My transgender robodog fancat Bela, the big version with JX PDI-HV5523 HV servos is suffering of unpredictable erratic movements as discussed many times here when weak batteries are used. She fidgets heavily and there's danger of something breaking.
Bela uses a 25C 2S1P 2200 mAh Lipo, so I think the Lipo can't cause the problem.
Somebody has a hint for me where to look at? Is it possible that its caused by interference signals?
Bela is just a upscaled version of Catmini using the recent Nybble code.
5200mAh, 80 C Lipo -> +- 30 Minutes
how long does the battery last?
Still needs some calibration, but works :)
Same Type but the 9685 from different manufacturer. But was not the problem. It turned out that the SBEC that brings the voltage to 5 V is not a stable source.
Although the SBEC is supposed to deliver 20 A (JVSISM YPG 20A HV), the voltage seems to fluctuate with the known consequences.
The SBEC only supplies the electronics (+servo signal), the servos (+,-) I operate directly on the Lipo.
I have built in a Supercap 5.5V, 0.47F to buffer the voltage. Since then Big Bela behaves well.
I will now test and train, then I will show you what she can do. Thanks for your tireless support, Li. Xie Xie!
what are you using to replace 9685 and 6050?
Well, using a 5200mAh, 80 C Lipo and twisted the servo wires:
replaced the Arduino pro mini -> behaves even worse, behave strangely after connecting 8, 9 and 12. Replaced the PCA9685 -> works much better until I I connect the shoulder servos 6 and 7 (4 and 5 still left not connected) behaves strange again.
Next I will replace the MPU6050, I know it's doable!!!
Ok, thanks for the hint,I will give a try. Using a different (but weaker) lipo worked until now, but I did not test it much yet. And yes, its the sport micro body I choosed because its very stable and robust.
It looks like the spot micro project.
I think you can suspend it in the air to see how it behaves. Then hold its legs one by one. If it starts to behave strangely, it will prove it is reaching the battery's output limit.
Thank you for your reply! I supply the servos directly from the battery, the signal goes via the PCA9685 to the servos.
I supply the Arduino Pro Mini and the other parts with a JVSISM YPG 20A HV SBEC with 5V. I have not measured the current it draws when misbehaving. Was max. 1 Ampere when walking (kwk) for each leg (3 servos / leg). Must be much more when stalled but the lipo should can handle even that.
Hi, do you have a picture/video of your new robot? What circuit board are you using and have you measured the actual current or the voltage over the battery when it's moving?