Base Velocity Controller

Introduction

This controller allows you to send velocity commands to the base.

Status: REVIEWED, NOT STABLE .

ROS API

Parameters

• Maximum allowed translational velocity

• Maximum allowed rotational velocity

• Maximum allowed acceleration in X direction

• Maximum allowed acceleration in X direction

• Maximum allowed yaw acceleration

• The proportional gain on the caster steer velocity controller, vel_desired = kp_caster_steer * caster_steer_error

• If time from last command heard > timeout, the controller will stop the robot.

• rate of state publishing events

• The string names for all the caster link names on the robot separated by a space delimiter

• A correction multiplier for the radius of the wheels on the robot

• A correction multiplier for the reduction ratio for the caster rotation joint

Example Configuration:

pr2_base_controller:
  caster_names: fr_caster_rotation_link fl_caster_rotation_link bl_caster_rotation_link br_caster_rotation_link

  type: Pr2BaseController

  caster_pid_gains: &caster_pid_gains
    p: 3.0
    d: 0.0
    i: 0.1
    i_clamp: 4.0
  wheel_pid_gains: &wheel_pid_gains
    p: 3.0
    d: 0.0
    i: 0.01
    i_clamp: 0.4

  fl_caster_l_wheel_joint:
   *wheel_pid_gains
  fl_caster_r_wheel_joint:
   *wheel_pid_gains
  fr_caster_l_wheel_joint:
   *wheel_pid_gains
  fr_caster_r_wheel_joint:
   *wheel_pid_gains
  bl_caster_l_wheel_joint:
   *wheel_pid_gains
  bl_caster_r_wheel_joint:
   *wheel_pid_gains
  br_caster_l_wheel_joint:
   *wheel_pid_gains
  br_caster_r_wheel_joint:
   *wheel_pid_gains

  fr_caster_rotation_joint:
   *caster_pid_gains
  fl_caster_rotation_joint:
   *caster_pid_gains
  bl_caster_rotation_joint:
   *caster_pid_gains
  br_caster_rotation_joint:
   *caster_pid_gains

  kp_caster_steer: 80.0
  timeout: 0.2
  max_translational_acceleration: 
   x: 2.0
   y: 2.0 
  max_rotational_acceleration: 2.0
  state_publish_rate: 0.25

  max_translational_velocity: 1.0 
  max_rotational_velocity: 2.0

Published Topics

• The state of the base controller

Subscribed Topics

• Input velocity command for the base (the reference point for this command is the origin of the base link which is in the middle of the base)