root / scout / libscout / src / behaviors / Odometry.cpp @ 751d4f4f
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1 | f79fbce2 | Priya | |
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2 | #include "Odometry.h" |
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3 | |||
4 | using namespace std; |
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5 | |||
6 | /** Set up the odometry node and prepare communcations over ROS */
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7 | 751d4f4f | Alex | Odometry::Odometry(string scoutname, Sensors* sensors)
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8 | : Behavior(scoutname, "odometry", sensors)
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9 | { |
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10 | name = scoutname; |
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11 | scout_pos = new pos;
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12 | motor_fl_ticks = motor_fr_ticks = motor_bl_ticks = motor_br_ticks = 0;
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13 | } |
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14 | |||
15 | /** Set up the odometry node and prepare communcations over ROS */
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16 | Odometry::Odometry(string scoutname, string behavior_name, Sensors* sensors) |
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17 | : Behavior(scoutname, behavior_name, sensors) |
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18 | f79fbce2 | Priya | { |
19 | 30a3768e | Priya | name = scoutname; |
20 | f79fbce2 | Priya | scout_pos = new pos;
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21 | 3db79f25 | Priya | motor_fl_ticks = motor_fr_ticks = motor_bl_ticks = motor_br_ticks = 0;
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22 | f79fbce2 | Priya | } |
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24 | /** Query encoders and estimate position based on encoder reading */
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25 | void Odometry::get_position()
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26 | { |
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27 | float left_dist, right_dist, total_dist, theta;
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28 | |||
29 | encoder_readings scout_enc = encoders->query(); |
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30 | 31be19a6 | Priya | motor_fl_dist = scout_enc.fl_ticks - motor_fl_ticks; |
31 | motor_fr_dist = scout_enc.fr_ticks - motor_fr_ticks; |
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32 | motor_bl_dist = scout_enc.bl_ticks - motor_bl_ticks; |
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33 | motor_br_dist = scout_enc.br_ticks - motor_br_ticks; |
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34 | f79fbce2 | Priya | |
35 | 3db79f25 | Priya | // Get Left and Right distance
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36 | left_dist = DIST_PER_TICK*(((float)(motor_fl_dist))/2.0 + |
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37 | ((float)(motor_bl_dist))/2.0); |
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38 | right_dist = DIST_PER_TICK*(((float)(motor_fr_dist))/2.0 + |
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39 | ((float)(motor_br_dist))/2.0); |
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40 | f79fbce2 | Priya | |
41 | 3db79f25 | Priya | total_dist = (left_dist)/2.0 + (right_dist)/2.0; |
42 | ddfeb111 | Priya | theta = scout_pos->theta + atan2(right_dist - left_dist, WHEEL_BASE); |
43 | |||
44 | //Use negative theta because we measure theta from 0 on the
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45 | //right to 180 on the left counter-clock-wise, but this is
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46 | //negative theta in the coordinate frame.
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47 | //Also, subtract the delta from y because positive y is down.
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48 | scout_pos->x += total_dist*cos(-theta); |
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49 | scout_pos->y -= total_dist*sin(-theta); |
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50 | 339f64d2 | Alex | scout_pos->theta = fmod(theta, (float)(2*M_PI)); |
51 | 31be19a6 | Priya | |
52 | //Save state for next time in.
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53 | motor_fl_ticks = scout_enc.fl_ticks; |
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54 | motor_fr_ticks = scout_enc.fr_ticks; |
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55 | motor_bl_ticks = scout_enc.bl_ticks; |
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56 | motor_br_ticks = scout_enc.br_ticks; |
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57 | 3db79f25 | Priya | |
58 | |||
59 | f79fbce2 | Priya | return;
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60 | } |
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61 | |||
62 | void Odometry::run()
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63 | { |
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64 | 30a3768e | Priya | scout_position = node.advertise< ::messages::ScoutPosition>(name+"/position", 1000); |
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66 | f79fbce2 | Priya | while(ok())
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67 | { |
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68 | get_position(); |
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69 | 30a3768e | Priya | |
70 | position.name = name; |
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71 | position.x = scout_pos->x; |
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72 | position.y = scout_pos->y; |
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73 | position.theta = scout_pos->theta; |
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74 | scout_position.publish(position); |
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75 | f79fbce2 | Priya | } |
76 | } |