137 lines
4.8 KiB
C++
137 lines
4.8 KiB
C++
/*
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Copyright (c) 2016, Juan Jimeno
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Source: http://research.ijcaonline.org/volume113/number3/pxc3901586.pdf
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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Redistributions of source code must retain the above copyright notice,
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this list of conditions and the following disclaimer.
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Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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Neither the name of nor the names of its contributors may be used to
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endorse or promote products derived from this software without specific
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prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORTPPIPI (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "Arduino.h"
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#include "Kinematics.h"
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Kinematics::Kinematics(int motor_max_rpm, float wheel_diameter, float fr_wheels_dist, float lr_wheels_dist, int pwm_bits):
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circumference_(PI * wheel_diameter),
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max_rpm_(motor_max_rpm),
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fr_wheels_dist_(fr_wheels_dist),
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lr_wheels_dist_(lr_wheels_dist),
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pwm_res_ (pow(2, pwm_bits) - 1)
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{
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}
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Kinematics::output Kinematics::getRPM(float linear_x, float linear_y, float angular_z)
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{
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//convert m/s to m/min
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linear_vel_x_mins_ = linear_x * 60;
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linear_vel_y_mins_ = linear_y * 60;
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//convert rad/s to rad/min
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angular_vel_z_mins_ = angular_z * 60;
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//Vt = ω * radius
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tangential_vel_ = angular_vel_z_mins_ * lr_wheels_dist_;
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x_rpm_ = linear_vel_x_mins_ / circumference_;
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y_rpm_ = linear_vel_y_mins_ / circumference_;
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tan_rpm_ = tangential_vel_ / circumference_;
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Kinematics::output rpm;
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//calculate for the target motor RPM and direction
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//front-left motor
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rpm.motor1 = x_rpm_ - y_rpm_ - tan_rpm_;
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//rear-left motor
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rpm.motor3 = x_rpm_ + y_rpm_ - tan_rpm_;
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//front-right motor
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rpm.motor2 = x_rpm_ + y_rpm_ + tan_rpm_;
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//rear-right motor
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rpm.motor4 = x_rpm_ - y_rpm_ + tan_rpm_;
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return rpm;
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}
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Kinematics::output Kinematics::getPWM(float linear_x, float linear_y, float angular_z)
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{
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Kinematics::output rpm;
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Kinematics::output pwm;
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rpm = getRPM(linear_x, linear_y, angular_z);
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//convert from RPM to PWM
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//front-left motor
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pwm.motor1 = rpmToPWM(rpm.motor1);
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//rear-left motor
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pwm.motor2 = rpmToPWM(rpm.motor2);
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//front-right motor
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pwm.motor3 = rpmToPWM(rpm.motor3);
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//rear-right motor
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pwm.motor4 = rpmToPWM(rpm.motor4);
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return pwm;
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}
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Kinematics::velocities Kinematics::getVelocities(int motor1, int motor2)
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{
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Kinematics::velocities vel;
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float average_rpm_x = (float)(motor1 + motor2) / 2; // RPM
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//convert revolutions per minute to revolutions per second
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float average_rps_x = average_rpm_x / 60; // RPS
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vel.linear_x = (average_rps_x * circumference_); // m/s
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float average_rpm_a = (float)(motor2 - motor1) / 2;
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//convert revolutions per minute to revolutions per second
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float average_rps_a = average_rpm_a / 60;
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vel.angular_z = (average_rps_a * circumference_) / (lr_wheels_dist_ / 2);
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return vel;
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}
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Kinematics::velocities Kinematics::getVelocities(int motor1, int motor2, int motor3, int motor4)
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{
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Kinematics::velocities vel;
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float average_rpm_x = (float)(motor1 + motor2 + motor3 + motor4) / 4; // RPM
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//convert revolutions per minute to revolutions per second
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float average_rps_x = average_rpm_x / 60; // RPS
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vel.linear_x = (average_rps_x * circumference_); // m/s
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float average_rpm_y = (float)(-motor1 + motor2 + motor3 - motor4) / 4; // RPM
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//convert revolutions per minute in y axis to revolutions per second
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float average_rps_y = average_rpm_y / 60; // RPS
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vel.linear_y = (average_rps_y * circumference_); // m/s
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float average_rpm_a = (float)(-motor1 + motor2 - motor3 + motor4) / 4;
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//convert revolutions per minute to revolutions per second
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float average_rps_a = average_rpm_a / 60;
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vel.angular_z = (average_rps_a * circumference_) / ((fr_wheels_dist_ / 2) + (lr_wheels_dist_ / 2));
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return vel;
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}
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int Kinematics::rpmToPWM(int rpm)
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{
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//remap scale of target RPM vs MAX_RPM to PWM
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return (((float) rpm / (float) max_rpm_) * pwm_res_);
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}
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