ardupilot/APMrover2/mode.cpp

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#include "mode.h"
#include "Rover.h"
Mode::Mode() :
ahrs(rover.ahrs),
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g(rover.g),
g2(rover.g2),
channel_steer(rover.channel_steer),
channel_throttle(rover.channel_throttle),
channel_lateral(rover.channel_lateral),
mission(rover.mission),
attitude_control(rover.g2.attitude_control)
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{ }
void Mode::exit()
{
// call sub-classes exit
_exit();
}
bool Mode::enter()
{
const bool ignore_checks = !hal.util->get_soft_armed(); // allow switching to any mode if disarmed. We rely on the arming check to perform
if (!ignore_checks) {
// get EKF filter status
nav_filter_status filt_status;
rover.ahrs.get_filter_status(filt_status);
// check position estimate. requires origin and at least one horizontal position flag to be true
Location origin;
const bool position_ok = ahrs.get_origin(origin) &&
(filt_status.flags.horiz_pos_abs || filt_status.flags.pred_horiz_pos_abs ||
filt_status.flags.horiz_pos_rel || filt_status.flags.pred_horiz_pos_rel);
if (requires_position() && !position_ok) {
return false;
}
// check velocity estimate (if we have position estimate, we must have velocity estimate)
if (requires_velocity() && !position_ok && !filt_status.flags.horiz_vel) {
return false;
}
}
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return _enter();
}
// decode pilot steering and throttle inputs and return in steer_out and throttle_out arguments
// steering_out is in the range -4500 ~ +4500 with positive numbers meaning rotate clockwise
// throttle_out is in the range -100 ~ +100
void Mode::get_pilot_input(float &steering_out, float &throttle_out)
{
// no RC input means no throttle and centered steering
if (rover.failsafe.bits & FAILSAFE_EVENT_THROTTLE) {
steering_out = 0;
throttle_out = 0;
return;
}
// apply RC skid steer mixing
switch ((enum pilot_steer_type_t)rover.g.pilot_steer_type.get())
{
case PILOT_STEER_TYPE_DEFAULT:
case PILOT_STEER_TYPE_DIR_REVERSED_WHEN_REVERSING:
default: {
// by default regular and skid-steering vehicles reverse their rotation direction when backing up
throttle_out = rover.channel_throttle->get_control_in();
const float steering_dir = is_negative(throttle_out) ? -1 : 1;
steering_out = steering_dir * rover.channel_steer->get_control_in();
break;
}
case PILOT_STEER_TYPE_TWO_PADDLES: {
// convert the two radio_in values from skid steering values
// left paddle from steering input channel, right paddle from throttle input channel
// steering = left-paddle - right-paddle
// throttle = average(left-paddle, right-paddle)
const float left_paddle = rover.channel_steer->norm_input();
const float right_paddle = rover.channel_throttle->norm_input();
throttle_out = 0.5f * (left_paddle + right_paddle) * 100.0f;
steering_out = (left_paddle - right_paddle) * 0.5f * 4500.0f;
break;
}
case PILOT_STEER_TYPE_DIR_UNCHANGED_WHEN_REVERSING: {
throttle_out = rover.channel_throttle->get_control_in();
steering_out = rover.channel_steer->get_control_in();
break;
}
}
}
// decode pilot steering and throttle inputs and return in steer_out and throttle_out arguments
// steering_out is in the range -4500 ~ +4500 with positive numbers meaning rotate clockwise
// throttle_out is in the range -100 ~ +100
void Mode::get_pilot_desired_steering_and_throttle(float &steering_out, float &throttle_out)
{
// do basic conversion
get_pilot_input(steering_out, throttle_out);
// check for special case of input and output throttle being in opposite directions
float throttle_out_limited = g2.motors.get_slew_limited_throttle(throttle_out, rover.G_Dt);
if ((is_negative(throttle_out) != is_negative(throttle_out_limited)) &&
((g.pilot_steer_type == PILOT_STEER_TYPE_DEFAULT) ||
(g.pilot_steer_type == PILOT_STEER_TYPE_DIR_REVERSED_WHEN_REVERSING))) {
steering_out *= -1;
}
throttle_out = throttle_out_limited;
}
// decode pilot steering and return steering_out and speed_out (in m/s)
void Mode::get_pilot_desired_steering_and_speed(float &steering_out, float &speed_out)
{
float desired_throttle;
get_pilot_input(steering_out, desired_throttle);
speed_out = desired_throttle * 0.01f * calc_speed_max(g.speed_cruise, g.throttle_cruise * 0.01f);
// check for special case of input and output throttle being in opposite directions
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float speed_out_limited = g2.attitude_control.get_desired_speed_accel_limited(speed_out, rover.G_Dt);
if ((is_negative(speed_out) != is_negative(speed_out_limited)) &&
((g.pilot_steer_type == PILOT_STEER_TYPE_DEFAULT) ||
(g.pilot_steer_type == PILOT_STEER_TYPE_DIR_REVERSED_WHEN_REVERSING))) {
steering_out *= -1;
}
