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RoSys - The Robot System

RoSys provides an easy-to-use robot system. Its purpose is similar to ROS. But RoSys is fully based on modern web technologies and focusses on mobile robotics.

See full documentation at

Currently RoSys is mostly tested and developed on the Zauberzeug Robot Brain which uses Lizard for communication with motors, sensors and other peripherals. But the software architecture of RoSys also allows you to write your own modules if you prefer another industrial PC or setup.


All Python

Business logic is wired in Python while computation-heavy tasks are encapsulated through websockets or bindings.

Shared State

All code can access and manipulate a shared and typesafe state -- this does not mean it should. Good software design is still necessary. But it is much easier to do if you do not have to perform serialization all the time.

No Threading

Thanks to asyncio you can write the business logic without locks and mutex mechanisms. The running system feels like everything is happening in parallel. But each code block is executed one after another through an event queue and yields execution as soon as it waits for I/O or heavy computation. The latter is still executed in threads to not block the rest of the business logic.

Web UI

Most machines need some kind of human interaction. We made sure your robot can be operated fully off the grid with any web browser by incorporating NiceGUI. It is also possible to proxy the user interface through a gateway for remote operation.


Robot hardware is often slower than your own computer. Therefore RoSys supports a simulation mode for rapid development. To get maximum performance the current implementation does not run a full physics engine.


You can use pytest to write high-level integration tests. It is based on the above-described simulation mode and accelerates the robot's time for super fast execution.

Architecture and Features


RoSys modules basically are Python modules encapsulate certain functionality. They can hold their own state, register lifecycle hooks, run methods repeatedly and subscribe to or raise events. Most modules depend on other modules.

Lifecycle Hooks And Loops

Modules can register functions for being called on_startup or on_shutdown as well as repeatedly with a given interval.


Modules can provide events to allow coupling otherwise separated modules of the system. For example on module might read sensor data and raise an event NEW_SENSOR_DATA, without knowing of any consumers. Another module can register on NEW_SENSOR_DATA and act accordingly when being called.


RoSys provides an Automator module for running "automations". Automations are coroutines that can not only be started and stopped, but also paused and resumed, e.g. using AutomationControls.


Modules can register backup and restore methods to read and write their state to disk.

RoSys Time

If you want to delay the execution, you should invoke await rosys.sleep(seconds: float). This causes to wait until the RoSys time has elapsed the desired amount of time. In pytests the RoSys time is simulated and can advance much faster if no CPU-intensive operation is performed.

Threading And Multiprocessing

Not every piece of code is already using asyncio. The actor class provides convenience functions for IO and CPU bound work.

IO Bound: If you need to read from an external device or use a non-async HTTP library like requests, you should wrap the code in a function and await it with await

CPU Bound: If you need to do some heavy computation and want to spawn another process, you should wrap the code in a function and await it with await


Python is fast enough for most high level logic, but has no realtime guarantees. Safety-relevant behavior should therefore be written in Lizard and executed on a suitable microprocessor. The microprocessor governs the hardware of the robot and must be able to perform safety actions like triggering emergency hold etc. We suggest you use an industrial PC with an integrated controller like the Zauberzeug Robot Brain. It provides a Linux system with AI acceleration to run RoSys, two integrated ESP32 to run Lizard and six I/O sockets with up to 24 GPIOs for digital I/Os, CAN, RS485, SPI, I2C, ... with a software controllable ENABLE switch.

User Interface

RoSys plays very well with NiceGUI and provides additional robot-related UI elements. NiceGUI is a high-level web UI framework on top of JustPy. This means you can write all UI code in Python. The state is automatically reflected in the browser through WebSockets. RoSys can also be used with other user interfaces or interaction models if required, for example a completely app-based control through Bluetooth Low Energy with Flutter.


Modules can notify the user through rosys.notify('message to the user'). When using NiceGUI, the notifications will show as snackbar messages. The history of notifications is stored in the list rosys.notifications.