Only released in EOL distros:   groovy hydro indigo kinetic

Overview

This controller for the Barrett Hand is a python node based on the original library pyHand. By using this controller it will be able to set the position or velocity of the motorized joints of the hand and read from all of its sensors (fingertip torque and tactile sensors, temperature) and joint positions.

Configuration

launch file

<?xml version="1.0"?>
<launch>
 
  <node pkg="bhand_controller" type="bhand_node.py" name="bhand_node" output="screen">
      <rosparam command="load" file="$(find bhand_controller)/config/bhand.yaml" />
      <param name="topic_state" value="state" />
      <param name="port" value="/dev/pcanusb0" />
      <param name="tactile_sensors" value="True" />
  </node>
 
</launch>

• topic_state: Name of the topic to publish the state.
• port: can device connected to the hand.
• tactile_sensors: Flag to set if the tactile sensors are available and want to be published.

config file

# Joint ids (don't modify) 
joint_ids: [ F1, F1_TIP, F2, F2_TIP, F3, F3_TIP, SPREAD_1, SPREAD_2]
# Joint names associated with the ids
joint_names: [bh_j12_joint, bh_j13_joint, bh_j22_joint, bh_j23_joint, bh_j32_joint, bh_j33_joint, bh_j11_joint, bh_j21_joint]
# Default control mode
control_mode: POSITION
# Desired freq
desired_freq: 250.0

• joint_ids: ID associated with every joint
• joint_names: Joint names associated with every joint id
• control_mode: Default hand control mode
• desired_freq: Desired frequency of the controller's control loop. A frequency higher than 300 Hz is not recommendable for now.

Topics

Published

state

• General state of the hand.

• Type: bhand_controller/State.msg

• Example:

  state: 300
  control_mode: VELOCITY
  hand_initialized: True
  desired_freq: 250.0
  real_freq: 246.000228882
  state_description: READY_STATE
  temp_f1: [37.0, 58.0]
  temp_f2: [36.0, 60.0]
  temp_f3: [35.0, 54.0]
  temp_spread: [30.0, 62.0]

tact_array

• Values from BHand tactile array
• Unit: N/cm2

• Type: bhand_controller/TactileArray.msg

• Example:

  header: 
    seq: 15277
    stamp: 
      secs: 1408685936
      nsecs: 928946018
    frame_id: ''
  finger1: [0.09000000357627869, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.019999999552965164, 0.009999999776482582, 0.0, 0.009999999776482582, 0.0, 0.0, 0.019999999552965164, 0.0, 0.03999999910593033, 0.0]
  finger2: [0.0, 0.019999999552965164, 0.0, 0.03999999910593033, 0.029999999329447746, 0.029999999329447746, 0.019999999552965164, 0.019999999552965164, 0.029999999329447746, 0.019999999552965164, 0.019999999552965164, 0.019999999552965164, 0.029999999329447746, 0.029999999329447746, 0.07000000029802322, 0.09000000357627869, 0.0, 0.09000000357627869, 0.009999999776482582, 0.019999999552965164, 0.05999999865889549, 0.009999999776482582, 0.0, 0.03999999910593033]
  finger3: [0.0, 0.0, 0.0, 0.0, 0.019999999552965164, 0.029999999329447746, 0.0, 0.0, 0.019999999552965164, 0.0, 0.009999999776482582, 0.029999999329447746, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.019999999552965164, 0.0, 0.0, 0.0]
  palm: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]

joint_states

• Joint states of the hand.

• Type: sensor_msgs/JointState.msg

• Fingertip torque sensors are published in effort field (N/m)

• Example:

  header: 
    seq: 4912
    stamp: 
      secs: 1408685894
      nsecs: 728996992
    frame_id: ''
  name: ['bh_j23_joint', 'bh_j12_joint', 'bh_j22_joint', 'bh_j32_joint', 'bh_j33_joint', 'bh_j13_joint', 'bh_j11_joint', 'bh_j21_joint']
  position: [0.0, 0.0, 0.0, -0.0, 0.0, 0.0, 0.0, 0.0]
  velocity: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
  effort: [0.03743090386539949, 0.06140198104320094, 0.03743090386539949, 0.06676343437499943, 0.06676343437499943, 0.06140198104320094, 0.0, 0.0]

  

Subscribed

command

• Sets the position/velocity of the hand joints.
• Joints available to set positions/velocities:

  • bh_j32_joint -> F3-Base

  • bh_j11_joint -> F1-Spread

  • bh_j12_joint -> F1-Base

  • bh_j21_joint -> F2-Spread

  • bh_j22_joint -> F2-Base

  • bh_j11_joint and bh_j21_joint set the same motor (able publishing on both)

• Type: sensor_msgs/JointState.msg

• Example:

  $ rostopic pub /bhand_node/command sensor_msgs/JointState "header:
    seq: 0
    stamp: {secs: 0, nsecs: 0}
    frame_id: ''
  name: ['bh_j11_joint', 'bh_j32_joint', 'bh_j12_joint', 'bh_j22_joint']
  position: [0 , 0, 0, 0]
  velocity: [0]
  effort: [0]"

Services

Server

actions

• Performs specific actions and movements (see bhand_controller/Service.msg)

• Type: bhand_controller/Actions.srv

• Example:

  $ rosservice call /bhand_node/actions "action: 1"  (Inits the hand)

set_control_mode

• Sets the control mode in position or velocity

• Type: bhand_controller/SetControlMode.srv

• Example:

  $ rosservice call /bhand_node/set_control_mode "mode: 'VELOCITY'"