PX4-Autopilot/src/modules/rover_differential/DifferentialSpeedControl/DifferentialSpeedControl.cpp

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#include "DifferentialSpeedControl.hpp"

using namespace time_literals;

DifferentialSpeedControl::DifferentialSpeedControl(ModuleParams *parent) : ModuleParams(parent)
{
	_rover_throttle_setpoint_pub.advertise();
	_rover_speed_status_pub.advertise();
	updateParams();
}

void DifferentialSpeedControl::updateParams()
{
	ModuleParams::updateParams();

	// Set up PID controller
	_pid_speed.setGains(_param_ro_speed_p.get(), _param_ro_speed_i.get(), 0.f);
	_pid_speed.setIntegralLimit(1.f);
	_pid_speed.setOutputLimit(1.f);

	// Set up slew rate
	if (_param_ro_accel_limit.get() > FLT_EPSILON) {
		_adjusted_speed_setpoint.setSlewRate(_param_ro_accel_limit.get());
	}
}

void DifferentialSpeedControl::updateSpeedControl()
{
	updateSubscriptions();

	const hrt_abstime timestamp_prev = _timestamp;
	_timestamp = hrt_absolute_time();
	const float dt = math::constrain(_timestamp - timestamp_prev, 1_ms, 10_ms) * 1e-6f;

	// Throttle Setpoint
	if (PX4_ISFINITE(_speed_setpoint)) {
		const float speed_setpoint = calcSpeedSetpoint();
		rover_throttle_setpoint_s rover_throttle_setpoint{};
		rover_throttle_setpoint.timestamp = _timestamp;
		rover_throttle_setpoint.throttle_body_x = RoverControl::speedControl(_adjusted_speed_setpoint, _pid_speed,
				speed_setpoint, _vehicle_speed, _param_ro_accel_limit.get(), _param_ro_decel_limit.get(),
				_param_ro_max_thr_speed.get(), dt);
		rover_throttle_setpoint.throttle_body_y = 0.f;
		_rover_throttle_setpoint_pub.publish(rover_throttle_setpoint);
	}

	// Publish speed controller status (logging only)
	rover_speed_status_s rover_speed_status;
	rover_speed_status.timestamp = _timestamp;
	rover_speed_status.measured_speed_body_x = _vehicle_speed;
	rover_speed_status.adjusted_speed_body_x_setpoint = _adjusted_speed_setpoint.getState();
	rover_speed_status.pid_throttle_body_x_integral = _pid_speed.getIntegral();
	rover_speed_status.measured_speed_body_y = NAN;
	rover_speed_status.adjusted_speed_body_y_setpoint = NAN;
	rover_speed_status.pid_throttle_body_y_integral = NAN;
	_rover_speed_status_pub.publish(rover_speed_status);
}

void DifferentialSpeedControl::updateSubscriptions()
{
	if (_vehicle_attitude_sub.updated()) {
		vehicle_attitude_s vehicle_attitude{};
		_vehicle_attitude_sub.copy(&vehicle_attitude);
		_vehicle_attitude_quaternion = matrix::Quatf(vehicle_attitude.q);
	}

	if (_vehicle_local_position_sub.updated()) {
		vehicle_local_position_s vehicle_local_position{};
		_vehicle_local_position_sub.copy(&vehicle_local_position);
		Vector3f velocity_ned(vehicle_local_position.vx, vehicle_local_position.vy, vehicle_local_position.vz);
		Vector3f velocity_xyz = _vehicle_attitude_quaternion.rotateVectorInverse(velocity_ned);
		Vector2f velocity_2d = Vector2f(velocity_xyz(0), velocity_xyz(1));
		_vehicle_speed = velocity_2d.norm() > _param_ro_speed_th.get() ? sign(velocity_2d(0)) * velocity_2d.norm() : 0.f;
	}

	if (_rover_speed_setpoint_sub.updated()) {
		rover_speed_setpoint_s rover_speed_setpoint;
		_rover_speed_setpoint_sub.copy(&rover_speed_setpoint);
		_speed_setpoint = rover_speed_setpoint.speed_body_x;
	}

}

float DifferentialSpeedControl::calcSpeedSetpoint()
{
	float speed_setpoint = math::constrain(_speed_setpoint, -_param_ro_speed_limit.get(), _param_ro_speed_limit.get());

	const float speed_setpoint_normalized = math::interpolate<float>(speed_setpoint,
						-_param_ro_max_thr_speed.get(), _param_ro_max_thr_speed.get(), -1.f, 1.f);

	if (_rover_steering_setpoint_sub.updated()) {
		rover_steering_setpoint_s rover_steering_setpoint{};
		_rover_steering_setpoint_sub.copy(&rover_steering_setpoint);
		_normalized_speed_diff = rover_steering_setpoint.normalized_steering_setpoint;
	}

	if (fabsf(speed_setpoint_normalized) > 1.f - fabsf(
		    _normalized_speed_diff)) { // Adjust speed setpoint if it is infeasible due to the desired speed difference of the left/right wheels
		speed_setpoint = math::interpolate<float>(sign(speed_setpoint_normalized) * (1.f - fabsf(_normalized_speed_diff)), -1.f,
				 1.f, -_param_ro_max_thr_speed.get(), _param_ro_max_thr_speed.get());
	}

	return speed_setpoint;
}

bool DifferentialSpeedControl::runSanityChecks()
{
	bool ret = true;

	if (_param_ro_speed_limit.get() < FLT_EPSILON) {
		ret = false;
		events::send<float>(events::ID("differential_speed_control_conf_invalid_speed_lim"), events::Log::Error,
				    "Invalid configuration of necessary parameter RO_SPEED_LIM", _param_ro_speed_limit.get());
	}

	if (_param_ro_max_thr_speed.get() < FLT_EPSILON && _param_ro_speed_p.get() < FLT_EPSILON) {
		ret = false;
		events::send<float, float>(events::ID("differential_speed_control_conf_invalid_speed_control"), events::Log::Error,
					   "Invalid configuration for speed control: Neither feed forward (RO_MAX_THR_SPEED) nor feedback (RO_SPEED_P) is setup",
					   _param_ro_max_thr_speed.get(), _param_ro_speed_p.get());
	}

	return ret;
}