This is some standalone code to communicate with the Schunk PowerBall LWA4P arm and CommonplaceRobotics force-torque sensor (FTS).
Schunk and CommonplaceRobotics also provide example applications and utilities
which can be used in Windows. See included media (CDROM disks) and search
http://robots.mobilerobots.com for more information. In particular the Schunk
LWA_Tool program available in the CANopen Tools packages from Schunk
can be used to test the arm and display lots of diagnostic information. (It
requires installing the ESD USB-CAN driver for Windows first.)
The code repository is published at http://github.com/MobileRobots/libPowerballArm. To make and share changes, you can create a fork of that repository and submit pull requests or discuss changes on the aria-users mailing list.
It is based on code from the ipa_canopen ROS node
https://github.com/ipa320/ipa_canopen, with some modifications to use
SocketCAN instead of the proprietary Peak pcan driver. ipa_canopen
was written by Thiago de Freitas, Tobias Sing, Eduard Herkel and others
at Fraunhofer Institute for Manufacturing Engineering and Automation
(IPA Fraunhofer). This was chosen because it is the simplest/smallest
open source partial-CanOPEN implementation specifically intended for
use with the Schunk LWA4P arm that was easily available as of
October 2015. This may be replaced by another CanOPEN implementation,
or the whole libPowerballArm library may be replaced by a more complete
Powerball/CanOPEN-based arm interface, in the future. Notices of
changes or updates will be made at http://robots.mobilerobots.com,
the aria-users mailing list, and/or at http://github.com/MobileRobots/libPowerballArm.
The Boost thread and system development libraries are requited to build. Boost-system is required at runtime. To install these on Ubuntu or Debian to build,
sudo apt-get install libboost-thread-dev libboost-system-dev
To build or rebuild the library and example programs, use make:
make
To enable some debugging output in the canopen library edit src/ipa_canopen_core.cpp
and change the definition of the DEBUG symbol to true, then rebuild.
This library also includes an interface for the CPR Force-Torque Sensor for Schunk LWA arms (called FTS-LWA or FTL in some documentation).
This library relies on Linux kernel CAN support (SocketCAN), i.e. the
can0 socket interface must be available through Linux.
A Linux kernel module driver must be loaded for your specific CAN adapter. For example, to load the driver for a Peak Systems USB-CAN adapter:
sudo modprobe peak_usb
Or for an ESD CAN-USB adapter:
sudo modprobe esd_usb2
Run dmesg for Linux log messages. You can list the name of the module in
/etc/modules to automatically load at boot.
See http://robots.mobilerobots.com/wiki/Linux_SocketCAN for information on
SocketCAN including how to configure the CAN interface(s) using the Linux
ip command. To bring up the first CAN interface up, use these commands:
sudo ip link set can0 type can bitrate 500000 sudo ip link set up can0
The Schunk LWA4P arm and FTS-LWA force-torque sensor both use bitrates of 500000 (500K) on the CAN bus.
To bring up a second CAN interface (e.g. force-torque sensor or hand):
sudo ip link set can1 type can bitrate 500000 sudo ip link set up can1
You can put these commands in /etc/rc.local to run when the system boots up.
can0 will be the device plugged into a prior USB port (e.g. USB port
labelled "J2" on a Mamba onboard computer), and can1 will be the later
USB port (e.g. USB port labelled "J3" on a Mamba onboard computer). You
can list USB devices on Linux with the command lsusb -t, e.g.:
lsusb -t
It will show USB CAN interfaces in the order they are attached to USB.
For example, two ESD CAN-USB interfaces attached to J2 and J3 on a Mamba
onboard computer will be listed in the output of lsusb -t like this:
/: Bus 02.Port 1: Dev 1, Class=root_hub, Driver=ehci_hcd/8p, 480M
|__ Port 1: Dev 2, If 0, Class=vend., Driver=esd_usb2, 480M
|__ Port 3: Dev 3, If 0, Class=vend., Driver=esd_usb2, 480M
The library defaults to expecting the arm to be on can0, and the FTS to be on a second CAN bus, can1. Alternate interfaces can be specified in the API.
It has been teasted with the ESD USB-CAN adapter (esdcan Linux driver module)
and Peak USB-CAN adapter (pcan_usb Linux driver module).
Some simple example programs are available in the examples directory.
Each motor in the Powerball arm has a CAN device ID, starting at 3. The final joint (wrist rotation) is 8. The gripper is device id 12.
ERB module (ball) Motor axis CAN node ID
--------------------------------------------------
base rotation 0x3
base pivot 0x4
middle (elbow) pivot 0x5
middle (elbow) rotation 0x6
end (wrist) pivot 0x7
end (wrist) rotation 0x8
The ipa_canpen_core library is capable of moving arm motor axis modules using the
"interpolated position" mode. Starting at the arm modules's current position,
new positions are sent to the device according to a desired velocity.
ipa_canopen_core automatically increments the position and sends
the new position to the arm in the background. Your program must initiate
a "sync" message which, when received by the module, causes it to start
or continue moving towards the next position. If no sync messages are
sent the module times out and stops.
When installed on a Seekur Jr. robot, the arm is powered by switched
24V power supplies of Seekur Jr. (Arm motor power on port #29 and arm logic power
port #8). These need to be switched on to use the arm. Arm modules may enter
a fault state in which power supplied them from the arm base is switched off,
or another fault state in which power needs to be reset. To do that switch
off and on or reset these Seekur Jr. power supplies using the seekurPower
command, e.g.
seekurPower -29 reset -8 reset
This code is distributed under the terms of the GNU Lesser General Public License (LGPL). See the LICENSE file for full license details.
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
- Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
- Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
- Neither the name of the Fraunhofer Institute for Manufacturing
Engineering and Automation (IPA) nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.
This program is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License LGPL as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License LGPL for more details.
You should have received a copy of the GNU Lesser General Public License LGPL along with this program. If not, see http://www.gnu.org/licenses/.