fidi robot

a robot based on Lego 42065 Tracked Racer and the Beaglbone Blue

Using various nodes:

Nodes overview

• differential driver node using the onboard motor ports
• publisher for IMU messages from MPU9250
• range sensor vl53l0x_driver
• for basic navigation move_basic package by UbiquityRobotics

launch

roslaunch fidi_robot fidi.launch

• loads model urdf/model.urdf
• creates static transform base_link -> imu_link
• launches vl53l0x_driver
• launches IMU node

Differential Motor Driver

Max speed(linear velocity): 0,364 m/s @ duty cycle 0,8 (to not overload the motor controller with the Lego PF L motors)

Max angular velocity based on max speed: 5,6 rad/s @ 0,364 m/s and wheelbase 0,13

Parameter

• ~left_motor = 3
• ~right_motor = 4
• ~timeout = 5
• ~maxspeed = 0.364
• ~minspeed = 0.137
• ~wheelbase = 0.13
• ~turnspeed = 1
• ~duty_factor = 1

Run

rosrun bbblue_drivers diff_motor_driver _left_motor:=3 _right_motor:=4 _minspeed:=0.137 _maxspeed:=0.364 _duty_factor:=2.2 _wheelbase:=0.17

Publish to cmd_vel manually

rostopic pub -1 /cmd_vel geometry_msgs/Twist -- '[1.0, 0.0, 0.0]' '[0.0, 0.0, 0]'

Basic Navigation (move_basic)

Run

rosrun move_basic move_basic _min_angular_velocity:=2.8 _max_angular_velocity:=10

Publish simple navigation target

180 degree turn

rostopic pub -1 /move_base_simple/goal geometry_msgs/PoseStamped "header:
  seq: 1
  stamp:
    secs: 0
    nsecs: 0
  frame_id: 'base_link'
pose:
  position:
    x: 0.0
    y: 0
    z: 0.0
  orientation:
    x: 0.0
    y: 0.0
    z: 1
    w: 0.0 "

Joystic control

https://kofler.info/bluetooth-konfiguration-im-terminal-mit-bluetoothctl/ bluetoothctl scan on pair trust connect

sudo apt install ros-melodic-joy ros-melodic-teleop-twist-joy

http://wiki.ros.org/joy/Tutorials/ConfiguringALinuxJoystick rosparam set joy_node/dev "/dev/input/js0"

rosrun joy joy_node

http://wiki.ros.org/teleop_twist_joy nintendo joy-con (L) rosrun teleop_twist_joy teleop_node _axis_linear:=4 _axis_angular:=5 _scale_angular:=3 _enable_button:=15

Visualizing rviz

The Beaglebone Blue has no display port. So for visualization an aditional system is required.

export ROS_MASTER_URI=http://beaglebone:11311

Starting rviz after exporting the MASTER

rviz has issues with other localizations. (no model shown) export LC_NUMERIC="en_US.UTF-8"

rviz

red - x green - y blue -z