PCBot: a Minimalist Robot Designed for Swarm Applications

TL;DR

PCBot introduces a minimalist swarm robot built around a PCB-embedded bi-stable solenoid actuator to drastically simplify manufacturing and reduce actuation mass. By toggling attachment to and detachment from an orbital shake table, PCBot achieves controlled motion with only five major components and sub-20 second assembly time, while a polarized-light sensor provides orientation tracking without gyroscopes. The authors detail the electromagnetic and mechanical design, coil-geometry optimization for energy efficiency, and demonstrate straight-line and path-following locomotion alongside a power consumption analysis. This work offers a scalable, mass-manufacturable platform for swarm robotics and lays groundwork for future inter-robot communication and bearing/distance sensing to enable swarm algorithms on a compact, low-cost chassis.

Abstract

Complexity, cost, and power requirements for the actuation of individual robots can play a large factor in limiting the size of robotic swarms. Here we present PCBot, a minimalist robot that can precisely move on an orbital shake table using a bi-stable solenoid actuator built directly into its PCB. This allows the actuator to be built as part of the automated PCB manufacturing process, greatly reducing the impact it has on manual assembly. Thanks to this novel actuator design, PCBot has merely five major components and can be assembled in under 20 seconds, potentially enabling them to be easily mass-manufactured. Here we present the electro-magnetic and mechanical design of PCBot. Additionally, a prototype robot is used to demonstrate its ability to move in a straight line as well as follow given paths.

Figures (13)

• Figure 1: A photo of PCBot, a robot that uses a PCB-based actuator, and is designed for ease of manufacturing. PCBot's size is $48\times42\times14\,\text{mm}$ and weighs $18\,\text{g}$.
• Figure 2: An exploded view of PCBot. PCBot is comprised of merely five major components: a 3D printed chassis, a PCB, a battery, a steel core which is just a screw, and a magnet with rubber on one side. All these components are off-the-shelf or mass-manufacturable and can be assembled in under 20 seconds.
• Figure 3: The setup of the test environment. A polarized light source hangs from the ceiling to provide robots with global orientation sensing. The orbital shake table surface is made of steel and is coated with a layer of HDPE sheet. PCBots operate on the surface of the orbital shake table.
• Figure 4: A simplified cross-section view of the electro-magnetic subsystem of PCBot. This figure shows the difference between the magnet's position in the 'attached' and 'detached' states. In 'attached' state, the magnet sticks to the surface, and in 'detached' state, the magnet sticks to the spacer on the chassis close to the steel core.
• Figure 5: A simplified diagram showing how the robot moves. In the 'attached' state, as shown in the left part of the figure, the magnet sticks to the table and PCBot revolves around the magnet. When PCBot detaches, the magnet no longer touches the table. Driven by inertia, PCBot maintains its momentum, thus follows a straight path and slides on the table, as shown in the bottom part of the figure. After switching back to 'attached' state, friction force quickly brings PCBot to the same speed as the table and keeps them relatively static, as shown in the right part of the figure. In each actuation cycle, PCBot moves relative to the table, as indicated by the orange arrow. This figure is not drawn to scale.