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Post by Trip Rodriguez on Sept 12, 2014 11:35:41 GMT
It turned out the torque numbers I'd been given on those servo motors I was buying were peak and not continuous. Good thing I looked up the data on them via the manufacturers website! So now I'm back to choosing motors.
I'm still serious about the ClearPath servo motors if they put out enough power but it's hard to tell. If they won't do for 6DOF I might be back to AC motors. I've been scared off by the need for 220VAC supply but I see nearly all the good 6DOF rigs people here have built used AC motors.
Can anyone give me a good idea how many watts I need per motor for a 6DOF hexapod rig moving a 70KG (150lb) platform with a 77KG (170lb) pilot? I'm going to start shopping again.
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Post by tronicgr on Sept 16, 2014 23:05:08 GMT
The Clearpath servomotors DO have enough torque for 6DOF, You just need the proper reduction gearbox to amplify their torque to match the torque of the AC motors. I'll give you and example -AC motor (0.75HP) : MTR-P75-3BD18 RMS Torque: 1.52 lbs/ft -BLDC Servomotor CPM-MCVC-3441S-RLN RMS Torque: 2.49 lb-ft Another difference: -The AC motors are free wheeling when they reach the target and a "stop" command is issued. (they may bounce around the target if there is backlash in the reduction gearbox.), Manual calibration of PID values on the AMC1280USB controller may needed to avoid or minimize this. -The Servomotors, will "brake" instantly when the reach the target, and HOLD position themselves (secondary position control from the integrated drive and enclosed quadrature encoder inside the motor). There is a Auto-calibration feature that you can run on the motors and they WILL calibrate themselves under load (6DOF platform connected with load on it). Thanos
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