Jerky Servos

Question

I have constructed my version of jd robot using EzB-v4 ,7.4v Lipo and hi torque 7.4v servos. Works well but the servos are jerky. They work fine individually. Any ideas? confused

DJ Sures · Answer

Can you explain more?

thetechguru · Answer

Do you have any ADC ports in your project? If so, how often are you reading them, and is your EZB a version 4 or the new 4/2? What is the MaH rating (and C rating if you have it) for the battery? The two most common issues with performance are flooding data channel, caused by too many reads on one or more ADC port, or insufficient battery current (although low current usually causes the EZ-B to brown out and disconnect vs jerky servo movement). You can post your project and we can take a look to see if there are any scripts that look troublesome. Alan

westies · Answer

Thanks for speedy response. The Lipo is 1300MaH,and 25C rating. Using EZ-B v4. I have constructed a JD robot using non-EZ servos,which are 7.4v rated. At the moment legs feet and shoulder servos are connected.when the leg servos operate they are rather jerky when moving.(they move freely and smoothly with no power to them). It is all connected as in the official JD Robot. Could it be due to speed of servos and if so how can they be altered.

Jeremie · Answer

Are these third party servos Digital or Analog?

westies · Answer

Digital. They work smoothly individually, the problems arise when they two or more work together. Incidentally they only draw around 200-500mA.

Jeremie · Answer

I'm assuming that the servos only "jerk" when you are executing actions, correct? So the default JD actions are designed around analog servos. To combat Digital servo jerkiness I would recommend changing the Speed, Delay, and Step values for each frame in the "Action" section of the Autoposition Control. Start with slowing down the Speed (0 is fastest and 10 is slowest), start with Speed:1, then increase your delay values until your action completes each frame in its entirety and lastly adjust the steps to create the smoothest response you can in relation to the delay value.

westies · Answer

Thanks for information. I wondered if speed may be linked to the problem. Will try your suggestions later in day.

DJ Sures · Answer

Continue using this thread and do not create duplicate threads for the same topic, thanks!

westies · Answer

Thanks DJ and Jeremie. Slowing down servos has improved the jerkiness. My only problem now is that changing the speed of servos in one action seems to change them in others. Is there a reason why analog servos rather than digital servos are used in the projects.

westies

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