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178 lines
6.1 KiB
178 lines
6.1 KiB
#!/usr/bin/env python |
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from aircraft import Aircraft |
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import util, time, math |
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from math import degrees, radians |
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from rotmat import Vector3, Matrix3 |
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class Motor(object): |
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def __init__(self, angle, clockwise, servo): |
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self.angle = angle # angle in degrees from front |
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self.clockwise = clockwise # clockwise == true, anti-clockwise == false |
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self.servo = servo # what servo output drives this motor |
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def build_motors(frame): |
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'''build a motors list given a frame type''' |
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frame = frame.lower() |
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if frame in [ 'quad', '+', 'x' ]: |
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motors = [ |
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Motor(90, False, 1), |
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Motor(270, False, 2), |
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Motor(0, True, 3), |
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Motor(180, True, 4), |
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] |
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if frame in [ 'x', 'quadx' ]: |
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for i in range(4): |
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motors[i].angle -= 45.0 |
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elif frame in ["y6"]: |
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motors = [ |
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Motor(60, False, 1), |
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Motor(60, True, 7), |
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Motor(180, True, 4), |
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Motor(180, False, 8), |
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Motor(-60, True, 2), |
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Motor(-60, False, 3), |
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] |
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elif frame in ["hexa", "hexa+"]: |
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motors = [ |
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Motor(0, True, 1), |
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Motor(60, False, 4), |
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Motor(120, True, 8), |
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Motor(180, False, 2), |
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Motor(240, True, 3), |
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Motor(300, False, 7), |
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] |
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elif frame in ["hexax"]: |
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motors = [ |
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Motor(30, False, 7), |
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Motor(90, True, 1), |
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Motor(150, False, 4), |
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Motor(210, True, 8), |
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Motor(270, False, 2), |
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Motor(330, True, 3), |
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] |
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elif frame in ["octa", "octa+", "octax" ]: |
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motors = [ |
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Motor(0, True, 1), |
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Motor(180, True, 2), |
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Motor(45, False, 3), |
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Motor(135, False, 4), |
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Motor(-45, False, 7), |
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Motor(-135, False, 8), |
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Motor(270, True, 10), |
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Motor(90, True, 11), |
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] |
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if frame == 'octax': |
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for i in range(8): |
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motors[i].angle += 22.5 |
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else: |
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raise RuntimeError("Unknown multicopter frame type '%s'" % frame) |
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return motors |
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class MultiCopter(Aircraft): |
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'''a MultiCopter''' |
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def __init__(self, frame='+', |
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hover_throttle=0.37, |
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terminal_velocity=30.0, |
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frame_height=0.1, |
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mass=1.0): |
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Aircraft.__init__(self) |
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self.motors = build_motors(frame) |
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self.motor_speed = [ 0.0 ] * len(self.motors) |
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self.mass = mass # Kg |
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self.hover_throttle = hover_throttle |
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self.terminal_velocity = terminal_velocity |
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self.terminal_rotation_rate = 4*radians(360.0) |
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self.frame_height = frame_height |
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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) / (len(self.motors) * 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, len(self.motors)): |
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servo = servos[self.motors[i].servo-1] |
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if servo <= 0.0: |
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self.motor_speed[i] = 0 |
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else: |
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self.motor_speed[i] = servo |
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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 rad/s/s, in body frame |
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rot_accel = Vector3(0,0,0) |
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thrust = 0.0 |
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for i in range(len(self.motors)): |
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rot_accel.x += -radians(5000.0) * math.sin(radians(self.motors[i].angle)) * m[i] |
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rot_accel.y += radians(5000.0) * math.cos(radians(self.motors[i].angle)) * m[i] |
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if self.motors[i].clockwise: |
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rot_accel.z -= m[i] * radians(400.0) |
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else: |
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rot_accel.z += m[i] * radians(400.0) |
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thrust += m[i] * self.thrust_scale # newtons |
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# rotational air resistance |
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rot_accel.x -= self.gyro.x * radians(5000.0) / self.terminal_rotation_rate |
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rot_accel.y -= self.gyro.y * radians(5000.0) / self.terminal_rotation_rate |
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rot_accel.z -= self.gyro.z * radians(400.0) / self.terminal_rotation_rate |
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# update rotational rates in body frame |
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self.gyro += rot_accel * delta_time |
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# update attitude |
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self.dcm.rotate(self.gyro * delta_time) |
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self.dcm.normalize() |
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# air resistance |
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air_resistance = - self.velocity * (self.gravity/self.terminal_velocity) |
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accel_body = Vector3(0, 0, -thrust / self.mass) |
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accel_earth = self.dcm * accel_body |
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accel_earth += Vector3(0, 0, self.gravity) |
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accel_earth += air_resistance |
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# add in some wind (turn force into accel by dividing by mass). |
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accel_earth += self.wind.drag(self.velocity) / self.mass |
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# if we're on the ground, then our vertical acceleration is limited |
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# to zero. This effectively adds the force of the ground on the aircraft |
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if self.on_ground() and accel_earth.z > 0: |
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accel_earth.z = 0 |
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# work out acceleration as seen by the accelerometers. It sees the kinematic |
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# acceleration (ie. real movement), plus gravity |
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self.accel_body = self.dcm.transposed() * (accel_earth + Vector3(0, 0, -self.gravity)) |
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# new velocity vector |
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self.velocity += accel_earth * delta_time |
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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.on_ground(): |
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if not self.on_ground(old_position): |
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print("Hit ground at %f m/s" % (self.velocity.z)) |
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self.velocity = Vector3(0, 0, 0) |
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# zero roll/pitch, but keep yaw |
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(r, p, y) = self.dcm.to_euler() |
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self.dcm.from_euler(0, 0, y) |
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self.position = 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(delta_time)
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