A paper based on this research was published: Color-Based Sensing of Bending Deformation on Soft Robots

Design Challenge

Measure the deformation in a soft actuator using multi-material 3D printer.

Soft Robots exist in different shapes and forms. Compaired to traditional robots, soft robots are created out of soft materials and controlled by air pressure. This enables soft robots to grab soft objects (e.g. tomatoes) without damaging them. The drawback of soft actuators are the infinate joints, which make it almost impossible to control their position in great detail.

At the Delft University of Technology we can 3D print soft actuators using the Connex PolyJet Multi-Material 3D printer. This machine can print materials of different hardnesses but also with different color grades. I worked in a team of two to design a sensor to measure the deformation in a 3D printed soft actuator using color. In this way we would be able to print a actuator and sensor in one go, eliminating the need for assembly.

This project focuses on using color and a color sensor to measure the deformation of the actuator. Air enters through a valve into the soft actuator causing the actuator to bend. By measuring the deformation, a controller can control the valve and thus the deformation.

Improved Soft Actuator

During the project I worked on an improved design of the soft actuator. We introduced several improvements to increase the reliability of the actuator.

Improved design of the Soft Actuator. During the project we added different layers on the bottom to prevent cracking, stiffer bows to keep the bellows from expanding outwards and an improved endplug design facilitate removal of support material.

Colored structure

During the project I focused on the design of the colored structure. By creating a clever structure which exposes a specific color when the actuator bends, while exposing another colour when the actuator is in the neutral position.

Differnent color structures were prototyped and tested.
Final video – Color-Based Sensing of Color-based Sensing of Bending Deformation on Soft Robots