Servers by jDrones

About rover 4.0 PWM output [Solved]

I’m trying rover4.0. But I found the main pwm output in pixhawk only has 1000 1200 1400 1600 1800 2000us. Even when I slowly pull up throttle the pwm output only change among these values. How can I get the linear PWM output? Can I change parameter in mission planner to solve it?

Where are u seeing these fixed value intervals?

https://ardupilot.org/rover/docs/rover-motor-and-servo-configuration.html

I observed these fixed value by oscilloscope? Is there something wrong with my hardware? I’m using pixhawk V2.

Your hardware is perfectly fine.

What is the value of SERVO3_FUNCTION. Check and let me know.

It should be 70.

Inside Mission planner, you can see in real time as you move the throttle stick on your TX, the PWM value increase in a linear format.

Also, your Oscilloscope ( haven’t used one in 10 years) may not be synchronizing properly with PWN outputs.

Inside Mission planner, when I move the throttle stick ,I can see value increasing in a linear format. At the same time, I measure PWM out in main output. I got the fixed value between 1000us,1200us,1400us,1600us and so on. It isn’t in a linear format.

Simply connect a servo. You can see it will move linearly. Its your Oscilliscope confusing you.

I could be wrong but I don’ think PWM increases in such large intervals. Let Me check at my end.

Thank for this answer. I change my oscilloscope and I find it’s truely my Oscilloscope’s problem!
And thank you again.

1 Like

Ah ha…

Sync it properly also the scope sample rate has to be equal and higher than frequency you are measuring…

oh, I see. Your answer makes me no longer confused。
I can finally move on to the next step.
Rover 4.0 uses steering and throttle to control by default. And I want to use the differential speed of two motors to control the steering. Should I change parameter about frame?I konw that change servo output to throttleleft and throttleright will work in Manual mode. But will it work in auto mode?

I have never built a Rover so not sure. Interestingly, I am putting a giant rover as we speak weighs 250 lbs :wink:

I can check the docs and let you know. Did you read Ardupilot Rover docs?

https://ardupilot.org/rover/docs/auto-mode.html

https://ardupilot.org/rover/docs/rover-motor-and-servo-configuration.html

https://ardupilot.org/rover/docs/steering-mode.html

yes,I have already read these docs.
But I still confused about that problem. Because I think when I change servo Output channel, it will work in RC control model. But if it swtich to auto model, the systerm don’t konw what frame I’m using. It should be change in some parameters about frame.
I think may I have a try that I will know whether it can work to change servo output channel or not. I will tell you the result.

When you flash your flight controller (install firmware) this is where you define what type of vehicle you are designing. Have u done that?

I chose rover4.0.0. Rover4.0 uses steering and throttle to control by defaul. I want to konw, if I use two wheel motor to drive,should I choose a frame again?

No…it should be fine

Hi
I think about this problem again these days. Why will I get the fixed PWM pulse?I only get 1000us, 1200us,1400us,1600us pulse width. What is the ralation between these number and sample rate. Is this a coincidence?
Do you know the reason?
Thank you again.

Why are using an Osciliscope?

Servers by jDrones