Colony » Colony Scout

/**

 * Copyright (c) 2011 Colony Project

 * 

 * Permission is hereby granted, free of charge, to any person

 * obtaining a copy of this software and associated documentation

 * files (the "Software"), to deal in the Software without

 * restriction, including without limitation the rights to use,

 * copy, modify, merge, publish, distribute, sublicense, and/or sell

 * copies of the Software, and to permit persons to whom the

 * Software is furnished to do so, subject to the following

 * conditions:

 * 

 * The above copyright notice and this permission notice shall be

 * included in all copies or substantial portions of the Software.

 * 

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,

 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES

 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND

 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT

 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,

 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR

 * OTHER DEALINGS IN THE SOFTWARE.

 */

/**

 * @file motors.cpp

 * @brief Contains code to control the motors.

 *

 * Implementation of functions for motor use.

 *

 * @author Colony Project, CMU Robotics Club

 * @author Ben Wasserman

 * @author Tom Mullins

 */

#include <ros/ros.h>

#include <cstdlib>

#include "motors.h"

using namespace std;

/**

 * @defgroup motors Motors

 * @brief Functions for using the motors

 *

 * @{

 */

/**

 * @brief Motor constructor

 *

 * Opens device file and reads initial PWM value

 *

 * @param filename The name of the PWM device file

 */

Motor::Motor(int pwm_gpt, int in1_gpio, int in2_gpio)

{

    char buf[60];

    // open device files

    sprintf(buf, "/dev/pwm%d", pwm_gpt);

    fpwm.open(buf, ios::out);

    sprintf(buf, "/sys/class/gpio/gpio%d/value", in1_gpio);

    fin1.open(buf, ios::out);

    sprintf(buf, "/sys/class/gpio/gpio%d/value", in2_gpio);

    fin2.open(buf, ios::out);

    /* I set speed to 0 here rather than reading in what the current speed is

     * because the pwm driver does not support seeking in the device files.

     * Doing both reading and writing causes fpwm to attempt seeking, which

     * fails, causing fpwm to refuse to do any more io. So, we can only write.

     */

    speed = 0;

    // ensure we are in a consistent state by writing to hardware

    set_speed(speed);

}

/**

 * @brief Motor destructor

 *

 * Sets the motor's speed to zero in preparation for the node exiting

 */

Motor::~Motor()

{

    set_speed(0);

}

/**

 * @brief Returns current motor speed

 *

 * Note that this doesn't read from the hardware

 */

int Motor::get_speed()

{

    return speed;

}

/**

 * @brief Sets motor speed

 *

 * This will set the member this->speed and write the new speed to the hardware

 *

 * @param new_speed The speed to set, between +/- MAXSPEED inclusive

 */

void Motor::set_speed(int new_speed)

{

    int pwm, in1, in2;

    speed = new_speed;

    // convert to hardware units

    if (speed == 0)

    {

        /// @todo should this be off (00) or short brake (11)?

        pwm = 0;

        in1 = 0;

        in2 = 0;

    }

    else if (speed > 0)

    {

        // CW

        pwm = speed;

        in1 = 1;

        in2 = 0;

    }

    else

    {

        // CCW

        pwm = -speed;

        in1 = 0;

        in2 = 1;

    }

    // write to hardware

    fpwm << pwm << flush;

    fin1 << in1 << flush;

    fin2 << in2 << flush;

}

/// @todo change these to the correct motor locations / directions

// Motor state variables

static Motor motor_fl( 8, 70, 71);

static Motor motor_fr( 9, 72, 73);

static Motor motor_bl(11, 74, 75);

static Motor motor_br(10, 76, 77);

/**

 * @brief Sets motor speed

 *

 * Sets the motor speeds based on subscription to the set_motors topic.

 *

 * @param msg The message from the set_motors topic, containing speeds and

 *  motor configuration settings.

 */

void motors_set(const ::messages::set_motors::ConstPtr& msg)

{

    if(msg->fl_set)

    {

        motor_fl.set_speed(msg->fl_speed);

    }

    if(msg->fr_set)

    {

        motor_fr.set_speed(msg->fr_speed);

    }

    if(msg->bl_set)

    {

        motor_bl.set_speed(msg->bl_speed);

    }

    if(msg->br_set)

    {

        motor_br.set_speed(msg->br_speed);

    }

    ROS_DEBUG("Motor speeds set");

}

/**

 * @brief Outputs current motor speeds

 *

 * Serves the service query_motors by responding to service requests with the

 * speeds of the motors.

 * @param req The request. The only field is the units requested.

 * @param res The response. The fields will be filled with values.

 */

bool motors_query(::messages::query_motors::Request &req,

                  ::messages::query_motors::Response &res)

{

    res.fl_speed = motor_fl.get_speed();

    res.fr_speed = motor_fr.get_speed();

    res.bl_speed = motor_bl.get_speed();

    res.br_speed = motor_br.get_speed();

    ROS_DEBUG("Motor speeds queried");

    return true;

}

/**

 * @brief Motors driver. This is a ROS node that controls motor speeds.

 *

 * This is the main function for the motors node. It is run when the node

 * starts and initializes the motors. It then subscribes to the

 * set_motors, and set_motor_speeds topics, and advertises the

 * query_motors service.

 * 

 * @param argc The number of command line arguments (should be 1)

 * @param argv The array of command line arguments

 */

int main(int argc, char **argv)

{

    /* Initialize in ROS the motors driver node */

    ros::init(argc, argv, "motors_driver");

    /* Advertise that this serves the query_motors service */

    ros::NodeHandle node;

    ros::ServiceServer service = node.advertiseService("query_motors",

                                                       motors_query);

    /* Subscribe to the set_motors topic */

    ros::Subscriber sub0 = node.subscribe("set_motors", QUEUE_SIZE, motors_set);

    ROS_INFO("Motors node ready.");

    ros::spin();

    return 0;

}

/** @} */