weiqiao / allegro-hand-ros

ROS package to control the SimLab Allegro Hand

allegro-hand unofficial fork

This is an unofficial fork of SimLab's allegro hand ros package.

It improves significantly upon the SimLab version by providing a catkin-ized version, simplifies the launch file structure, updates the package/node names to have a more consistent structure, improves the build process by creating a common driver, introduces an AllegroNode C++ class that reduces the amount of duplicated code. It also provides a python library that can control the hand directly.

It also provides the BHand library directly in this package (including both 32-bit and 64-bit versions, though 32-bit systems will need to update the symlink manually).

At this point no effort has been made to be backwards compatible.

Launch file instructions:

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

roslaunch allegro_hand allegro_hand.launch HAND:=right

You can also simulate the hand very easily:

roslaunch allegro_hand allegro_hand.launch HAND:=right CONTROLLER:=sim

Optional (recommended) arguments:

      NUM:=0|1|...
      ZEROS:=/path/to/zeros_file.yaml
      CONTROLLER:=grasp|pd|velsat|torque|sim
      RESPAWN:=true|false   Respawn controller if it dies.
      KEYBOARD:=true|false  (default is true)
      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)
      JSP_GUI:=true|false  (show the joint_state_publisher for *desired* joint angles)

Note on AUTO_CAN: There is a nice script detect_pcan.py which 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 allegro_viz.launch HAND:=right

Note that you should also specify the hand NUM parameter in the viz launch if the hand number is not zero.

Packages

• allegro_hand A python client that enables direct control of the hand in python code, and all generic launch files.
• allegro_hand_driver Driver for talking with the allegro hand.
• allegro_hand_controllers Different nodes that actually control the hand. The AllegroNode class handles all the generic driver comms, each class then implements computeDesiredTorque differently (and can have various topic subscribers):
  • grasp: Apply various pre-defined grasps, including gravity compensation.
  • pd: Joint space control: save and hold positions.
  • velsat: velocity saturation joint space control (supposedly experimental)
  • torque: Direct torque control.
  • sim: Just pass desired joint states through as current joint states.
• allegro_hand_description xacro descriptions for the kinematics of the hand, rviz configuration and meshes.
• allegro_hand_keyboard Node that sends the commanded grasps. All commands are available with the grasp controller, only some are available with the other controllers.
• allegro_hand_parameters All necessary parameters for loading the hand:
  • gains_pd.yaml: Controller gains for PD controller.
  • gains_velSat.yaml: Controller gains and parameters for velocity saturation controller.
  • initial_position.yaml: Home position for the hand.
  • zero.yaml: Offset and servo directions for each of the 16 joints, and some meta information about the hand.
  • zero_files/ Zero files for all hands.
• bhand Library files for the predefined grasps, available in 32 and 64 bit versions. 64 bit by default, update symlink for 32 bit.

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

Useful Links

• Allegro Hand wiki.
• ROS wiki for original package.

Installing the PCAN driver

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

1. Install these packages

   sudo apt-get install libpopt-dev ros-indigo-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.

Gazebo alpha support

Gazebo is supported in theory, thanks to inertial parameters from @trhermans. However, I have not been successful at running a physical simulation of the robot hand. I am leaving the gazebo option for others to experiment; to try it out, pass GAZEBO:=true to the launch file.

Contributions (pull requests) to fix the simulation are welcome.