it would have enough speed for a race simulator platform..
Importing these motors to the Netherlands would probably cost me almost the same as getting motors, gearboxes and VFD here. And probably it would be easier to set up..
So all in all .. great job and looking forward to any additional information.. Perhaps this would be my route.. Seems all very compact there or perhaps we only have half the picture :-)
With kind regards,
Michael
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Post by tronicgr on Nov 26, 2014 23:39:32 GMT
mhensenThese servomotors work by sending pulses that indicate the relative position, and tracking the actual position internally in the AM1280USB. I don't need to be precise on the width of the pulses or their duration. I can have the pulses interrupted and resume if I need to so I don't block the operation of the AMC1280USB. For the AMC1280USB to generate all the pulses needed the timing can be from 100uS (short distances) to 1.5mS (full CW position to full CCW position). I only control the position, but by toggling the enable port once I can set alternative slow speed for the offline mode so the motors can park slowly. As you can see on the video, the motors do use a gearbox. The gearboxes that are being used are 30:1. So I have to count in the pulses the gearbox as well, so I multiply the range of pulses to cover multiple rotations of the motor to get close to the 180 degrees rotation. There are enough pulses to cover many rotations at the time. The internal pulse buffer of the servomotor can handle up to 51000 pulses per revolution of the motor. I use only 800 pulses per revolution. There is no drifting at all as the servo motors have internal counter to measure the actual position and maintain the position even if you force it out of position (it will return to its target!). Also it features a homing function that is activated every time you enable the motor (I enable the motor once during power up). There is no PID on the AMC1280USB for these motors... I just calculate and send positions, and their internal PID does the job. Only downside, you need to do changes to their internal PID settings you need to do it manually 6 times with the USB cable they supply... They feature auto-calibration and adjustable max RPM speed and acceleration, as well adjustable torque limits. The motors will also re-generate power that is placed back to the capacitors of the power supply during their downward motion (driven by the load) so the can store extra power for reuse later. Really efficient motors!! The TWO HUGE power supplies an be seen placed on the front of the platform in the video... Depending on the servomotor, other servomotor and servo drives may be compatible or not with the control method I mention above. In many cases you can still use most of these servomotors with velocity control and close the loop to the AMC1280USB using external position sensors. Thanks Thanos
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