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Using PWM to control an actuator


(Todd Sparkes) #1

Hello,
Could somebody tell me (in very basic language) how I can open and close an actuator using a PWM signal from pixhawk? Can I operate the actuator from a separate power supply? How do I configure the hand controller to operate the open close functions? A simple drawing would be the easiest way for me to understand the circuit required.

Thanks


(Jacob) #2

If your actuator is a servo, then you can connect the servo to the Pixhawk. If you are using a large servo, then you can use a separate power supply, and connect the PWM signal pin to the Pixhawk, and the power wires to a separate power supply. The ground of that supply must be wired to the ground of the Pixhawk, though.

In ArduSub3.5, you can configure joystick buttons for setting servo outputs to preset open/close values with the servo_n_min and servo_n_max button functions.


(Rusty) #3

Hi Todd,

If your actuator is a brushed motor, like many off-the-shelf grabbers, then you’d require a brushed speed controller that responds to a PWM signal. If that’s the case I can point you towards some options, such as those available from Pololu.com.

-Rusty


(Todd Sparkes) #4

Rusty,
If you look at the pics this is the way I was leaning for an actuator. Easy installation and should be pretty easy to waterproof. These are 12Vdc approx 5amp models. Connecting the rod to a jaw mechanism should be only a pin. Would a brushed speed controller that responds to a PWM signal be able to control this type of actuator?


(Rusty) #5

Hi Todd,

Yes, a brush motor controller with PWM input would be perfect for this.

-Rusty


(Todd Sparkes) #6

Thank you Rusty for the response. Can you recommend a controller board? Also where on the pixhawk would this be plugged into the unit?

Regards
Todd


(Rusty) #7

Hi Todd,

A controller like this would probably work well:

You would have to connect the PWM to one of the auxiliary channels on the Pixhawk. @jwalser could describe that and the button setup in more detail.

-Rusty