mirror of https://github.com/ArduPilot/ardupilot
310 lines
11 KiB
Plaintext
310 lines
11 KiB
Plaintext
// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
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/*
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* servos.pde - code to move pitch and yaw servos to attain a target heading or pitch
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*/
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// init_servos - initialises the servos
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static void init_servos()
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{
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// setup antenna control PWM channels
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channel_yaw.set_angle(g.yaw_range * 100/2); // yaw range is +/- (YAW_RANGE parameter/2) converted to centi-degrees
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channel_pitch.set_angle(g.pitch_range * 100/2); // pitch range is +/- (PITCH_RANGE parameter/2) converted to centi-degrees
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// move servos to mid position
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channel_yaw.output_trim();
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channel_pitch.output_trim();
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// initialise output to servos
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channel_yaw.calc_pwm();
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channel_pitch.calc_pwm();
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}
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/**
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update the pitch (elevation) servo. The aim is to drive the boards ahrs pitch to the
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requested pitch, so the board (and therefore the antenna) will be pointing at the target
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*/
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static void update_pitch_servo(float pitch)
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{
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switch ((enum ServoType)g.servo_type.get()) {
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case SERVO_TYPE_ONOFF:
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update_pitch_onoff_servo(pitch);
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break;
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case SERVO_TYPE_POSITION:
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default:
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update_pitch_position_servo(pitch);
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break;
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}
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// convert servo_out to radio_out and send to servo
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channel_pitch.calc_pwm();
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channel_pitch.output();
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}
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/**
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update the pitch (elevation) servo. The aim is to drive the boards ahrs pitch to the
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requested pitch, so the board (and therefore the antenna) will be pointing at the target
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*/
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static void update_pitch_position_servo(float pitch)
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{
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// degrees(ahrs.pitch) is -90 to 90, where 0 is horizontal
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// pitch argument is -90 to 90, where 0 is horizontal
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// servo_out is in 100ths of a degree
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float ahrs_pitch = ahrs.pitch_sensor*0.01f;
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int32_t angle_err = -(ahrs_pitch - pitch) * 100.0;
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int32_t pitch_limit_cd = g.pitch_range*100/2;
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// Need to configure your servo so that increasing servo_out causes increase in pitch/elevation (ie pointing higher into the sky,
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// above the horizon. On my antenna tracker this requires the pitch/elevation servo to be reversed
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// param set RC2_REV -1
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//
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// The pitch servo (RC channel 2) is configured for servo_out of -9000-0-9000 servo_out,
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// which will drive the servo from RC2_MIN to RC2_MAX usec pulse width.
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// Therefore, you must set RC2_MIN and RC2_MAX so that your servo drives the antenna altitude between -90 to 90 exactly
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// To drive my HS-645MG servos through their full 180 degrees of rotational range, I have to set:
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// param set RC2_MAX 2540
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// param set RC2_MIN 640
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//
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// You will also need to tune the pitch PID to suit your antenna and servos. I use:
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// PITCH2SRV_P 0.100000
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// PITCH2SRV_I 0.020000
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// PITCH2SRV_D 0.000000
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// PITCH2SRV_IMAX 4000.000000
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// calculate new servo position
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int32_t new_servo_out = channel_pitch.servo_out + g.pidPitch2Srv.get_pid(angle_err);
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// initialise limit flags
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servo_limit.pitch_lower = false;
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servo_limit.pitch_upper = false;
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// rate limit pitch servo
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if (g.pitch_slew_time > 0.02f) {
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uint16_t max_change = 0.02f * (pitch_limit_cd) / g.pitch_slew_time;
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if (max_change < 1) {
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max_change = 1;
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}
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if (new_servo_out <= channel_pitch.servo_out - max_change) {
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new_servo_out = channel_pitch.servo_out - max_change;
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servo_limit.pitch_lower = true;
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}
