5GRobot_WSG50

The gripper is currently set to operate with DHCP, the MAC-address is: 00:50:c2:cf:20:36 The IP-address will be set to XX.XX.XX.21 on deployment.

Command protocol

The gripper follows a bespoke command protocol. A ROS-package is being drafted to give access to this, but a short primer follows. For deeper reference, refer to - 5GRobot_WSG50/WSG50_Command_Set_Reference_Manual.pdf

Data transmissio is based on little endian representation of multibyte words - 0x1234 is transmitted as 0x34 0x12. Float values are represented by a 4-byte IEEE 754 single precision number. D31 - Sign D30..23 - Exponent D22..0 - Mantissa

Packet Structure

Packets generally have the following structure:

[0xAA 0xAA 0xAA]	[0xXX]	[0xXX 0x00]	[0xXX .. 0xXX]	[0xXX 0xXX]
3-byte preamble (always AA AA AA)	1-byte Command ID	2-byte Size (little endian)	N-byte Payload	2-byte checksum

Commands Used

Command	Code	Parameters
Preposition Gripper	0x21	B0 - Flag Bits D7..2 Unused (set to 0) D1 - Stop on Block: stop (1) or clamp (0) on block D0 - Movement Type: relative (1) or absolute to closed fingers (0) B1..4 - Width (mm) B5..8 - Speed (mm/s)
Grasp Part	0x25	B0..3 - Part Width (mm) B4..7 - Speed (mm/s)
Release Part	0x26	B0..3 - Open Width (mm) B4..7 - Speed (mm/s)
Disconnect Announcement	0x07	None
Ack Fault Condition	0x24	B0..2 - Ack key (String containing 'ack' = 0x61 0x63 0x6B)
Get System State (WIP)	0x40	Sent Parameters: B0 - Flag Bits D7..2 Unused (set to 0) D1 - Change-Sensitive Update: Update on change (1) or always (0) D0 - Automatic Update: enabled (1) or disabled (0) B1..2 - Period between auto-sent packets (ms) Returned Parameters: B0..3 - Bit Vector (for definition see Command Set Reference Manual Appendix B)

---

Running the ROS2 Package in Docker

For ease of use the package has been implemented in docker and can be added to a docker-compose file or run from it's own docker-compose file. Firstly, the repository has to be cloned into a desired folder

$ git clone https://github.com/AAU-RoboticsAutomationGroup/5GRobot_WSG50.git

Once the repository has been downloaded, enter the docker folder.

$ cd 5GRobot_WSG50/docker

Then simply build the container and run it.

$ docker-compose build

$ docker-compose up

If the gripper is connected the fingers should move into the home position(open). The ros2 package will log if this is done successfuly or not. The package will create a set of topics that can be used to control the gripper. These can be found in the list below.

	Description	Message Type	Structure & Units
/wsg50/connect	Starts a TCP/IP connection to the WSG50 gripper	std_msgs.msg/Empty
/wsg50/disconnect	Ends a TCP/IP connection to the WSG50 gripper	std_msgs.msg/Empty
/wsg50/preposition	Moves the fingers into position for grasping	interface_wsg.msg/MoveFingers	float64 width [mm], float64 speed [mm/s]
/wsg50/grasp	Closes the fingers around a part.	interface_wsg.msg/MoveFingers	float64 width [mm], float64 speed [mm/s]
/wsg50/release	Releases a previously grasped part.	interface_wsg.msg/MoveFingers	float64 width [mm], float64 speed [mm/s]
/wsg50/gripper_state	Gets the state of the gripper(see Appendix B in the command set reference manual)	interface_wsg.msg/GripperState	std_msgs/Header header, string[] state_flags, float64 gripper_width [mm]

---

Problems & Solutions

Solutions to known problems will be posted below for now.

docker-compose permission issues

There are sometimes permission issues with running docker-compose. Run the following commands in a terminal to ensure the permissions are the place:

$ sudo groupadd docker

$ sudo usermod -aG docker $USER

$ newgrp docker