Robot Arm

Hardware: UFactory 850 — an xArm variant

SiLA server source: genericroboticarm

Docker service: robot_arm (port 50054)

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Hardware setup

The UFactory 850 is a 6-DOF collaborative robot arm used to move microtiter plates between positions on the platform (shakers, hotel, scanner, plate reader). It connects to the lab PC over Ethernet.

Default IP address: 192.168.1.202

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Running the SiLA server

The robot arm runs as a Docker service. Start it with:

docker compose up robot-arm

To connect to the real arm, set ROBOT_IP in a .env file in the project root:

ROBOT_IP=192.168.1.202

If ROBOT_IP is unset, the server starts in simulation mode — all move commands are accepted but nothing physically happens.

A web interface for the arm is available at http://localhost:8055 when the service is running.

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Configuration

Environment variable	Default	Description
PORT	50054	SiLA2 server port
HOST	0.0.0.0	Bind address
ROBOT_IP	(unset)	IP address of the physical arm. If unset, runs in simulation mode.
ROBOT_ARGS	(empty)	Extra flags passed to the server entrypoint

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VU-lab customization

The genericroboticarm package provides a generic XArmImplementation. The VU-lab subclasses it in src/openlab_vu/robot_arm/vu_lab/xarm_impl.py:

class VULabArm(XArmImplementation):
    @classmethod
    def get_name(cls) -> str:
        return "VULabArm"

    def site_to_position_identifier(self, device: str, slot: int) -> str:
        if slot > 0:
            return f"{device}_{slot}"
        else:
            return device

• get_name() sets the SiLA server name to "VULabArm" — this must match the value in sila_server_name in worker_adaption.py.
• site_to_position_identifier() maps a (device, slot) pair to a node label in the position graph. Single-slot devices use just the device name (e.g. shaker_1_d_pos_1); multi-slot devices append the slot number (e.g. hotel_1_d_pos_3).

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Position graph

The arm's reachable positions are defined in src/openlab_vu/robot_arm/new_graphs/position_graph_VULabArm.gml. This file is mounted into the container at runtime. Each node in the graph corresponds to a named position on the platform; edges define valid move paths between them.

See Lab Configuration — Position graph for details on the graph format and how to add new positions.