High-Density Tactile Sensing Artificial Fingertip for Humanoids and Prosthetics
This project focuses on the design and development of a high-density tactile fingertip module intended for humanoid robot and prosthetic hand applications. The module is capable of measuring pressure exerted on its surface through 22 individual pressure sensors distributed across the fingertip area. It is developed using Flexible Printed Circuit Board (Flex-PCB) technology.
In this project, an origami technique is employed to fold a flat, paper-like flexible tactile sensing module into a three-dimensional shape that mimics the form of a human fingertip. Sensor data acquisition is handled by an onboard 32-bit, low-power microcontroller, and the module communicates using the SPI protocol.
In this project, an origami technique is employed to fold a flat, paper-like flexible tactile sensing module into a three-dimensional shape that mimics the form of a human fingertip. Sensor data acquisition is handled by an onboard 32-bit, low-power microcontroller, and the module communicates using the SPI protocol.
In this project, an origami technique is employed to fold a flat, paper-like flexible tactile sensing module into a three-dimensional shape that mimics the form of a human fingertip. Sensor data acquisition is handled by an onboard 32-bit, low-power microcontroller, and the module communicates using the SPI protocol.
The development of this module presented a number of challenges, particularly in mechanical design and electronics. Prior to this project, I had limited experience with mechanical Computer-Aided Design (CAD). I had to learn how to design both mechanical structures and electronic schematics, as well as manage the manufacturing and integration processes.
Despite these challenges, a functional prototype of the tactile fingertip was developed. While the current version is not yet optimized for production, it is capable of capturing tactile data. Ongoing work includes further optimization of the design, data collection, and analysis.
The dimensions of the fingertip module closely match those of a typical human fingertip, enabling applications in humanoid robots and prosthetic systems.
CAD Model
Figure 2:
The CAD model on the left illustrates the structural design and assembly of the high-density tactile fingertip module. It was created using Siemens Solid Edge, leveraging the sheet metal environment to model the foldable geometry of the flexible PCB. The part environment was used to design and integrate additional components, including pressure sensors and the onboard microcontroller.
Board Layout
The schematics and board layout of the tactile fingertip module were designed using Autodesk Eagle EDA. It was a challenging task, as a large number of vias had to be managed within a very small area. The board layout includes approximately 218 vias on a two-layer flexible PCB, with dimensions around 32 mm × 74 mm.
Figure 3: Board layout of the tactile fingertip module.
Fully Populated Tactile Fingertip Module
The tactile fingertip module is manufactured using 2-layer flexible PCB technology with a thickness of 0.11 mm. After fabrication, surface-mount technology (SMT) is used to populate the electronic components.
Figure 4 depicts the fully populated tactile fingertip flexible PCB placed next to a 10-cent coin, highlighting the size difference and the complexity of the design.
Figure 4: Fully fabricated and populated tactile fingertip module in flat form factor.
Origami
A technique called origami, a traditional Japanese art of folding paper to form intricate shapes, is applied here to transform the flat version of the flexible tactile fingertip module into a 3D shape resembling a fingertip. Although origami is a complex art and I don't have much expertise in it, I attempted a simplified version to apply the technique as best as I could. The figure below shows the fingertip after being folded using origami techniques, including both the top (Figure 5a) and bottom (Figure 5b) views. The bottom view represents the fleshy part of the fingertip.
Figure 5: Top (a) and Bottom (b) views of the tactile fingertip module folded into a 3D humanoid fingertip-like shape using origami techniques.
Tactile Fingertip on a Human Finger
Figure 6: Shows the high-density tactile fingertip module mounted on a human finger. This demonstration is for illustrative purposes only. While the module is designed for integration into a humanoid robot hand, I did not have access to the robot hand toward the end of the project. I plan to update this demonstration with a robotic hand implementation in the near future.
Future Work
Further work on data collection, analysis, and system optimization is planned. In future updates, I aim to include additional documentation such as:
- Detailed experimental results
- Data analysis and sensor performance evaluations
This project will likely continue to evolve as time allows. At the moment, my availability is limited due to involvement in other work. While I have clear plans for improvements, progress will depend on available time."
I haven't published the data, schematics, or full documentation yet, as I believe the project isn’t complete enough to share publicly. Once it reaches a point I consider satisfactory, I will make those materials available.
I haven't published the data, schematics, or full documentation yet, as I believe the project isn’t complete enough to share publicly. Once it reaches a point I consider satisfactory, I will make those materials available.