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/****************************************************************************
*
* Copyright (c) 2014 PX4 Development Team. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name PX4 nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/**
* @file mc_mixer.cpp
* Dummy multicopter mixer for euroc simulator (gazebo)
*
* @author Roman Bapst <romanbapst@yahoo.de>
*/
#include <ros/ros.h>
#include <px4.h>
#include <lib/mathlib/mathlib.h>
#include <mav_msgs/MotorSpeed.h>
class MultirotorMixer {
public:
MultirotorMixer();
struct Rotor {
float roll_scale;
float pitch_scale;
float yaw_scale;
};
void actuatorControlsCallback(const PX4_TOPIC_T(actuator_controls_0) &msg);
private:
ros::NodeHandle _n;
ros::Subscriber _sub;
ros::Publisher _pub;
const Rotor *_rotors;
unsigned _rotor_count;
struct {
float control[6];
}inputs;
struct {
float control[6];
}outputs;
void mix();
};
const MultirotorMixer::Rotor _config_x[] = {
{ -0.707107, 0.707107, 1.00 },
{ 0.707107, -0.707107, 1.00 },
{ 0.707107, 0.707107, -1.00 },
{ -0.707107, -0.707107, -1.00 },
};
const MultirotorMixer::Rotor _config_quad_plus[] = {
{ -1.000000, 0.000000, 1.00 },
{ 1.000000, 0.000000, 1.00 },
{ 0.000000, 1.000000, -1.00 },
{ -0.000000, -1.000000, -1.00 },
};
const MultirotorMixer::Rotor *_config_index[3] = {
&_config_x[0],
&_config_quad_plus[0],
};
MultirotorMixer::MultirotorMixer():
_n(),
_rotor_count(4),
_rotors(_config_index[1]) //XXX +config hardcoded
{
_sub = _n.subscribe("actuator_controls_0", 1000, &MultirotorMixer::actuatorControlsCallback,this);
_pub = _n.advertise<mav_msgs::MotorSpeed>("/mixed_motor_commands",10);
if (!_n.hasParam("motor_scaling_radps")) {
_n.setParam("motor_scaling_radps", 1500.0);
}
}
void MultirotorMixer::mix() {
float roll = math::constrain(inputs.control[0], -1.0f, 1.0f);
float pitch = math::constrain(inputs.control[1], -1.0f, 1.0f);
float yaw = math::constrain(inputs.control[2], -1.0f, 1.0f);
float thrust = math::constrain(inputs.control[3], 0.0f, 1.0f);
float min_out = 0.0f;
float max_out = 0.0f;
/* perform initial mix pass yielding unbounded outputs, ignore yaw */
for (unsigned i = 0; i < _rotor_count; i++) {
float out = roll * _rotors[i].roll_scale
+ pitch * _rotors[i].pitch_scale + thrust;
/* limit yaw if it causes outputs clipping */
if (out >= 0.0f && out < -yaw * _rotors[i].yaw_scale) {
yaw = -out / _rotors[i].yaw_scale;
}
/* calculate min and max output values */
if (out < min_out) {
min_out = out;
}
if (out > max_out) {
max_out = out;
}
outputs.control[i] = out;
}
/* scale down roll/pitch controls if some outputs are negative, don't add yaw, keep total thrust */
if (min_out < 0.0f) {
float scale_in = thrust / (thrust - min_out);
/* mix again with adjusted controls */
for (unsigned i = 0; i < _rotor_count; i++) {
outputs.control[i] = scale_in
* (roll * _rotors[i].roll_scale
+ pitch * _rotors[i].pitch_scale) + thrust;
}
} else {
/* roll/pitch mixed without limiting, add yaw control */
for (unsigned i = 0; i < _rotor_count; i++) {
outputs.control[i] += yaw * _rotors[i].yaw_scale;
}
}
/* scale down all outputs if some outputs are too large, reduce total thrust */
float scale_out;
if (max_out > 1.0f) {
scale_out = 1.0f / max_out;
} else {
scale_out = 1.0f;
}
/* scale outputs to range _idle_speed..1, and do final limiting */
for (unsigned i = 0; i < _rotor_count; i++) {
outputs.control[i] = math::constrain(outputs.control[i], 0.0f, 1.0f);
}
}
void MultirotorMixer::actuatorControlsCallback(const PX4_TOPIC_T(actuator_controls_0) &msg)
{
// read message
for(int i = 0;i < msg.NUM_ACTUATOR_CONTROLS;i++) {
inputs.control[i] = msg.control[i];
}
// mix
mix();
// publish message
mav_msgs::MotorSpeed rotor_vel_msg;
double scaling;
_n.getParamCached("motor_scaling_radps", scaling);
for (int i = 0; i < _rotor_count; i++) {
rotor_vel_msg.motor_speed.push_back(outputs.control[i] * scaling);
}
_pub.publish(rotor_vel_msg);
}
int main(int argc, char **argv)
{
ros::init(argc, argv, "mc_mixer");
MultirotorMixer mixer;
ros::spin();
return 0;
}
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