Section: New Results

Information-centric IoT Robotics

Participants : Loic Dauphin, Cedric Adjih, Emmanuel Baccelli.

As IoT emerges, minibots (miniature robots) have appeared on the market. A large community emerged, designing do-it- yourself minibots, and cheap, re-programmable minibots with communication capabilities are now available. For in- stance, small wheeled robots such as the Zooid are based on a small microcontroller (8kB RAM, 64kB ROM) and communicating with a low-power radio in the 2.4 GHz ISM band. Other examples are cheap drones such as the Cheerson CX-10, which has similar hardware characteristics, and which costs under 15$. Simple robotic arms and legged robots are also available, such as the MetaBot. A current trend bases software embedded in minibots on open source frameworks. The Robot Operating System (ROS) is a software framework for robot application development which has become a de facto standard for most areas in robotics. Other open source robotics frameworks include software suite tailored for drones, some of which provide compatibility with ROS. In fact, we observe that minibots have a number of charac- teristics in common with low-end devices found in the Internet of Things (IoT). Compared to low-end IoT devices, minibots are based on similar hardware and their software follows similar trends. For instance, an IoT-enabled actuator based on a System-on-Chip (SoC) embarking a small microcontroller, and a radio communicating with a remote server, is very similar to a simple radio-controlled robot. Low-end IoT devices use similar radio modules, and software embedded in IoT devices is more and more based on a variety of open source, lightweight operating systems such as RIOT, FreeRTOS and NuttX, among others. Similarly, as for IoT embedded systems, the network com- ponent of minibots represents by itself in important part of the software (in terms of features, code/memory size, and performance). In fact, a wide variety of radio modules and communication protocols are used on minibots. The protocols used by micro-robots for (internal or external) communication range from direct motor control (pulse width modulation PWM, pulse position modulation PPM, or PCM), to serial/bus protocols, and high level protocols such as Real-time Publish- Subscribe Protocol (RTPS). In this work we thus to explored the potential of bundling open source robotics software frameworks with IoT software and network architectures, to program and control minibots. To do so, we extend our recent work by designing ROS-ready technology for a minibot based on RIOT and ROS2. We focus primarily on software and networking aspects, targeting ultra-lightweight robots based on a reprogrammable SoC with a microcontroller running at approximately 50 MHz, with 10kB RAM, 100kB Flash, and a low-power radio. Using an information-centric networking paradigm extending NDN, we design and implement the communication primitives required by RIOT-ROS2. Our prototype is able to maintain full compatibility between ROS nodes running on the minibot(s) and ROS nodes running elsewhere on the network without the use of a bridge. We show that RIOT-ROS2 fits on low-end robotics hardware such as a System-on-Chip with an ARM Cortex-M0+ microcontroller. On the software and network performance evaluation side, we illustrate that the latency incurred with our ICN approach is completely acceptable for minibot control, even on constrained radio, based on micro-benchmarks.

This work was published and presented at the IEEE PEMWN 2018 conference as ”RIOT-ROS2: Low-Cost Robots in IoT Controlled via Information-Centric Networking”.