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scoutos / scout / motors / src / motors.cpp @ 3a73516c

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/**
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 * Copyright (c) 2011 Colony Project
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 * 
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 * Permission is hereby granted, free of charge, to any person
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 * obtaining a copy of this software and associated documentation
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 * files (the "Software"), to deal in the Software without
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 * restriction, including without limitation the rights to use,
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 * copy, modify, merge, publish, distribute, sublicense, and/or sell
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 * copies of the Software, and to permit persons to whom the
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 * Software is furnished to do so, subject to the following
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 * conditions:
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 * 
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 * The above copyright notice and this permission notice shall be
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 * included in all copies or substantial portions of the Software.
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 * 
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 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
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 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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 * OTHER DEALINGS IN THE SOFTWARE.
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 */
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/**
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 * @file motors.cpp
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 * @brief Contains code to control the motors.
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 *
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 * @defgroup motors Motors
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 * @brief Functions for using the motors
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 *
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 * @author Colony Project, CMU Robotics Club
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 * @author Ben Wasserman
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 * @author Tom Mullins
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 *
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 * @{
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 */
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#include <ros/ros.h>
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#include <cstdlib>
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#include "motors.h"
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using namespace std;
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/**
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 * @brief Motor constructor
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 *
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 * Opens device file and reads initial PWM value
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 *
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 * @param filename The name of the PWM device file
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 */
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Motor::Motor(int pwm_gpt, int in1_gpio, int in2_gpio)
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{
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    char buf[60];
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    // open device files
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    sprintf(buf, "/dev/pwm%d", pwm_gpt);
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    fpwm.open(buf, ios::out);
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    sprintf(buf, "/sys/class/gpio/gpio%d/value", in1_gpio);
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    fin1.open(buf, ios::out);
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    sprintf(buf, "/sys/class/gpio/gpio%d/value", in2_gpio);
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    fin2.open(buf, ios::out);
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    /* I set speed to 0 here rather than reading in what the current speed is
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     * because the pwm driver does not support seeking in the device files.
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     * Doing both reading and writing causes fpwm to attempt seeking, which
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     * fails, causing fpwm to refuse to do any more io. So, we can only write.
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     */
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    speed = 0;
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    // ensure we are in a consistent state by writing to hardware
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    set_speed(speed);
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}
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/**
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 * @brief Motor destructor
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 *
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 * Sets the motor's speed to zero in preparation for the node exiting
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 */
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Motor::~Motor()
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{
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    set_speed(0);
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}
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/**
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 * @brief Returns current motor speed
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 *
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 * Note that this doesn't read from the hardware
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 */
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int Motor::get_speed()
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{
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    return speed;
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}
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/**
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 * @brief Sets motor speed
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 *
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 * This will set the member this->speed and write the new speed to the hardware
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 *
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 * @param new_speed The speed to set, between +/- MAXSPEED inclusive
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 */
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void Motor::set_speed(int new_speed)
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{
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    int pwm, in1, in2;
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    speed = new_speed;
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    // convert to hardware units
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    if (speed == 0)
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    {
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        /// @todo should this be off (00) or short brake (11)?
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        pwm = 0;
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        in1 = 0;
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        in2 = 0;
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    }
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    else if (speed > 0)
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    {
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        // CW
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        pwm = speed;
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        in1 = 1;
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        in2 = 0;
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    }
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    else
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    {
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        // CCW
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        pwm = -speed;
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        in1 = 0;
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        in2 = 1;
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    }
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    // write to hardware
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    fpwm << pwm << flush;
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    fin1 << in1 << flush;
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    fin2 << in2 << flush;
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}
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/// @todo change these to the correct motor locations / directions
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// Motor state variables
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static Motor motor_fl( 8, 70, 71);
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static Motor motor_fr( 9, 72, 73);
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static Motor motor_bl(11, 74, 75);
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static Motor motor_br(10, 76, 77);
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/**
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 * @brief Sets motor speed
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 *
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 * Sets the motor speeds based on subscription to the set_motors topic.
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 *
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 * @param msg The message from the set_motors topic, containing speeds and
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 *  motor configuration settings.
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 */
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void motors_set(const ::messages::set_motors::ConstPtr& msg)
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{
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    if(msg->fl_set)
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    {
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        motor_fl.set_speed(msg->fl_speed);
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    }
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    if(msg->fr_set)
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    {
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        motor_fr.set_speed(msg->fr_speed);
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    }
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    if(msg->bl_set)
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    {
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        motor_bl.set_speed(msg->bl_speed);
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    }
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    if(msg->br_set)
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    {
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        motor_br.set_speed(msg->br_speed);
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    }
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    ROS_DEBUG("Motor speeds set");
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}
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/**
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 * @brief Outputs current motor speeds
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 *
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 * Serves the service query_motors by responding to service requests with the
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 * speeds of the motors.
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 * @param req The request. The only field is the units requested.
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 * @param res The response. The fields will be filled with values.
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 */
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bool motors_query(::messages::query_motors::Request &req,
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                  ::messages::query_motors::Response &res)
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{
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    res.fl_speed = motor_fl.get_speed();
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    res.fr_speed = motor_fr.get_speed();
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    res.bl_speed = motor_bl.get_speed();
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    res.br_speed = motor_br.get_speed();
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    ROS_DEBUG("Motor speeds queried");
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    return true;
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}
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/**
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 * @brief Motors driver. This is a ROS node that controls motor speeds.
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 *
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 * This is the main function for the motors node. It is run when the node
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 * starts and initializes the motors. It then subscribes to the
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 * set_motors, and set_motor_speeds topics, and advertises the
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 * query_motors service.
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 * 
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 * @param argc The number of command line arguments (should be 1)
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 * @param argv The array of command line arguments
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 */
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int main(int argc, char **argv)
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{
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    /* Initialize in ROS the motors driver node */
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    ros::init(argc, argv, "motors_driver");
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    /* Advertise that this serves the query_motors service */
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    ros::NodeHandle node;
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    ros::ServiceServer service = node.advertiseService("query_motors",
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                                                       motors_query);
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    /* Subscribe to the set_motors topic */
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    ros::Subscriber sub0 = node.subscribe("set_motors", QUEUE_SIZE, motors_set);
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    ROS_INFO("Motors node ready.");
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    ros::spin();
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    return 0;
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}
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/** @} */