ubiquity_motor

Introduction

This is a Package that provides a ROS interface for the motors in UbiquityRobotics robots. It communicates with the motor controller via a serial port.

Installation

This package may be installed from binaries for both x86 and ARM architectures.

The package may be installed with:

sudo apt-get install ros-kinetic-ubiquity-motor

Configuration launch files for the Magni robot are in the package magni_robot.

ROS API

Subscribed topics

cmd_vel geometry_msgs/Twist The command input.

Published topics

odom nav_msgs/Odometry Odometry computed from motor controller messages.

/tf tf/tfMessage The transform from odom to base_link

battery_state sensor_msgs/BatteryState Charge state of the robot’s batteries.

publish_cmd geometry_msgs/TwistStamped The value of cmd_vel after limits were applied. Available if the publish_cmd paramater is set.

Parameters

Comms paramaters

serial_port (string, default: “/dev/ttyS0”) Name of device with which to communicate with motor controller hardware.

baud_rate (int, default: 9600) Baud rate for serial communication with motor controller hardware.

Firmware parameters

pid_proportional (int, default: 5000) The P paramater for the motor controller’s PID controller.

pid_integral (int, default: 10) The I paramater for the motor controller’s PID controller.

pid_derivative (int, default: 1) The D paramater for the motor controller’s PID controller.

pid_denominator (int, default: 1000) Divisor for the above PID paramaters.

pid_moving_buffer_size (int, default: 10) Size of a moving buffer used in the control loop.

deadman_timer (int, default: 2400000) If a message is not received after this interval (in MCU clock ticks), the motor controller should assume an error condition and stop.

battery_voltage_multiplier (float, default: 0.5185) Used to calculate battery voltage from motor controller messages.

battery_voltage_offset (float, default: 0.40948) Used to calculate battery voltage from motor controller messages.

Node parameters

controller_loop_rate (double, default: 20.0) Rate (in Hz) at which to send commands to the motor controller hardware.

diff_drive_controller paramaters

left_wheel (string | string[…]) Left wheel joint name or list of joint names.

right_wheel (string | string[…]) Right wheel joint name or list of joint names.

pose_covariance_diagonal (double[6]) Diagonal of the covariance matrix for odometry pose publishing.

twist_covariance_diagonal (double[6]) Diagonal of the covariance matrix for odometry twist publishing.

publish_rate (double, default: 50.0) Frequency (in Hz) at which the odometry is published. Used for both tf and odom.

wheel_separation_multiplier (double, default: 1.0) Multiplier applied to the wheel separation parameter. This is used to account for a difference between the robot model and a real robot.

wheel_radius_multiplier (double, default: 1.0)

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Changelog for package ubiquity_motor

0.9.0 (2019-04-03)

• Allow selecting what firmware version to download
• Adding max motor forward and reverse speeds and max pwm settings all the way from ROS parameters to being pushed to the controller board.
• Analyze information to create diagnostics statuses
• Major update to test_motor_board.py that accepts greatly improved parameter read and set as well as ability to specify com port device to be used
• Adds support for set of hw rev and for pre rev 5.0 estop threshold
• Contributors: Mark Johnston, Rohan Agrawal

0.8.0 (2019-01-01)

• Added firmware loading tool
• Added misc testing scripts
• Don't die when communication not working, only print error
• Use std mutex/atomic instead of boost
• Reduce print level on integral/pid limits
• Contributors: Rohan Agrawal

0.7.1 (2018-06-16)

• new pid params
• Contributors: Rohan Agrawal

0.7.0 (2018-04-15)

• Add script to probe the robot for information
• Add Serial Protocol Documentation Fixes #33
• Add ROS API documentation (#32)
  • Add API documentation
  • Remove unused serial_loop_rate variable
• Contributors: Jim Vaughan, Rohan Agrawal

0.6.1 (2017-11-12)

• Reset controller when time jumps (#31) Reset the controller and zero commanded velocity an unexpected time change occurs (such as by NTP). This prevents unexpected robot motion.
• Contributors: Jim Vaughan, Rohan Agrawal

0.6.0 (2017-09-15)

• Publish battery voltage messages (#29) Added battery status message calibrated on 4.4 board serial no 450
• Contributors: Jim Vaughan, Rohan Agrawal, David Crawley

0.5.2 (2017-05-06)

• Remove debug topics (#25)
  • Remove debug topics
  • Remove tests of debug registers
• Merge pull request #22 from UbiquityRobotics/suppresserrorsatstartup Supress some potentially confusing warnings
• Increase error_threshold
• Merge pull request #23 from UbiquityRobotics/fix_acceleration_limits Fix computaion of elapsed time so that it is +ve
• Fix computaion of elapsed time so that it is +ve
• Supress some potentially confusing warnings
• Clean out serial loop (#20)
  • Transmit the the same thread caller, not in serial thread
  • go back to debug on tranmissions
  • Use smarter waits and reads in reading thread
  • Get rid of serial loop rate
  • Reformat
• Contributors: Jim Vaughan, Rohan Agrawal

0.5.1 (2017-03-04)

• Reduce flakey-ness of the tests
• Try to get firmware version, throw after 10 tries
• Code cleanup
• Use fixed sized arrays (not vectors) where they make sense
• Use a seperate shared_queue class
• Performance improvements
• Contributors: Rohan Agrawal

0.5.0 (2016-09-04)

• NOTE: This version drops support for firmware versions before 24
• Use new 8-byte serial protocol
• Add support for using dynamic_reconfigure to change PID parameters
• Add support for setting the deadman timer via a parameter
• Add support for debug registers, do enable better firmware diagnostics
• Add support for limit reached warnings from firmware

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