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122 lines
4.4 KiB
122 lines
4.4 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, sin, cos |
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from rotmat import Vector3, Matrix3 |
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class HeliCopter(Aircraft): |
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'''a HeliCopter simulator''' |
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def __init__(self, frame='+', |
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hover_throttle=0.65, |
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terminal_velocity=40.0, |
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frame_height=0.1, |
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hover_lean=8.0, |
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yaw_zero=0.1, |
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rotor_rot_accel=radians(20), |
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mass=2.13): |
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Aircraft.__init__(self) |
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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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self.last_time = time.time() |
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self.roll_rate_max = radians(1400) |
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self.pitch_rate_max = radians(1400) |
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self.yaw_rate_max = radians(1400) |
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self.rsc_setpoint = 0.8 |
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self.thrust_scale = (self.mass * self.gravity) / self.hover_throttle |
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self.rotor_rot_accel=rotor_rot_accel |
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# calculate lateral thrust ratio for tail rotor |
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self.tail_thrust_scale = sin(radians(hover_lean)) * self.thrust_scale / yaw_zero |
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def update(self, servos): |
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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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# get swash proportions (these are from 0 to 1) |
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swash1 = servos[0] |
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swash2 = servos[1] |
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swash3 = servos[2] |
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tail_rotor = servos[3] |
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rsc = servos[7] |
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# get total thrust from 0 to 1 |
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thrust = (rsc/self.rsc_setpoint)*(swash1+swash2+swash3)/3.0 |
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# very simplistic mapping to body euler rates |
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roll_rate = swash1 - swash2 |
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pitch_rate = (swash1 + swash2)/2.0 - swash3 |
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yaw_rate = tail_rotor - 0.5 |
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#print(swash1, swash2, swash3, roll_rate, pitch_rate, yaw_rate, thrust, rsc) |
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rsc_scale = rsc/self.rsc_setpoint |
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roll_rate *= rsc_scale |
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pitch_rate *= rsc_scale |
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yaw_rate *= rsc_scale |
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rot_accel = Vector3(roll_rate*self.roll_rate_max, |
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pitch_rate*self.pitch_rate_max, |
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yaw_rate*self.yaw_rate_max) |
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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(5000.0) / self.terminal_rotation_rate |
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rot_accel.z += (rsc_scale+thrust) * self.rotor_rot_accel |
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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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thrust *= self.thrust_scale |
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accel_body = Vector3(0, yaw_rate * rsc_scale * self.tail_thrust_scale, -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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# 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()
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