using pixhawk4 to control a skid-steer rover

ArduRover
1

Hi dears
I am working with skid-steer rover. but i am using one controller board for the right motor and one for the left.
each controller has an input for the throttle value as analog input between 0 and 5V
and one relay input for the brake. and one input for the FWD/REV direction.
the controller used is : KAC-8080N
I want to use an ardupilot in this application example: pixhawk4
if i use the settings indicated in the wiki for working with skid-steer:

2

You many be able to use a module like this do help with he signal conversion.

It has additional pwm to relay outputs that may work for the switched signals.

4

if i want to use a joystick to contol each side of motors without the use of REV/FWD switches. should i use brushed with relay or brushed bipolar as the MOT_PWM_TYPE?
the wiki states:

  • “Brushed With Relay” motor drivers accept a duty cycle to control the speed and also have a separate pin used to control direction
  • “Brushed BiPolar” motor drivers accept a duty cycle where 0% duty cycle means full speed in one direction, 100% duty cycle is full speed in the other direction and 50% duty cycle is stopped.
    ???
5

This depends on the type of motor driver you physically have.

6

it is brushed motor.
the driver accept the throttle signal analog (0-5V)
and a switch signal for the direction (REV/FWD)
i have solved the problem of connecting the PWM signal from the servo output to the driver by using a pwm to analog converter.
now i want to cancel the use of the REV/FWD pin and control the direction from the joystick giving the throttle (0% to full reverse, 50% to stopped, and 100% to full forwards) .
for that i am asking if brushed bipolar can perform this task.
but in page 22 of the controller datasheet there is a statement:
KAC controller only can work with F-N-R control. Customers must use forward switch and reversing switch at the same time to change the motor direction.
so i think it is preferable to use brushed with relay . is that right?
how to configure the stick to do what i stated to control the direction ?

7

the driver used KAC-8080N

8

I look at this and I wonder why you aren’t using CAN to drive the controller? Does the controller accept inputs (i.e. commanded velocities or commanded duty cycles) over the CAN bus? If so then I’d recommend you spend some effort to see if you can avoid having to implement the complicated converter circuitry (to take pixhawk4 pwm out and convert into a 5v analog signal) (plus you’ll also have to figure out forward/reverse signaling as well which ain’t gonna be easy). I’d recommend connecting CANH and CANL to the pixhawk’s CANH and CANL, then, wrestling with the various CAN configurations to get that working. This also greatly minimizes the risk of ground loops. (Do you know what ground loops are?)

9

As I wrote before, it depends of the physical motor driver you are using and not of some settings of the FC.
Your specific motor controller has not the functionallity to do what you want.
It needs 0 to 5V for throttle and switches for fwd and rev.
This due to the normal function of this controller in manuall controlled vehicles like golfcars etc.
If you want to have the F-N-R functionallyty you have to built your own small adapter maybe on base of an arduino which is converting the fullrange pwm output of the FC to the signals the Motor controller needs.
@Christopher_Milner , this motor controller is not using the CAN for controlling. The CAN interface is just for monitoring