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if (new_servo_out >= channel_pitch.servo_out + max_change) {
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new_servo_out = channel_pitch.servo_out + max_change;
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servo_limit.pitch_upper = true;
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}
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}
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channel_pitch.servo_out = new_servo_out;
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// position limit pitch servo
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if (channel_pitch.servo_out <= -pitch_limit_cd) {
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channel_pitch.servo_out = -pitch_limit_cd;
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servo_limit.pitch_lower = true;
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}
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if (channel_pitch.servo_out >= pitch_limit_cd) {
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channel_pitch.servo_out = pitch_limit_cd;
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servo_limit.pitch_upper = true;
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}
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}
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/**
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update the pitch (elevation) servo. The aim is to drive the boards ahrs pitch to the
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requested pitch, so the board (and therefore the antenna) will be pointing at the target
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*/
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static void update_pitch_onoff_servo(float pitch)
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{
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// degrees(ahrs.pitch) is -90 to 90, where 0 is horizontal
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// pitch argument is -90 to 90, where 0 is horizontal
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// servo_out is in 100ths of a degree
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float ahrs_pitch = degrees(ahrs.pitch);
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float err = ahrs_pitch - pitch;
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float acceptable_error = g.onoff_pitch_rate * g.onoff_pitch_mintime;
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if (fabsf(err) < acceptable_error) {
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channel_pitch.servo_out = 0;
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} else if (err > 0) {
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// positive error means we are pointing too high, so push the
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// servo down
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channel_pitch.servo_out = -9000;
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} else {
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// negative error means we are pointing too low, so push the
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// servo up
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channel_pitch.servo_out = 9000;
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}
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}
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/**
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update the yaw (azimuth) servo.
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*/
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static void update_yaw_servo(float yaw)
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{
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switch ((enum ServoType)g.servo_type.get()) {
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case SERVO_TYPE_ONOFF:
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update_yaw_onoff_servo(yaw);
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break;
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case SERVO_TYPE_POSITION:
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default:
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update_yaw_position_servo(yaw);
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break;
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}
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// convert servo_out to radio_out and send to servo
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channel_yaw.calc_pwm();
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channel_yaw.output();
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}
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/**
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update the yaw (azimuth) servo. The aim is to drive the boards ahrs
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yaw to the requested yaw, so the board (and therefore the antenna)
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will be pointing at the target
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*/
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static void update_yaw_position_servo(float yaw)
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{
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int32_t ahrs_yaw_cd = wrap_180_cd(ahrs.yaw_sensor);
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int32_t yaw_cd = wrap_180_cd(yaw*100);
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int32_t yaw_limit_cd = g.yaw_range*100/2;
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const int16_t margin = 500; // 5 degrees slop
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// Antenna as Ballerina. Use with antenna that do not have continuously rotating servos, ie at some point in rotation
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// the servo limits are reached and the servo has to slew 360 degrees to the 'other side' to keep tracking.
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//
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// This algorithm accounts for the fact that the antenna mount may not be aligned with North
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// (in fact, any alignment is permissable), and that the alignment may change (possibly rapidly) over time
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// (as when the antenna is mounted on a moving, turning vehicle)
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// When the servo is being forced beyond its limits, it rapidly slews to the 'other side' then normal tracking takes over.
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//
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// With my antenna mount, large pwm output drives the antenna anticlockise, so need:
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// param set RC1_REV -1
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// to reverse the servo. Yours may be different
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//
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// You MUST set RC1_MIN and RC1_MAX so that your servo drives the antenna azimuth from -180 to 180 relative
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// to the mount.