speed_out = speed_out_limited;
}
// decode pilot lateral movement input and return in lateral_out argument
void Mode::get_pilot_desired_lateral(float &lateral_out)
{
// no RC input means no lateral input
if (rover.failsafe.bits & FAILSAFE_EVENT_THROTTLE) {
lateral_out = 0;
return;
}
// get pilot lateral input
lateral_out = rover.channel_lateral->get_control_in();
}
// set desired location
void Mode::set_desired_location(const struct Location& destination, float next_leg_bearing_cd)
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{
// set origin to last destination if waypoint controller active
if ((AP_HAL::millis() - last_steer_to_wp_ms < 100) && _reached_destination) {
_origin = _destination;
} else {
// otherwise use reasonable stopping point
calc_stopping_location(_origin);
}
_destination = destination;
// initialise distance
_distance_to_destination = get_distance(_origin, _destination);
_reached_destination = false;
// set final desired speed
_desired_speed_final = 0.0f;
if (!is_equal(next_leg_bearing_cd, MODE_NEXT_HEADING_UNKNOWN)) {
const float curr_leg_bearing_cd = get_bearing_cd(_origin, _destination);
const float turn_angle_cd = wrap_180_cd(next_leg_bearing_cd - curr_leg_bearing_cd);
if (is_zero(turn_angle_cd)) {
// if not turning can continue at full speed
_desired_speed_final = _desired_speed;
} else if (rover.use_pivot_steering_at_next_WP(turn_angle_cd)) {
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// pivoting so we will stop
_desired_speed_final = 0.0f;
} else {
// calculate maximum speed that keeps overshoot within bounds
const float radius_m = fabsf(g.waypoint_overshoot / (cosf(radians(turn_angle_cd * 0.01f)) - 1.0f));
_desired_speed_final = MIN(_desired_speed, safe_sqrt(g.turn_max_g * GRAVITY_MSS * radius_m));
}
}
}
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// set desired location as an offset from the EKF origin in NED frame
bool Mode::set_desired_location_NED(const Vector3f& destination, float next_leg_bearing_cd)
{
Location destination_ned;
// initialise destination to ekf origin
if (!ahrs.get_origin(destination_ned)) {
return false;
}
// apply offset
location_offset(destination_ned, destination.x, destination.y);
set_desired_location(destination_ned, next_leg_bearing_cd);
return true;
}
// set desired heading and speed
void Mode::set_desired_heading_and_speed(float yaw_angle_cd, float target_speed)
{
// handle initialisation
_reached_destination = false;
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// record targets
_desired_yaw_cd = yaw_angle_cd;
_desired_speed = target_speed;
}
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// get default speed for this mode (held in (CRUISE_SPEED, WP_SPEED or RTL_SPEED)
float Mode::get_speed_default(bool rtl) const
{
if (rtl && is_positive(g2.rtl_speed)) {
return g2.rtl_speed;
} else if (is_positive(g2.wp_speed)) {
return g2.wp_speed;
} else {
return g.speed_cruise;
}
}
// restore desired speed to default from parameter values (CRUISE_SPEED or WP_SPEED)
void Mode::set_desired_speed_to_default(bool rtl)
{
_desired_speed = get_speed_default(rtl);
}
// set desired speed in m/s
bool Mode::set_desired_speed(float speed)
{
if (!is_negative(speed)) {
_desired_speed = speed;
return true;
}
return false;
}
void Mode::calc_throttle(float target_speed, bool nudge_allowed, bool avoidance_enabled)
{
// add in speed nudging
if (nudge_allowed) {
target_speed = calc_speed_nudge(target_speed, g.speed_cruise, g.throttle_cruise * 0.01f);
}
// get acceleration limited target speed
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target_speed = attitude_control.get_desired_speed_accel_limited(target_speed, rover.G_Dt);
// apply object avoidance to desired speed using half vehicle's maximum deceleration
if (avoidance_enabled) {
g2.avoid.adjust_speed(0.0f, 0.5f * attitude_control.get_decel_max(), ahrs.yaw, target_speed, rover.G_Dt);
}
// call throttle controller and convert output to -100 to +100 range
float throttle_out;
// call speed or stop controller
if (is_zero(target_speed)) {
bool stopped;
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throttle_out = 100.0f * attitude_control.get_throttle_out_stop(g2.motors.limit.throttle_lower, g2.motors.limit.throttle_upper, g.speed_cruise, g.throttle_cruise * 0.01f, rover.G_Dt, stopped);
} else {
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throttle_out = 100.0f * attitude_control.get_throttle_out_speed(target_speed, g2.motors.limit.throttle_lower, g2.motors.limit.throttle_upper, g.speed_cruise, g.throttle_cruise * 0.01f, rover.G_Dt);
}
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// if vehicle is balance bot, calculate actual throttle required for balancing
if (rover.is_balancebot()) {
