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RMP 440 OMNI PWM commanding

Posted: Wed Nov 28, 2012 5:02 pm
by esaad
I have an RMP 440 OMNI. I am trying to command it using PWM signals through connector J7 on the CC as described in section 3.3 of the Hardware Interface Document. I am not using a hobby RC but I am generating the PWM signals using a microcontroller. Would you please provide details of the required PWM signal. Does channel 1 through 4 correspond to each of the 4 wheels? or is channel 1 forward speed, channel 2 yaw rate, etc... Also, please provide the PWM signal specs, i.e. frequency, pulse width, cascading between channels, etc... Please provide any other details that I need to know about for PWM comanding.

Re: RMP 440 OMNI PWM commanding

Posted: Wed Nov 28, 2012 5:44 pm
by Craig
In general, we do not recommend using the RC radio (PWM) interface for robot control when using a microprocessor. As stated in the Hardware Interface document:
Due to the nature of the hobby radio protocol and the lack of deterministic error detection the hobby radio input has the ability to create un-commanded torque by the robot. As an example, if a user set the “safe” state on their spectrum radio to the equivalent of full speed ahead, then if communication was lost with the radio the robot would take off and the user would have a runaway machine.
On the CCU side of the Hobby Radio link we count very heavily on the timing, sequencing, number of inputs, etc. We have made that link compatible with "Spectrum brand 6 channel air receivers". The parameters are extremely tight in order to make sure we have a valid signal set before commands are applied.

For microprocessor control the CAN interface should be used. The Hobby Radio input is intended to be connected to a Spectrum radio not a microprocessor. Hijacking that link and connecting it to a micro is not something I can assist you with.

Re: RMP 440 OMNI PWM commanding

Posted: Wed Nov 28, 2012 6:19 pm
by esaad
Would you please provide details on connectivity to Spektrum 6 channel air receivers. What is the mapping between PWM pins 2-9 on J7 connector and Spektrum channels: Throttle, Aileron, Elevator, Rudder, Gear, Aux1?
Do I need to put the Segway in tractor mode before controlling with the radio? Any other commands are required before commanding with the radio?

Re: RMP 440 OMNI PWM commanding

Posted: Fri Nov 30, 2012 1:03 pm
by sdnalloh
Here is the relevant section from our new RMP Manual which will be released within the next month or so. It does not go into detail about the signals aside from indicating that they are diode or'd together.

I hope this helps.
Hobby Radio.pdf

Re: RMP 440 OMNI PWM commanding

Posted: Sat Dec 01, 2012 12:47 am
by esaad
Great! thanks.