servo jittering in stabilization mode

Hello everyone!

We equipped an easy-star with an ArduPilot (with Shield V2) and AttoPilot XYZ IR-sensors, ArduPilot software 2.5 and 2.6 was used. We are using a HITEC optic6sport transmitter and a HITEC HFS-05MS receiver.

The problem is that when we change into the stabilization mode the servos begin to jitter (rudder more than the elevator). The jittering is also transmitted via modem to the ground control station (jittering in bank and pitch).

We tried out with different servos and another ArduPilot board and Shield – but without success. Also the IR-sensors were disconnected to ensure that the jittering isn’t induced by the sensors but the sensors seem to be ok. We detected that when only one servo is connected to the board the behaviour is getting better. Power supply is also ok.

Are there any ideas what the problem is?

Thanks very much.

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3D Robotics

Chris Anderson July 9, 2010 at 10:18pm

You might also look at the routing of your serial cable to your Xbee. If it's too close to servo cables RF noise can cause the servos to jitter.
JOHN PIZZICARA July 9, 2010 at 9:54pm

Hi, I had the same problem until I isolated the servo power source from the rest of the system with one of Jordi's 2 channel opto isolators. Tiny surface mount caps are great but don't offer the best in power supply decoupling for relatively large loads like servo motors. If you have a DVM, put it on mv AC scale and place the probes on Vcc and Ground near the servo out connectors, and activate the servos. If you see more that 50 mv AC, there is actually much more at higher frequencies than the meter can see, and isolating the servos may help.

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servo jittering in stabilization mode

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