Camera \ EMF problems...

[zachriggle]

I have a very peculiar situation, involving the camera servo's dancing when the Fisher-Price motor turns on.

We are using a Fisher-price motor for a ball launcher mechanism, mounted on a turret-style (pan only, no tilting mechanism) plate. The camera is also mounted on this plate.

With the servo's set to center (to rule out programming as a potential source of the problem), and the camera unplugged, the servo's go absolutely NUTS as soon as the Fisher-Price motor turns on. I mean disco dancing on steroids. The FP motor is connected to a Victor, as required, and is controlled via a PWM cable, as required.

However, when the FP motor is given direct voltage from a second battery... there is no such effect. Something in the electrical system is allowing voltage to creep and spike on some portion of the PWM cables, bet it the signal or +7.2V wire, I don't know.

None of the other PWM-controlled devices seem to be effected. The power wires for the FP motor run near the camera... but I doubt that *that* has anything to do with it. The wires from the camera also run between the battery leads, between BOTH drive (CIM) motors (3 cm proximity) under a window motor (2 cm proximity), and is equally centered between the victor for the FP motor and the victor for the Van Door motor... and with ALL of the other motors on, this phenomena is not replicated. We are using 12ga (10ga?) wire for all motors.

Additionally, the camera's terminal interface seems to work just fine, because Kevin's code can lock onto targets for short periods of time with the FP motors on, until the servo's craziness causes the camera to lose track of its target... until it's reaquired.

Also, can anyone else pick up voltage between any parts of their chassis and the common ground? We're getting between 0 and 3.2v readings. We physically removed the camera from the chassis to remove that as a reason for the servo weirdness, but it's still something we don't like. There is conductance between the casing of the FP motor and the plate that the entire firing mechanism rests on. Does the FP motor create a magnetic field so large that it would treat a 0.75cm rubber spacer more like a resistor than a block to conductance (the motor is not physically touching the chassis, but it conducts to the top, rotary plate. The top, rotary plate does not show conductance when tested against other parts of the chassis, pecularly).

Can anyone explain this phenomena? All that we can think of is that the FP motor is either generating a HUGE EMF, or there is some kind of back-feed down the PWM signal cable attached to the Victor controller.