Stanford Seminar - Engineering physical principles of embryonic morphogenesis in robotic collectives

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Morphogenesis in Robots

Morphogenesis is the process by which an embryo changes shape by rearranging its cells.
Current collective robots can change shape but are limited to perimeter motions.
The goal is to create a robot that can rearrange its cells in a tight-packed situation throughout the material.
The basic way to rearrange the topology of cells is called the T1 transition or intercalation.

The final design of the robots included a custom circuit board, cheap motors, batteries, gears, and sensors.
To create surface flows, the team used gears driven by motors along the surface of the robot.
For adhesion, magnets were embedded in the robots and allowed to rotate to match the orientation of neighboring robots.
To polarize the robots, polarized light was used. Each robot had photodiodes with polarized film on top, and a second polarized film was placed above the arena.

The robots were able to successfully perform T1 transitions when the polarized light was shone on them.
The researchers conducted experiments to understand how the shape and strength of a collective of robots change in response to different parameters.
They observed a sharp threshold in the force required for motion, both when varying the average force and the amplitude of fluctuations.
The researchers found that as the amplitude of fluctuations increases, the average force required for motion decreases.
A steep bimodal distribution of force pulses is most effective for shape change.

The robots can be turned on and off, and their stiffness and strength can be controlled by varying the inter-unit force and vibrations.
The power consumption of the robots is reduced when they are fluctuating, but the energy required is similar.
The robots can be controlled collectively, and they can rearrange themselves and change shape in response to light stimuli.
The collective of robots can be turned into a viscoelastic material that can be deformed and reshaped.
The robots can exhibit spatial control, where one side of the collective can be fluctuating while the other side is not.