root / scout / libscout / src / behaviors / Odometry.cpp @ 339f64d2
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#include "Odometry.h" |
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using namespace std; |
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/** Set up the odometry node and prepare communcations over ROS */
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Odometry::Odometry(string scoutname, Sensors* sensors):Behavior(scoutname,
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"odometry", sensors)
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{ |
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name = scoutname; |
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scout_pos = new pos;
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motor_fl_ticks = motor_fr_ticks = motor_bl_ticks = motor_br_ticks = 0;
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} |
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/** Query encoders and estimate position based on encoder reading */
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void Odometry::get_position()
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{ |
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float left_dist, right_dist, total_dist, theta;
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encoder_readings scout_enc = encoders->query(); |
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motor_fl_dist = scout_enc.fl_ticks - motor_fl_ticks; |
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motor_fr_dist = scout_enc.fr_ticks - motor_fr_ticks; |
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motor_bl_dist = scout_enc.bl_ticks - motor_bl_ticks; |
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motor_br_dist = scout_enc.br_ticks - motor_br_ticks; |
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// Get Left and Right distance
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left_dist = DIST_PER_TICK*(((float)(motor_fl_dist))/2.0 + |
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((float)(motor_bl_dist))/2.0); |
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right_dist = DIST_PER_TICK*(((float)(motor_fr_dist))/2.0 + |
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((float)(motor_br_dist))/2.0); |
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total_dist = (left_dist)/2.0 + (right_dist)/2.0; |
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theta = scout_pos->theta + atan2(right_dist - left_dist, WHEEL_BASE); |
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//Use negative theta because we measure theta from 0 on the
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//right to 180 on the left counter-clock-wise, but this is
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//negative theta in the coordinate frame.
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//Also, subtract the delta from y because positive y is down.
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scout_pos->x += total_dist*cos(-theta); |
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scout_pos->y -= total_dist*sin(-theta); |
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scout_pos->theta = fmod(theta, (float)(2*M_PI)); |
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//Save state for next time in.
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motor_fl_ticks = scout_enc.fl_ticks; |
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motor_fr_ticks = scout_enc.fr_ticks; |
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motor_bl_ticks = scout_enc.bl_ticks; |
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motor_br_ticks = scout_enc.br_ticks; |
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return;
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} |
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void Odometry::run()
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{ |
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scout_position = node.advertise< ::messages::ScoutPosition>(name+"/position", 1000); |
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while(ok())
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{ |
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get_position(); |
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position.name = name; |
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position.x = scout_pos->x; |
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position.y = scout_pos->y; |
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position.theta = scout_pos->theta; |
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scout_position.publish(position); |
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} |
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} |