rover.balancebot_pitch_control(throttle_out, rover.arming.is_armed());
}
// send to motor
g2.motors.set_throttle(throttle_out);
}
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// performs a controlled stop with steering centered
bool Mode::stop_vehicle()
{
// call throttle controller and convert output to -100 to +100 range
bool stopped = false;
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float throttle_out = 100.0f * attitude_control.get_throttle_out_stop(g2.motors.limit.throttle_lower, g2.motors.limit.throttle_upper, g.speed_cruise, g.throttle_cruise * 0.01f, rover.G_Dt, stopped);
// send to motor
g2.motors.set_throttle(throttle_out);
// do not attempt to steer
g2.motors.set_steering(0.0f);
// return true once stopped
return stopped;
}
// estimate maximum vehicle speed (in m/s)
// cruise_speed is in m/s, cruise_throttle should be in the range -1 to +1
float Mode::calc_speed_max(float cruise_speed, float cruise_throttle) const
{
float speed_max;
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// sanity checks
if (cruise_throttle > 1.0f || cruise_throttle < 0.05f) {
speed_max = cruise_speed;
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} else {
// project vehicle's maximum speed
speed_max = (1.0f / cruise_throttle) * cruise_speed;
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}
// constrain to 30m/s (108km/h) and return
return constrain_float(speed_max, 0.0f, 30.0f);
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}
// calculate pilot input to nudge speed up or down
// target_speed should be in meters/sec
// cruise_speed is vehicle's cruising speed, cruise_throttle is the throttle (from -1 to +1) that achieves the cruising speed
// return value is a new speed (in m/s) which up to the projected maximum speed based on the cruise speed and cruise throttle
float Mode::calc_speed_nudge(float target_speed, float cruise_speed, float cruise_throttle)
{
// return immediately if pilot is not attempting to nudge speed
// pilot can nudge up speed if throttle (in range -100 to +100) is above 50% of center in direction of travel
const int16_t pilot_throttle = constrain_int16(rover.channel_throttle->get_control_in(), -100, 100);
if (((pilot_throttle <= 50) && (target_speed >= 0.0f)) ||
((pilot_throttle >= -50) && (target_speed <= 0.0f))) {
return target_speed;
}
// sanity checks
if (cruise_throttle > 1.0f || cruise_throttle < 0.05f) {
return target_speed;
}
// project vehicle's maximum speed
const float vehicle_speed_max = calc_speed_max(cruise_speed, cruise_throttle);
// return unadjusted target if already over vehicle's projected maximum speed
if (fabsf(target_speed) >= vehicle_speed_max) {
return target_speed;
}
const float speed_increase_max = vehicle_speed_max - fabsf(target_speed);
float speed_nudge = ((static_cast<float>(abs(pilot_throttle)) - 50.0f) * 0.02f) * speed_increase_max;
if (pilot_throttle < 0) {
speed_nudge = -speed_nudge;
}
return target_speed + speed_nudge;
}
// calculated a reduced speed(in m/s) based on yaw error and lateral acceleration and/or distance to a waypoint
// should be called after calc_lateral_acceleration and before calc_throttle
// relies on these internal members being updated: _yaw_error_cd, _distance_to_destination
float Mode::calc_reduced_speed_for_turn_or_distance(float desired_speed)
{
// reduce speed to zero during pivot turns
if (rover.use_pivot_steering(_yaw_error_cd)) {
return 0.0f;
}
// reduce speed to limit overshoot from line between origin and destination
// calculate number of degrees vehicle must turn to face waypoint
const float heading_cd = is_negative(desired_speed) ? wrap_180_cd(ahrs.yaw_sensor + 18000) : ahrs.yaw_sensor;
const float wp_yaw_diff = wrap_180_cd(rover.nav_controller->target_bearing_cd() - heading_cd);
const float turn_angle_rad = fabsf(radians(wp_yaw_diff * 0.01f));
// calculate distance from vehicle to line + wp_overshoot
const float line_yaw_diff = wrap_180_cd(get_bearing_cd(_origin, _destination) - heading_cd);
const float crosstrack_error = rover.nav_controller->crosstrack_error();
const float dist_from_line = fabsf(crosstrack_error);
const bool heading_away = is_positive(line_yaw_diff) == is_positive(crosstrack_error);
const float wp_overshoot_adj = heading_away ? -dist_from_line : dist_from_line;
// calculate radius of circle that touches vehicle's current position and heading and target position and heading
float radius_m = 999.0f;
float radius_calc_denom = fabsf(1.0f - cosf(turn_angle_rad));
if (!is_zero(radius_calc_denom)) {
radius_m = MAX(0.0f, rover.g.waypoint_overshoot + wp_overshoot_adj) / radius_calc_denom;
}
// calculate and limit speed to allow vehicle to stay on circle
