Motor Controller Rewrite
Contents
Source Code
TBD - code is in flux
Build
Additions to ~/catkin_ws_indigo/src/phidgets_cat/CMakeList.txt
# motor_control_hc_nav add_executable(motor_control_hc_nav src/motor_control_hc_nav.cpp) target_link_libraries(motor_control_hc_nav ${catkin_LIBRARIES} phidget21 )
Launch Script
Launch script in floor_hugger/launch/motor_control_nav.launch
<launch> <node pkg="phidgets_cat" type="motor_control_hc_nav" name="motor_control_hc_nav" respawn="true" output="screen"> <param name="odometry" value="/odom" /> <param name="wheelbase" value="305" /> <param name="pid_proportional" value="15" /> <param name="pid_integral" value="60" /> <param name="pid_derivative" value="0" /> </node> </launch>
Test Execution
Terminal 2
The motor_control_nav launch script executes the code associated with the motor_control_hc_nav.cpp code in the phidgets_cat package.
roslaunch floor_hugger motor_control_nav.launch
Terminal 3
roslaunch floor_hugger odometry.launch
Terminal 4
Take the place of the navigation stack by publishing a cmd_vel message of type Twist. It has linear.x value of 0.20 m/sec and an angular.z value of 0.1 radians/sec.
roscd floor_hugger/test/ python motors_go_full.py 0.20 0.1
motors_go_full.py <linear.x> <angular.z>
Terminal 5
Monitor resulting motor status with one of the following
rostopic echo odom rqt_plot /cmd_vel/linear/x /odom/twist/twist/linear/x /odom/twist/twist/linear/y
Results Without PID
Odometry is not steady. This is the results of the printout from:
ROS_INFO ("linear x cmd_vel %.3f odom %.3f", m.linear.x, odom.twist.twist.linear.x);
The requested linear.x was 0.37 m/sec. Notice that the resulting x speed varied from about 0.31 to 0.39 or roughly 20%. The disturbing results are periodic values of 0. They occur at rotation quadrant boundaries.
[ INFO] [1498936142.530818061]: linear x cmd_vel -0.370 odom -0.324 [ INFO] [1498936142.630888175]: linear x cmd_vel -0.370 odom -0.381 [ INFO] [1498936142.730873989]: linear x cmd_vel -0.370 odom -0.378 [ INFO] [1498936142.830848798]: linear x cmd_vel -0.370 odom 0.000 [ INFO] [1498936142.930902163]: linear x cmd_vel -0.370 odom -0.360 [ INFO] [1498936143.030857096]: linear x cmd_vel -0.370 odom -0.360 [ INFO] [1498936143.130885123]: linear x cmd_vel -0.370 odom -0.319 [ INFO] [1498936143.230823537]: linear x cmd_vel -0.370 odom -0.317 [ INFO] [1498936143.330835216]: linear x cmd_vel -0.370 odom -0.388 ...
Resolution Investigations
- This appears to be an odometry (not motor controller) issue. See odometry.cpp in the Phidgets package.
- Include PID and tune. See