Projects

Wearable Mult-Sensor Glove for Soft Robotic Actuator

Multilayer Direct Ink writing

This project started as a collaboration between Voltera(the manufacturers of the Nova) and during a beta testing period of a new feature for their system.

I proposed to develop a textile glove that contained both a strain gauge and pressure sensor fabricated at the same time using their new Plan feature.

3D COMSOL simulation of strain gauge element to determine optimal steady state capacitance for the accompanying capacitance-to-digital converter (CDC).

Strain Gauge Modelling

In order to accurately detect the soft robots joint angle a strain gauge that was capable of detecting a wide range of strain with minimal hysteresis was required. A 2D model shown in the GIF beside was utilized to tune the number of electrodes and geometry of the sensor to match the CDC and robot gripper requirements

Prototype

A basic single layer prototype was designed and fabricated using the new beta features which provided greater control of tool pathing and deposition characteristics. After the steady state capacitance was validated against the COMSOL model the next step in the design phase could take place.

Preliminary Design

The first design was based on limiting the direct ink writing (DIW) to only three layers and a final post processing fold and bond step. This was ultimately not used due to durability concerns of the connection from the pressure sensor plate being folder. A four layer process was developed.

Pressure sensor validation

As the soft robotic gripper was inherently compliant the pressure sensor array elements would need to detect small pressure applied to the surface. A basic dielectric structure was found to suit the needs required for robotic grippers control logic and was crucial in improving the pressure cell yields.

Integration

With both individual elements validated the combination of the two was tested as a single fabrication file. A compromise between ultimate resolution and speed was found to ensure that the strain gauge was produced accurately with continuous coverage on the pressure sensor.

Final Fabrication

Monolithic Soft Robotic Gripper Design Case Study

Original actuator with designed support structures

Why soft robotic grippers

Soft robotics enables safe, adaptive interaction with complex and fragile objects—capabilities that traditional rigid systems often lack. By leveraging compliant materials and bio-inspired designs, soft robotic grippers can conform to diverse shapes without precise positioning or force control. This approach expands the potential for automation in sensitive, dynamic environments such as medical handling, agriculture, and advanced manufacturing. This project was done for the development of a new undergraduate lab as well as a component to the final project of ME 739.

Preliminary Study

The goal of this project was to create a robust toolset to generate internal supporting structures that enhance the manufacturability of soft robotic devices.

The first stage of the project was to get a baseline performance for various geometries of soft robotic actuators. These were all designed with minimal manufacturing constraints applied as this would be addressed with the engineered lattice infill. After the larger parametric sweep was aggregated an initially optimized gripper was chosen.

Homogenization Simulation

FEA simulations were conducted within nTopology on common lattice structures that were selected to be feasible in a Silicone SLA process. Since each lattice is modelled with thousands of mesh elements it is difficult to simulate a fully meshed part. Each single lattice is stressed from multiple directions to build a bulk material tensor which can be used in a simplified model to save computational time.

Bulk Simulation

With each lattice represented as a linear elastic material a secondary FEA study within nTopology was performed looking at the deformation of the finger element with various loads and lattice infill types.

These lattices were then optimized to bias their performance along their supporting axis to improve performance and manufacturability of the grippers.

Final comparison

A final analysis concluded that there was an optimal generative lattice infill that achieved similar gripping displacement as the completely hollow gripper but could be 3D printed at once on a Formlabs SLA printer.

3D printed sample

Simplified Simulation Framework for the development of Soft Pneumatic Actuators – Multi-layered Bellows

Educational Toolset

In an effort to promote soft robotics and improve accessibility a standalone COMSOL simulation application was created allowing researchers and students to quickly optimize basic bellows style soft robotic actuators.

This model was optimized by assuming perfect bonding seems and a revolved 2D approximation, leading to a extremely fast and relatively accurate model.

Outputs

Once the user inputs their desired geometry, operating pressures, and many more optional parameters the simulation software can generate a visualization as well as output the predicted performance, helping them size actuators for their pneumatic supply and application.

Failure Analysis

An additional feature that was implemented into the model is the failure predictor. If the user inputs sufficient material properties the model can predict at which pressure the material is expected to yield. This was however, not capable of detecting delamination failures that are more commonly observed in real world bellows.

Final Results

Ping-Pong Practice Bot

Designed and prototyped an Arduino controlled Ping-Pong Practice Robot to consistently shoot ping-pong balls at various angles.
Custom components were designed in SolidWorks and 3D printed in PLA using an Ender 3 printer.
Robot was programmed in Arduino and utilized 3 motors to regulate ball speed and launch bearing angle.

First version using a catapult like system and a worm drive.

Two high speed rotating flywheels with a rail to redirect the ping pong ball.

Switch to "Jugs" style launching

After it was found that the initial design was not suitable for the low torque DC motors that were on-hand we tried using different high ratio gear sets. However, the friction between the two 3D printed plastic parts proved to be too great to be an effective solution.
To take advantage of the high speed motors we changed focus to a launching system similar of that to a baseball pitching machine which has two high speed rotating wheels which pull and launch the ping pong ball out.

Next steps

We are currently working on the system integration of an Arduino micro-controller with several sensing breakout boards and a HC-05 Bluetooth module to allow the robot to be controlled by a custom built Android app.
Concurrently, to enable yaw rotation control; development of a rotating platform powered by a servo motor is being worked on. Combining this with a laser ping sensor which can determine the distance of an object in front of the robot, we can get the robot to detect and adjust its launch parameters to accurately hit the cup with the ball.

System Integration

After successfully creating a motor driving circuit with two TIP31A Mosfets as well as implementing a photo-resistor voltage divider circuit used in conjunction with black electrical tape to form a crude tachometer all that was left to do was code.
Using a Java based Android development framework a simple app to control the robot from a mobile device as well as relay distance to cups and rpm of the flywheels.
In the video to the right the main sequence was enabled on the phone which measures the distance to the cup directly in front of the robot and turns the motors on until the reach a set rpm found in a simple look up table where the motors then perform a speed maintenance mode as PID control was found to not be suitable with the noise found in the Photo resistors.

video-1617570303.mp4

Stock Viewer App

Object Orientated Python executable which can store and display portfolio data including built in stock researcher.

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