float overshoot_speed_max = safe_sqrt(g.turn_max_g * GRAVITY_MSS * MAX(g2.turn_radius, radius_m));
float speed_max = constrain_float(desired_speed, -overshoot_speed_max, overshoot_speed_max);
// limit speed based on distance to waypoint and max acceleration/deceleration
if (is_positive(_distance_to_destination) && is_positive(attitude_control.get_decel_max())) {
const float dist_speed_max = safe_sqrt(2.0f * _distance_to_destination * attitude_control.get_decel_max() + sq(_desired_speed_final));
speed_max = constrain_float(speed_max, -dist_speed_max, dist_speed_max);
}
// return minimum speed
return speed_max;
}
// calculate the lateral acceleration target to cause the vehicle to drive along the path from origin to destination
// this function updates the _yaw_error_cd value
void Mode::calc_steering_to_waypoint(const struct Location &origin, const struct Location &destination, bool reversed)
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{
// record system time of call
last_steer_to_wp_ms = AP_HAL::millis();
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// Calculate the required turn of the wheels
// negative error = left turn
// positive error = right turn
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rover.nav_controller->set_reverse(reversed);
rover.nav_controller->update_waypoint(origin, destination, g.waypoint_radius);
float desired_lat_accel = rover.nav_controller->lateral_acceleration();
float desired_heading = rover.nav_controller->target_bearing_cd();
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if (reversed) {
desired_heading = wrap_360_cd(desired_heading + 18000);
desired_lat_accel *= -1.0f;
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}
_yaw_error_cd = wrap_180_cd(desired_heading - ahrs.yaw_sensor);
if (rover.use_pivot_steering(_yaw_error_cd)) {
// for pivot turns use heading controller
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calc_steering_to_heading(desired_heading, g2.pivot_turn_rate);
} else {
// call lateral acceleration to steering controller
calc_steering_from_lateral_acceleration(desired_lat_accel, reversed);
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}
}
/*
calculate steering output given lateral_acceleration
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*/
void Mode::calc_steering_from_lateral_acceleration(float lat_accel, bool reversed)
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{
// add obstacle avoidance response to lateral acceleration target
// ToDo: replace this type of object avoidance with path planning
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if (!reversed) {
lat_accel += (rover.obstacle.turn_angle / 45.0f) * g.turn_max_g;
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}
// constrain to max G force
lat_accel = constrain_float(lat_accel, -g.turn_max_g * GRAVITY_MSS, g.turn_max_g * GRAVITY_MSS);
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// send final steering command to motor library
const float steering_out = attitude_control.get_steering_out_lat_accel(lat_accel,
g2.motors.limit.steer_left,
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g2.motors.limit.steer_right,
rover.G_Dt);
g2.motors.set_steering(steering_out * 4500.0f);
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}
// calculate steering output to drive towards desired heading
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void Mode::calc_steering_to_heading(float desired_heading_cd, float rate_max, bool reversed)
{
// calculate yaw error so it can be used for reporting and slowing the vehicle
_yaw_error_cd = wrap_180_cd(desired_heading_cd - ahrs.yaw_sensor);
// call heading controller
const float steering_out = attitude_control.get_steering_out_heading(radians(desired_heading_cd*0.01f),
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rate_max,
g2.motors.limit.steer_left,
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g2.motors.limit.steer_right,
rover.G_Dt);
g2.motors.set_steering(steering_out * 4500.0f);
}
// calculate vehicle stopping point using current location, velocity and maximum acceleration
void Mode::calc_stopping_location(Location& stopping_loc)
{
// default stopping location
stopping_loc = rover.current_loc;
// get current velocity vector and speed
const Vector2f velocity = ahrs.groundspeed_vector();
const float speed = velocity.length();
// avoid divide by zero
if (!is_positive(speed)) {
stopping_loc = rover.current_loc;
return;
}
// get stopping distance in meters
const float stopping_dist = attitude_control.get_stopping_distance(speed);
// calculate stopping position from current location in meters
const Vector2f stopping_offset = velocity.normalized() * stopping_dist;
location_offset(stopping_loc, stopping_offset.x, stopping_offset.y);
}