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),
mission(rover.mission),
attitude_control(rover.g2.attitude_control)
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{ }
void Mode::exit()
{
// call sub-classes exit
_exit();
lateral_acceleration = 0.0f;
}
bool Mode::enter()
{
g2.motors.slew_limit_throttle(false);
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return _enter();
}
// set desired location
void Mode::set_desired_location(const struct Location& destination, float next_leg_bearing_cd)
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{
// record targets
_origin = rover.current_loc;
_destination = destination;
_desired_speed = g.speed_cruise;
// 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)) {
// if not turning can continue at full speed
if (is_zero(next_leg_bearing_cd)) {
_desired_speed_final = _desired_speed;
} else {
// calculate maximum speed that keeps overshoot within bounds
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);
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 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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void Mode::calc_throttle(float target_speed, bool nudge_allowed)
{
// add in speed nudging
if (nudge_allowed) {
target_speed = calc_speed_nudge(target_speed, g.speed_cruise, g.throttle_cruise * 0.01f);
}
// call throttle controller and convert output to -100 to +100 range
float throttle_out = 100.0f * attitude_control.get_throttle_out_speed(target_speed, g2.motors.have_skid_steering(), g2.motors.limit.throttle_lower, g2.motors.limit.throttle_upper, g.speed_cruise, g.throttle_cruise * 0.01f);
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// 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;
float throttle_out = 100.0f * attitude_control.get_throttle_out_stop(g2.motors.have_skid_steering(), g2.motors.limit.throttle_lower, g2.motors.limit.throttle_upper, g.speed_cruise, g.throttle_cruise * 0.01f, 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)
float Mode::calc_speed_max(float cruise_speed, float cruise_throttle)
{
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 && is_positive(target_speed)) ||
(pilot_throttle >= -50 && is_negative(target_speed))) {
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 (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: lateral_acceleration, _yaw_error_cd, _distance_to_destination
float Mode::calc_reduced_speed_for_turn_or_distance(float desired_speed)
{
// this method makes use the following internal variables
const float yaw_error_cd = _yaw_error_cd;
const float target_lateral_accel_G = lateral_acceleration;
const float distance_to_waypoint = _distance_to_destination;
// calculate the yaw_error_ratio which is the error (capped at 90degrees) expressed as a ratio (from 0 ~ 1)
float yaw_error_ratio = constrain_float(fabsf(yaw_error_cd / 9000.0f), 0.0f, 1.0f);
// apply speed_turn_gain parameter (expressed as a percentage) to yaw_error_ratio
yaw_error_ratio *= (100 - g.speed_turn_gain) * 0.01f;
// calculate absolute lateral acceleration expressed as a ratio (from 0 ~ 1) of the vehicle's maximum lateral acceleration
const float lateral_accel_ratio = constrain_float(fabsf(target_lateral_accel_G / (g.turn_max_g * GRAVITY_MSS)), 0.0f, 1.0f);
// calculate a lateral acceleration based speed scaling
const float lateral_accel_speed_scaling = 1.0f - lateral_accel_ratio * yaw_error_ratio;
// calculate a pivot steering based speed scaling (default to no reduction)
float pivot_speed_scaling = 1.0f;
if (rover.use_pivot_steering(yaw_error_cd)) {
pivot_speed_scaling = 0.0f;
}
// scaled speed
float speed_scaled = desired_speed * MIN(lateral_accel_speed_scaling, pivot_speed_scaling);
// limit speed based on distance to waypoint and max acceleration/deceleration
if (is_positive(distance_to_waypoint) && is_positive(attitude_control.get_accel_max())) {
const float speed_max = safe_sqrt(2.0f * distance_to_waypoint * attitude_control.get_accel_max() + sq(_desired_speed_final));
speed_scaled = constrain_float(speed_scaled, -speed_max, speed_max);
}
// return minimum speed
return speed_scaled;
}
// calculate the lateral acceleration target to cause the vehicle to drive along the path from origin to destination
// this function update lateral_acceleration and _yaw_error_cd members
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void Mode::calc_lateral_acceleration(const struct Location &origin, const struct Location &destination, bool reversed)
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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);
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lateral_acceleration = rover.nav_controller->lateral_acceleration();
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if (reversed) {
_yaw_error_cd = wrap_180_cd(rover.nav_controller->target_bearing_cd() - ahrs.yaw_sensor + 18000);
} else {
_yaw_error_cd = wrap_180_cd(rover.nav_controller->target_bearing_cd() - ahrs.yaw_sensor);
}
if (rover.use_pivot_steering(_yaw_error_cd)) {
if (is_positive(_yaw_error_cd)) {
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lateral_acceleration = g.turn_max_g * GRAVITY_MSS;
}
if (is_negative(_yaw_error_cd)) {
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lateral_acceleration = -g.turn_max_g * GRAVITY_MSS;
}
}
}
/*
calculate steering angle given lateral_acceleration
*/
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void Mode::calc_nav_steer(bool reversed)
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{
// add obstacle avoidance response to lateral acceleration target
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if (!reversed) {
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lateral_acceleration += (rover.obstacle.turn_angle / 45.0f) * g.turn_max_g;
}
// constrain to max G force
lateral_acceleration = constrain_float(lateral_acceleration, -g.turn_max_g * GRAVITY_MSS, g.turn_max_g * GRAVITY_MSS);
// send final steering command to motor library
float steering_out = attitude_control.get_steering_out_lat_accel(lateral_acceleration, g2.motors.have_skid_steering(), g2.motors.limit.steer_left, g2.motors.limit.steer_right);
g2.motors.set_steering(steering_out * 4500.0f);
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}