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// To drive my HS-645MG servos through their full 180 degrees of rotational range and therefore the
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// antenna through a full 360 degrees, I have to set:
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// param set RC1_MAX 2380
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// param set RC1_MIN 680
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// According to the specs at https://www.servocity.com/html/hs-645mg_ultra_torque.html,
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// that should be 600 through 2400, but the azimuth gearing in my antenna pointer is not exactly 2:1
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int32_t angle_err = wrap_180_cd(ahrs_yaw_cd - yaw_cd);
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/*
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a positive error means that we need to rotate counter-clockwise
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a negative error means that we need to rotate clockwise
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Use our current yawspeed to determine if we are moving in the
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right direction
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*/
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static int8_t slew_dir;
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static uint32_t slew_start_ms;
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int8_t new_slew_dir = slew_dir;
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// get earth frame z-axis rotation rate in radians
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Vector3f earth_rotation = ahrs.get_gyro() * ahrs.get_dcm_matrix();
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bool making_progress;
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if (slew_dir != 0) {
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making_progress = (-slew_dir * earth_rotation.z >= 0);
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} else {
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making_progress = (angle_err * earth_rotation.z >= 0);
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}
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// handle hitting servo limits
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if (abs(channel_yaw.servo_out) == 18000 &&
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labs(angle_err) > margin &&
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making_progress &&
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hal.scheduler->millis() - slew_start_ms > g.min_reverse_time*1000) {
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// we are at the limit of the servo and are not moving in the
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// right direction, so slew the other way
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new_slew_dir = -channel_yaw.servo_out / 18000;
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slew_start_ms = hal.scheduler->millis();
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}
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/*
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stop slewing and revert to normal control when normal control
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should move us in the right direction
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*/
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if (slew_dir * angle_err < -margin) {
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new_slew_dir = 0;
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}
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if (new_slew_dir != slew_dir) {
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gcs_send_text_fmt(PSTR("SLEW: %d/%d err=%ld servo=%ld ez=%.3f"),
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(int)slew_dir, (int)new_slew_dir,
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(long)angle_err,
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(long)channel_yaw.servo_out,
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degrees(ahrs.get_gyro().z));
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}
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slew_dir = new_slew_dir;
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// initialise limit flags
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servo_limit.yaw_lower = false;
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servo_limit.yaw_upper = false;
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int16_t new_servo_out;
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if (slew_dir != 0) {
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new_servo_out = slew_dir * 18000;
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g.pidYaw2Srv.reset_I();
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} else {
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float servo_change = g.pidYaw2Srv.get_pid(angle_err);
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servo_change = constrain_float(servo_change, -18000, 18000);
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new_servo_out = constrain_float(channel_yaw.servo_out - servo_change, -18000, 18000);
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}
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// rate limit yaw servo
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if (g.yaw_slew_time > 0.02f) {
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uint16_t max_change = 0.02f * yaw_limit_cd / g.yaw_slew_time;
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if (max_change < 1) {
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max_change = 1;
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}
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if (new_servo_out <= channel_yaw.servo_out - max_change) {
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new_servo_out = channel_yaw.servo_out - max_change;
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servo_limit.yaw_lower = true;
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}
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if (new_servo_out >= channel_yaw.servo_out + max_change) {
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new_servo_out = channel_yaw.servo_out + max_change;
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servo_limit.yaw_upper = true;
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}
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}
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channel_yaw.servo_out = new_servo_out;
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// position limit pitch servo
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if (channel_yaw.servo_out <= -yaw_limit_cd) {
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channel_yaw.servo_out = -yaw_limit_cd;
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servo_limit.yaw_lower = true;
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}
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if (channel_yaw.servo_out >= yaw_limit_cd) {
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channel_yaw.servo_out = yaw_limit_cd;
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servo_limit.yaw_upper = true;
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}
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}
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/**
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update the yaw (azimuth) servo. The aim is to drive the boards ahrs
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yaw to the requested yaw, so the board (and therefore the antenna)
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will be pointing at the target
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*/
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static void update_yaw_onoff_servo(float yaw)
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{
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int32_t ahrs_yaw_cd = wrap_180_cd(ahrs.yaw_sensor);
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int32_t yaw_cd = wrap_180_cd(yaw*100);
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int32_t err_cd = wrap_180_cd(ahrs_yaw_cd - yaw_cd);
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float err = err_cd * 0.01f;
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float acceptable_error = g.onoff_yaw_rate * g.onoff_yaw_mintime;
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if (fabsf(err) < acceptable_error) {
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channel_yaw.servo_out = 0;
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} else if (err > 0) {
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// positive error means we are clockwise of the target, so
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// move anti-clockwise
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channel_yaw.servo_out = -18000;
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} else {
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// negative error means we are anti-clockwise of the target, so
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// move clockwise
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channel_yaw.servo_out = 18000;
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}
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}
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