Swarm robotics focuses on designing and coordinating large groups of relatively simple robots to perform tasks in a decentralised and collective manner. The swarm provides a resilient and flexible solution for many applications. However, contemporary swarm robots have a significant power problem in that secondary (i.e. rechargeable) batteries are slow to charge and offer lifetimes of only a few years, increasing maintenance costs and pollution due to battery replacement. We imagine a different future, wherein battery-free robots powered by supercapacitors can be recharged in seconds, offer long-life autonomous operation and can rapidly pass charge between one another using trophallaxis. In pursuit of this vision, we contribute the CapBot, a battery-free swarm robot equipped with Mecanum wheels, a Cortex M4F application processor and Bluetooth Low Energy networking. The CapBot fully recharges in 16 s, offers 51 min of autonomous operation at top speed, and can transfer up to 50 % of its available charge to a peer via trophallaxis in under 20 s. The CapBot is fully open source and all software and hardware source is available online.

Body area networking is an important segment of the wireless landscape, connecting a growing range of devices such as fitness trackers and smart watches using short range wireless links. However, conventional wireless technologies such as BLE and ANT provide poor support for low-latency applications such as haptic feedback due to their dependence upon duty-cycling to maintain acceptable power consumption. Recent physical-layer design efforts introduce a low-power alternative by establishing capacitively coupled communication through the human body. This mitigates duty-cycling requirements, but results in channel access times similar to those found in more conventional wireless networks, failing to provide adequate latency guarantees even for modestly sized networks. We address this problem by introducing ENOCH, an ultra-low power 12 MHz receiver that relies on capacitive coupling to establish a fieldbus-like through-body network. ENOCH delivers a sub-μW receiver, 10 kbps link-layer throughput, traffic prioritisation, 97% baseline reliability and 7 ms latency in a 7-node network, regardless of contention for the channel. Our design is simple and uses only commercial off-the-shelf components. As it requires neither large antennas nor crystal oscillators, we believe that further miniaturization beyond the current 1 cm2hardware/software prototype is possible.

A growing range of networked embedded devices are moving away from batteries and towards super-capacitor charge storage. However, mobile robots remain largely dependent upon batteries with slow recharge cycles and limited lifetimes. In this demonstration paper, we introduce a novel battery-free platform for swarm robotics which features: 24 minutes of operation running at its top speed of 1.24 km/h, a carrying capacity of over 2.5kg, full recharge cycles of under 12 seconds and rapid peer-to-peer charge transfer or trophallaxis in the field. This is supported by an nRF52840 Cortex-M4F equipped with BLE/ANT/802.15.4 transceiver. Notably, while the autonomy of FreeBots is limited compared to battery-powered robots, their operational vs charging duty-cycle is significantly higher at over 99%.

Intelligent Environments (IEs) enrich the physical world by connecting it to software applications in order to increase user comfort, safety and efficiency. IEs are often supported by wireless networks of smart sensors and actuators, which offer multi-year battery life within small packages. However, existing radio mesh networks suffer from high latency, which precludes their use in many user interface systems such as real-time speech, touch or positioning. While recent advances in optical networks promise low end-to-end latency through symbol-synchronous transmission, current approaches are power hungry and therefore cannot be battery powered. We tackle this problem by introducing BoboLink, a mesh network that delivers low-power and low-latency optical networking through a combination of symbol-synchronous transmission and a novel wake-up technology. BoboLink delivers mesh-wide wake-up in 1.13ms, with a quiescent power consumption of 237µW. This enables building-wide human computer interfaces to be seamlessly delivered using wireless mesh networks for the first time.

The short lifespan of conventional smartphone batteries leads to toxic waste and increases replacement costs. In addition, contemporary devices require reliable electrical infrastructure which remains unavailable in major parts of the developing world. To address these problems, we propose a BAttery-free Mobile Interactive device (BaMbI), which aims to offer a scaled down set of smartphone features. BaMbI is based around an ARM Cortex M33 module with integrated LTE-M. In place of a battery, BaMbI uses a solar panel and an array of super-capacitors that offer sustainable operation and that can be fully charged in under one minute when mains power becomes available.