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88 lines
3.0 KiB
88 lines
3.0 KiB
#!/usr/bin/env python |
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from aircraft import Aircraft |
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import euclid, util, time |
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class QuadCopter(Aircraft): |
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'''a QuadCopter''' |
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def __init__(self): |
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Aircraft.__init__(self) |
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self.motor_speed = [ 0.0, 0.0, 0.0, 0.0 ] |
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self.mass = 1.0 # Kg |
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self.hover_throttle = 0.37 |
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self.terminal_velocity = 30.0 |
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self.frame_height = 0.1 |
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# scaling from total motor power to Newtons. Allows the copter |
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# to hover against gravity when each motor is at hover_throttle |
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self.thrust_scale = (self.mass * self.gravity) / (4.0 * self.hover_throttle) |
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self.last_time = time.time() |
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def update(self, servos): |
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for i in range(0, 4): |
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if servos[i] <= 0.0: |
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self.motor_speed[i] = 0 |
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else: |
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self.motor_speed[i] = servos[i] |
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m = self.motor_speed |
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# how much time has passed? |
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t = time.time() |
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delta_time = t - self.last_time |
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self.last_time = t |
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# rotational acceleration, in degrees/s/s |
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roll_accel = (m[1] - m[0]) * 5000.0 |
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pitch_accel = (m[2] - m[3]) * 5000.0 |
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yaw_accel = -((m[2]+m[3]) - (m[0]+m[1])) * 400.0 |
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# update rotational rates |
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self.roll_rate += roll_accel * delta_time |
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self.pitch_rate += pitch_accel * delta_time |
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self.yaw_rate += yaw_accel * delta_time |
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# update rotation |
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self.roll += self.roll_rate * delta_time |
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self.pitch += self.pitch_rate * delta_time |
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self.yaw += self.yaw_rate * delta_time |
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# air resistance |
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air_resistance = - self.velocity * (self.gravity/self.terminal_velocity) |
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# normalise rotations |
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self.normalise() |
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thrust = (m[0] + m[1] + m[2] + m[3]) * self.thrust_scale # Newtons |
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accel = thrust / self.mass |
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accel3D = util.RPY_to_XYZ(self.roll, self.pitch, self.yaw, accel) |
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accel3D += euclid.Vector3(0, 0, -self.gravity) |
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accel3D += air_resistance |
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# new velocity vector |
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self.velocity += accel3D * delta_time |
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self.accel = accel3D |
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# new position vector |
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old_position = self.position.copy() |
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self.position += self.velocity * delta_time |
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# constrain height to the ground |
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if self.position.z + self.home_altitude < self.ground_level + self.frame_height: |
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if old_position.z + self.home_altitude > self.ground_level + self.frame_height: |
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print("Hit ground at %f m/s" % (-self.velocity.z)) |
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self.velocity = euclid.Vector3(0, 0, 0) |
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self.roll_rate = 0 |
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self.pitch_rate = 0 |
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self.yaw_rate = 0 |
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self.roll = 0 |
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self.pitch = 0 |
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self.accel = euclid.Vector3(0, 0, 0) |
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self.position = euclid.Vector3(self.position.x, self.position.y, |
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self.ground_level + self.frame_height - self.home_altitude) |
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# update lat/lon/altitude |
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self.update_position()
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