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Soft Manipulator

About

The Sorotoki toolkit provides a soft robotic manipulator that features three independent bellow networks and a three-fingered soft robotic gripper attached to the end effector (see above). With independent actuation of each bellow network, the manipulator has a full 3D workspace of approximately 150 \(\times\) 150 \(\times\) 150 mm. The soft elements of the manipulator are fabricated using Elastic 80A resin, while the rigid connector pieces are made using Rigid 10K resin. The gripper has demonstrated the ability to successfully grip objects with a diameter of 40mm, with a maximum payload of 100g without significant parasitic deformation. The central axis of the manipulator is designed to be hollow, enabling the pneumatic tubing of the gripper and the cables for state estimation sensors (e.g. IMUs) to be embedded. The manipulator has three inputs that accepts \(-10 \le u \le 30\) kPa, and the gripper has one input port that accepts \(-30 \le u \le 60\) kPa.

Fabrication details

The soft manipulator is fully printable. Below, we provided a list of the printer materials.

  • 1\(\times\): Soft Bellow - Elastic 80A - Formlabs (recommended)
  • 3\(\times\): Soft Finger - Elastic 80A - Formlabs (recommended)
  • 1\(\times\): Connector One-way - Rigid 10k - Formlabs (optional)
  • 1\(\times\): Connector Three-way - Rigid 10k - Formlabs (optional)
  • 1\(\times\): Base mount M6 - Prusament PLA Azure - Prusa (optional)
Printing of Elastic 80A

When printing Elastic 80A, the recommended supports for the material are very thick -- thus difficult to remove. We recommend generating the supports using Rigid 10K, then change the material to Elastic 80A. Support can then be easily removed manually (no pliers required).

Cleaning and closing of Soft Actuators

A crucial step is cleaning of the elastic resin parts. If residual resin is not properly removed/cleaned, it will greatly affect the quality and performance of the soft actuator. We recommend following the cleaning procedures proposed in Proper et al. 1, see Git documentation. The paper draft can be found here: Paper.pdf. In their approach, a perastaltic pump is used to pump cleaning fluid through the soft actuator prior to curing. To allow fluid to flow, both sides of the soft actuator are open! They must be closed using 3 mm plug printed from the same material! The plug can be glued in place using uncured resin, and then placed in an UV chamber for a short duration.

Connecting Soft Actuator to Rigid Connector

Similar to closing of the soft actuators, uncured resin can be used to make a robust connection to the rigid pressure connector. This greatly improves air-tightness of the complete system.

Downloadable content

Complete Soft Robot Manipulator - 14.6 MB uncompressed (.zip)

Soft Bellow (STL) Soft Finger (STL) Connector One-way (STL)

Connector Three-way (STL) Base mount M6 (STL)

3D Visualization

  1. Proper. B, Caasenbrood, B., & I. Kuling (2023). Easy Cleaning of 3D SLA/DLP Printed Soft Fluidic Actuators with Complex Internal Geometry. 6th IEEE International Conference on Soft Robotics, RoboSoft 2023. (submitted). https://github.com/ReshapeTUe/Peristaltic-Pump-Documentation ↩