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 LinesensorControl.cpp

 * @brief Contains line following function implementation

 *

 * @defgroup linesensorcontrol LinesensorControl

 * @brief Functions which a behavior can use to control the line sensor.

 * @ingroup behavior

 * 

 * @author Colony Project, CMU Robotics Club

 * @author Alex Zirbel

 *

 * @{

 */

#include "LinesensorControl.h"

using namespace std;

static double last_ret;

/**

 * @brief Initialize the line following module of libscout.

 */

LinesensorControl::LinesensorControl(const ros::NodeHandle& libscout_node,

                                 string scoutname)

    : node(libscout_node)

{

    query_client =

        node.serviceClient< ::messages::query_linesensor>(scoutname+"/query_linesensor");

}

/**

 * @brief Returns the current readings of the line follwing sensor.

 */

vector<uint32_t> LinesensorControl::query()

{

    // Set scan range

    ::messages::query_linesensor srv;

    if (!query_client.call(srv))

    {

        ROS_ERROR("LinesensorControl query failed.");

    }

    if (srv.response.readings.size() != 8)

    {

        ROS_WARN("Linesensor reading vector has %d readings, 8 expected.",

                 int(srv.response.readings.size()));

    }

    return srv.response.readings;

}

/** 

 *  @brief Returns the average readings of the line following sensors. 

 */

double LinesensorControl::readline()

{

    unsigned int total_read = 0;

    unsigned int weighted_total = 0;

    vector<uint32_t> readings = query();

    if (readings.size() < 8)

    {

        return last_ret;

    }

    for (int i = 0; i < 8; i++)

    {

        total_read += readings[i];

        weighted_total += i * readings[i];

    }

    if (total_read == 0)

    {

        return last_ret;

    }

    double ret_val = last_ret = ((double) weighted_total / total_read) - 3.5;

    return ret_val;

}

bool LinesensorControl::fullline(vector<uint32_t> readings)

{

    if (readings.size() < 8)

    {

        return false;

    }

    for(int i=0; i<8; i++)

    {

        if(readings[i] < 200)

          return false;

    }

    return true; 

}

/**

 * We define a destination as two gaps of white between the line and patches

 * of 95-shade color (dark grey) on either side.

 * I use 95-shade color in an attempt to not throw off the line localization.

 */

bool LinesensorControl::destination(vector<uint32_t> readings)

{

    if (readings.size() < 8)

    {

        return false;

    }

    // Try to match this pattern to what we see

    int expected_pattern[] = {95, 0, 255, 0, 95};

    int pat_idx = 0;

    for (int i = 0; i < 8; i++)

    {

        // If the difference between what we have and expect is less than 5

        if (abs(readings[i] - expected_pattern[pat_idx]) < 5)

        {

            // Check. Keep looking for the rest of the pattern.

            pat_idx++;

        }

        // The whole pattern was found

        if (pat_idx > 4)

        {

            return true;

        }

    }

    return false;

}

/** @} */