docs(arcor2_ur): fundamental instructions

compose-files/ur-demo/README.md

@@ -1,6 +1,8 @@
 # UR Demo
 
-To use with simulator, run:
+The UR Web API service itself is documented [here](https://github.com/robofit/arcor2/blob/master/src/python/arcor2_ur/README.md). 
+
+To use it with simulator, run:
 
 ```bash
 docker compose -f docker-compose.yml -f docker-compose.sim.yml up
@@ -10,4 +12,6 @@ For the real robot, use the following command:
 
 ```bash
 docker compose -f docker-compose.yml -f docker-compose.lab.yml up
-```
+```
+
+In both cases, it is necessary to create a program for external control in the robot. With simulator, one can access robot's interface (Polyscope) using the VNC on [http://localhost:6080/vnc.html](http://localhost:6080/vnc.html).

src/python/arcor2_ur/README.md

@@ -1,8 +1,25 @@
 # arcor2_ur
 
-Communicates over ROS 2 with Universal Robots (tested with UR5e).
+The service communicates over ROS 2 and MoveItPy with Universal Robots and provides simple REST API to control the robot and allow integration into ARCOR2.
+
+The service is tested with Ubuntu 24.04, ROS 2 Jazzy and the UR5e robot - however, it should be possible to use it with any robot supported by the [ROS 2 driver](https://github.com/UniversalRobots/Universal_Robots_ROS2_Driver/tree/main). It expects that the `ur_control.launch.py` is already running (which is handled in the [docker image](https://github.com/robofit/arcor2/blob/master/src/docker/arcor2_ur/start.sh)).
+
+## Setup
+
+- To prepare the robot, please install external control URCap using following [instructions](https://docs.ros.org/en/ros2_packages/rolling/api/ur_robot_driver/installation/install_urcap_e_series.html). When configuring it, enter server's hostname into "remote host IP". Name the program `prog.urp` - it will be automatically started by the service.
+- A real-time system is highly recommended for running the service. The easiest way is through the [Ubuntu Pro](https://documentation.ubuntu.com/pro/pro-client/enable_realtime_kernel/). 
 
 ## Environment variables
 
-- `ARCOR2_UR_URL=http://0.0.0.0:5012` - by default, the service listens on port 5012.
-- `ARCOR2_UR_DEBUG=1` - turns on debug logging.
+- `ARCOR2_UR_URL=http://0.0.0.0:5012` - by default, the service listens on port 5012 (Swagger UI can be found at e.g. [http://localhost:5012/swagger](http://localhost:5012/swagger)).
+- `ARCOR2_UR_DEBUG=1` - turns on debug logging.
+- `ARCOR2_UR_BASE_LINK=base_link` - sets base_link of the robot (the frame in which EEF coordinates are expressed).
+- `ARCOR2_UR_TOOL_LINK=tool0` - the frame representing EEF pose.
+- `ARCOR2_UR_TYPE=ur5e` - sets type of the robot.
+- `PLANNING_GROUP_NAME=ur_manipulator` - planning group which is going to be controlled by this service.
+- `ARCOR2_UR_INTERACT_WITH_DASHBOARD=true` - can be used to disable interaction with dashboard (controls brakes, starts `prog.urp`, etc.). 
+
+## Known Problems
+
+- The service crashes on `PUT /state/stop`.
+- Sometimes, calling `PUT /state/start` (which initializes robot and MoveIt) fails. Usually, the next time it works properly.