Start a circular motion to the left. This function returns immediately.

        :param radius_m: The radius of the circle (meters)
        :param velocity: The velocity of the motion (meters/second)
        :return:

def start_circle_left(self, radius_m, velocity=VELOCITY):
        """
        Start a circular motion to the left. This function returns immediately.

        :param radius_m: The radius of the circle (meters)
        :param velocity: The velocity of the motion (meters/second)
        :return:
        """
        circumference = 2 * radius_m * math.pi
        rate = 360.0 * velocity / circumference

        self._set_vel_setpoint(velocity, 0.0, 0.0, -rate)