allegro_hand_ros

Allegro Hand ROS

This is a fork of the official release to control Allegro Hand with ROS Kinetic : https://github.com/simlabrobotics/allegro_hand_ros_v4. This repo has been heavily modified in order to :

• Patch some tremendous errors (e.g the velocity computation)
• Simplify it
• Follow ROS standard and making it compatible with ros_control
• Provide a simulator that replicate the real robot behavior, using Gazebo (using previous point).

Note: The repo inria-paris-robotics-lab/allegro_hand_hardware_v4 contains CAD files for mounting the Allegro Hand on a UR5 arm.

Launch file instructions:

There is now a single file, allegro_hand.launch that starts the hand. It takes many arguments, but at a minimum you must specify the handedness:

roslaunch allegro_hand_controllers allegro_hand.launch CHIRALITY:=right

Optional (recommended) arguments:

      RESPAWN:=true|false   Respawn controller if it dies.
      AUTO_CAN:=true|false  (default is true)
      CAN_DEVICE:=/dev/pcanusb1 | /dev/pcanusbNNN  (ls -l /dev/pcan* to see open CAN devices)
      VISUALIZE:=true|false  (Launch rviz)
      GAZEBO:= true|false  To use the simulation or the real robot

Note on AUTO_CAN: The script detect_pcan.py will automatically finds an open /dev/pcanusb file. If instead you specify the can device manually (CAN_DEVICE:=/dev/pcanusbN), make sure you also specify AUTO_CAN:=false. Obviously, automatic detection cannot work with two hands.

The second launch file is for visualization, it is included in allegro_hand.launch if VISUALIZE:=true. Otherwise, it can be useful to run it separately (with VISUALIZE:=false), for example if you want to start rviz separately (and keep it running):

roslaunch allegro_hand_controllers allegro_viz.launch CHIRALITY:=right

Packages and installation

• allegro_hand Contains launchfiles to start everything easily.
• allegro_hand_driver Driver for talking with the allegro hand.
• allegro_hand_controllers Expose the allegro hand to be compatible with ros_control.
• allegro_hand_description xacro descriptions for the kinematics of the hand, rviz configuration and meshes.
• allegro_hand_ros_v4 Empty meta-package to compile all the above package conveniently (i.e. catkin build allegro_hand_ros_v4 build all of them).

Note: If you intend to use this package in simulation only (with gazebo), it is recommended to add allegro_hand_driver and allegro_hand_controllers in your catkin --skiplist. They are useless for the simulation and require hardware related libraries to be installed manually... (if your are using catkin --buildlist you can, likewise, only add allegro_hand_description package to the list).

catkin config --skiplist <packages already in the skiplist> allegro_hand_controllers allegro_hand_driver

Note on polling (from Wonik Robotics): The preferred sampling method is utilizing the Hand's own real time clock running @ 333Hz by polling the CAN communication. In fact, ROS's interrupt/sleep combination might cause instability in CAN communication resulting unstable hand motions.

Useful Links

• Allegro Hand wiki.

Controlling More Than One Hand

When running more than one hand using ROS, you must specify the number of the hand when launching.

roslaunch allegro_hand.launch CHIRALITY:=right CAN_DEVICE:=/dev/pcan0 AUTO_CAN:=false

roslaunch allegro_hand.launch CHIRALITY:=left CAN_DEVICE:=/dev/pcan1 AUTO_CAN:=false

Known Issues:

While all parameters defining the hand's motor/encoder directions and offsets fall under the enumerated "allegroHand_#" namespaces, the parameter "robot_description" defining the kinematic structure and joint limits remains global. When launching a second hand, this parameter is overwritten. A fix must be found when the problem will occur.

Installing the PCAN driver (for using the real robot only)

Note: It is recommended to not follow this section of the tutorial if you do not intend to control the real Allegro Hand robot with your machine.

Before using the hand, you must install the pcan drivers. This assumes you have a peak-systems pcan to usb (or pcan to PCI) adapter.

1. Install these packages

   sudo apt-get install libpopt-dev ros-kinetic-libpcan

2. Download latest drivers: http://www.peak-system.com/fileadmin/media/linux/index.htm#download

Install the drivers:

make clean; make NET=NO_NETDEV_SUPPORT
sudo make install
sudo /sbin/modprobe pcan

Test that the interface is installed properly with:

 cat /proc/pcan

You should see some stuff streaming.

When the hand is connected, you should see pcanusb0 or pcanusb1 in the list of available interfaces:

ls -l /dev/pcan*

If you do not see any available files, you may need to run:

sudo ./driver/pcan_make_devices 2

from the downloaded pcan folder: this theoretically creates the devices files if the system has not done it automatically.

3. Build the sources

    catkin build
    source devel/setup.bash

4. quick start

    roslaunch allegro_hand.launch GAZEBO:=True CHIRALITY:=right
    # Or
    roslaunch example_wave.launch