Map Motor to motor in urdf file

[SchneiderHanna]

Hey,
I have a question.

I have two motors in my urdf file:

And two motors in my fixedwing.py

        motor_params = all_params["motor_params"]
        tau = np.array([1.0] * 2) * motor_params["tau"]
        max_rpm = np.array([1.0] *2) * np.sqrt(
            (motor_params["total_thrust"]) /(2* motor_params["thrust_coef"])
        )
        thrust_coef = np.array([motor_params["thrust_coef"]]*2)
        torque_coef = np.array([motor_params["torque_coef"]]*2)
        thrust_unit = np.array([[1.0, 0.0, 0.0], [1.0, 0.0, 0.0]])
        noise_ratio =  np.array([1.0] * 2) * motor_params["noise_ratio"]
        self.motors = Motors(
            p=self.p,
            physics_period=self.physics_period,
            np_random=self.np_random,
            uav_id=self.Id,
            motor_ids=[0, 1],
            tau=tau,
            max_rpm=max_rpm,
            thrust_coef=thrust_coef,
            torque_coef=torque_coef,
            thrust_unit=thrust_unit,
            noise_ratio=noise_ratio,
        )

But how do I map the two motors from the urdf file to the motor IDs in fixedwing.py

Thanks for your help

[jjshoots]

Hi, thanks for reaching out.

You would need to check what IDs correspond to your new motors using this function that is native to all UAVs: https://github.com/jjshoots/PyFlyt/blob/master/PyFlyt/core/abstractions/base_drone.py#L286

And then update the line that says motor_ids=[0, 1] to those motor IDs.

Then, the setpoint to the motors is now an array of two numbers instead of a single command: https://github.com/jjshoots/PyFlyt/blob/master/PyFlyt/core/drones/fixedwing.py#L264
You can accomplish this using

        self.motors.physics_update(np.array([self.cmd[[5]], self.cmd[[5]]]))

This sends the same power command to both motors.