Crafted Matter

Understanding and designing mechanisms has interested mathematicians, artists, and engineers alike. Automaton designers of the 19th century used cam mechanisms to empirically program the motion of a robot’s arm along a specified trajectory. However, it was Alfred Kempe who proposed in 1875 a universal algorithm for mechanism design, often difficult to realise in experiments, to create a linkage assembly that can traverse any trajectory.

In this talk, we will explore the capabilities of a Scissor linkage mechanism made of a series of connected scissor units with a single degree of freedom. The geometry of the mechanism is determined by each unit’s aspect ratio and the deployment angle. We show that the mechanism’s geometry is closely related to discrete curves in 2D and we can thus leverage its representation to program its shape in the deployed state. By tuning the aspect ratio of the mechanism, we control the trajectory of its distal end, demonstrating its ability to 'write'. We build a robotic platform with precision 3D-printed models to test the predictions of our theoretical model in experiments. Our results highlight new avenues for shape-morphing mechanisms using an assembly of simple units, while simultaneously emphasising their limitations.