EMI/transient suppression
Our team has experienced some difficulties when using the Banebots Gearmotor together with the vision camera pan/tilt unit. When the motor is activated, the servos in the camera assembly twitch uncontrollably (even when instructed to stay still by the RC). Our wiring is routed separately. Through testing, we came to the conclusion that the Gearmotor is coupling EMI into its case, which is ultimately also connected through the chassis to metal parts that run parallel to the PWM wiring. As the chassis is electrically isolated (per other rules), interference is easily coupled into it, and then into the PWM wiring. We found that the addition of a .01uF ceramic disc capacitor (Jameco no. 15229) from the case to each input lead of the motor eliminated the problem. Is this legal?
<R63> states that:
By the same token as current monitoring, the capacitors have no effect on the operation of the motor. The connection to the chassis is also high-impedance, since the capacitors will only shunt very high frequency transients. Essentially, the capacitors have no effect on the motor's power connections - its effect is on undesired currents on the motor and robot chassis.[Custom circuits can not] directly alter the power pathways between the battery, fuse blocks, speed controllers,
relays, or motors. Custom high impedance voltage monitoring or low impedance current
monitoring circuitry connected to the ROBOT’S electrical system is
acceptable, because the
effect on the ROBOT outputs should be inconsequential.
[Custom circuits can not] Directly affect any output devices on the ROBOT, such as by providing power directly to a
motor, supplying a PWM signal to a speed controller or supplying a control signal to a relay
module.
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