MROS provides the core functionality of the MR01 Mars Rover, a Raspberry Pi-based robot OS written in Python 3.
A 3D model of the MR01 Robot.
The MROS library provides essential support designed as the basis of a Behaviour-Based Systems (BBS). This library is relatively "low-level" and, in theory, could be used for any Python 3 based robot.
The basic function is for sensors to act as "Publishers" in a "Publish-Subscribe" model, firing event-laden messages onto an asynchronous message bus. Subscribers to the bus can filter which event types they are interested in. The flow of messages are thus filtered through the Subscribers, who pass on to an Arbitrator messages they have consumed. Once all Subscribers have acknowledged a message it is passed to a Garbage Collector (a specialised Subscriber).
Each event type has a fixed priority. The Arbitrator receives this flow of events and passes along to a Controller the highest priority event for a given clock cycle (typically 50ms/20Hz). The Controller takes the highest priority event and for that clock cycle initiates any Behaviours registered for that event type.
For example, a Subscriber that filters on bumper events receives a message whose event type is Event.BUMPER_PORT (the left/port side bumper has been triggered). This Subscriber passes the Payload of its Message to the Arbitrator. Since a bumper press is a relatively high priority event it's likely that it will be the highest priority and is therefore passed on to the Controller. If an avoidance Behaviour — let's call it AVOID_PORT — has been registered with the Controller, it is called and the robot will begin whatever the AvoidPort behaviour entails, perhaps stopping, backing up while turning clockwise, then proceeding forward again on a new trajectory.
- message and event handling
- an asynchronous message bus that forms the basis of a Subsumption Architecture [1], with an "exactly-once' message delivery guarantee
- YAML-based configuration
- timestamped, multi-level, colorised [2] logging
- written in Python 3
| [1] | Uses finite state machines, an asynchronous message bus, an arbitrator and controller for task prioritisation. |
| [2] | Colorised console output tested only on Unix/Linux operating systems. |
This library requires Python 3.8.5 or newer. Some portions (modules) of the KROS code will only run on a Raspberry Pi, though KROS Core should function independently of the various Pi libraries.
KROS requires installation of a number of dependencies (support libraries), which should be automatically installed via pip3 when you installed kros-core:
Early days. The Phase 0 hardware is largely complete and migration and conversion of the KROS-Core is being used as the basis of MROS.
Note
This project is currently in a very preliminary state.
The project is being exposed publicly so that those interested can follow its progress.
This project comes with no promise of support or acceptance of liability. Use at your own risk.
All contents (including software, documentation and images) Copyright 2020-2024 by Murray Altheim. All rights reserved.
Software and documentation are distributed under the MIT License, see LICENSE file included with project.