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/**
* Copyright (c) 2014, Timothy Stack
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
* * 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.
* * Neither the name of Timothy Stack 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 REGENTS 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 REGENTS 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 log_accel.cc
*/
#include <algorithm>
#include "log_accel.hh"
#include "config.h"
const double log_accel::MIN_RANGE = 5.0;
const double log_accel::THRESHOLD = 0.1;
bool
log_accel::add_point(int64_t point)
{
require(this->la_velocity_size < HISTORY_SIZE);
if (this->la_last_point_set) {
// TODO Reenable this when we find the bug that causes some older
// timestamps to show up after more recent ones.
// require(this->la_last_point >= point);
// Compute the message velocity.
this->la_velocity[this->la_velocity_size]
= (this->la_last_point - point);
// Find the range of velocities so we can normalize.
this->la_min_velocity = std::min(
this->la_min_velocity, this->la_velocity[this->la_velocity_size]);
this->la_max_velocity = std::max(
this->la_max_velocity, this->la_velocity[this->la_velocity_size]);
this->la_velocity_size += 1;
}
this->la_last_point = point;
this->la_last_point_set = true;
return this->la_velocity_size < HISTORY_SIZE;
}
double
log_accel::get_avg_accel() const
{
double avg_accel = 0, total_accel = 0;
// Compute the range of values so we can normalize.
double range = (double) (this->la_max_velocity - this->la_min_velocity);
range = std::max(range, MIN_RANGE);
for (int lpc = 0; lpc < (this->la_velocity_size - 1); lpc++) {
double accel
= (this->la_velocity[lpc] - this->la_velocity[lpc + 1]) / range;
total_accel += accel;
}
if (this->la_velocity_size > 1) {
avg_accel = total_accel / (double) (this->la_velocity_size - 1);
}
return avg_accel;
}
log_accel::direction_t
log_accel::get_direction() const
{
double avg_accel = this->get_avg_accel();
direction_t retval;
if (std::fabs(avg_accel) <= THRESHOLD) {
retval = A_STEADY;
} else if (avg_accel < 0.0) {
retval = A_ACCEL;
} else {
retval = A_DECEL;
}
return retval;
}
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