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Laser Scanner Trajectory Controller

Introduction

This controller allows you to send periodic/repeating command to the tilting laser on the PR2

ROS API

Parameters

joint (string, default: Required)

• The joint to control

gains/p (double, default: Required)

• The position gain

gains/d (double, default: 0.0)

• The position derivative gain

gains/i (double, default: 0.0)

• The integral gain around position

gains/i_clamp (double, default: 0.0)

• The clamp of the integral gain

velocity_filter (Filter Chain, default: Required)

• namespace defining a filter chain acting on the measured velocity. Refer to Filter Chain for more details

max_velocity (double, default: Required)

• Maximum allowed velocity/rate for a trajectory that this controller generates (in rad/sec)

max_acceleration (double, default: Required)

• Maximum allowed acceleration for a trajectory that this controller generates (in rad/sec^2)

Example Configuration:

laser_tilt_controller:
  type: LaserScannerTrajController
  joint: laser_tilt_mount_joint
  gains:
    p: 8.0
    i: 0.1
    d: 0.2
    i_clamp: 0.5
  velocity_filter:
    - name: low_pass
      type: TransferFunctionFilterDouble
      params:
        a: [1.0, -0.1]
        b: [0.9]
  max_velocity:    100
  max_acceleration: 30

Published Topics

<name>/laser_scanner_signal (pr2_msgs/LaserScannerSignal)

• The index of the last completed trajectory segment. Useful for aggregating laser scans

Subscribed Topics

<name>/set_periodic_cmd (pr2_msgs/PeriodicCmd)

• Sets the periodic trajectory using periodic parameters like period, amplitude, and offset

<name>/set_traj_cmd (pr2_msgs/LaserTrajCmd)

• Sets the periodic trajectory by explicitly setting trajectory waypoints

Services

<name>/set_periodic_cmd (pr2_msgs/SetPeriodicCmd)

• Sets the periodic trajectory using periodic parameters (period, amplitude, and offset)

<name>/set_traj_cmd (pr2_msgs/SetLaserTrajCmd)

• Sets the periodic trajectory by explicitly setting trajectory waypoints (position & time pairs)

Usage example

rosservice call laser_tilt_controller/set_periodic_cmd '{ command: { header: { stamp: 0 }, profile: "linear" , period: 3 , amplitude: 1 , offset: 0 }}'