this repository shows the development of the upper limb arm. The general structure of this prosthetic arm treated as continuous improvement of the existing prosthetic arm. After a complete inspection of the essential elements and analysis of the available components.
This project consist of 5 important pillars which is a must for the project to be feasable possible to make.
- CAD (Computer Aided Design) software for designing the hand as it was designed all from scratch to meet consumer demands
- CAM (Computer Aided Manufaturing) which involves of manufacturing the product using a 3D printer and polyflex filament
- FEA (Finite Element Analysis) this part involves the simulation of forces applied to the hand determining its mechanical properties
- The use of flexible filament contributing as a part of soft mechanisms and materials resulting in flexible hand design which results in better grip of objects
- Performing multiple strengh test such as compression and tesile test
This repository will show how to print the hand parts, assemble them and will showing some videos in simulationshowing how the hand function.
3D Printer
Polyflex (flexible) filament
3 Servo motors
3 Strings
Arduino uno
Use the flexible polyflex-tpu95 filament which could be found here https://polymaker.com/product/polyflex-tpu95/
This section is crusial for successfully printing 3D flexible hand using a 3D printer which is apart of CAM process.
- Loosen your idler before you start loading the filament
- Spread a thin layer of glue on your print surface so the printed object could be easily released when done
- print very slowly, safe speed is 20mm/s
- Filament should be dry as flexible filaments absorbs moisture
- Set less dense infill depending on how soft you would like your hand to be the less infill the softer the hand will be
For further and detailed instructions about printing flexible materials open this link
https://blog.prusaprinters.org/how-to-print-with-flexible-filament_29672/
Our robot hand's idea is to have flexibility and design each branch to separate and assemble.It has a wave structure for added grip and flexibility. The design was all done from scratch using CAD fusion 360 software.
Thumb design play a very important role in grabbing objects with other fingers and structures. so it has a special design.
Our robot also chose this design to absorb the impact by increasing the flexibility of the part where the object touches thinner part to give it more flexibility.
This section we will show the assembly of the hand using pictures its main concept relies on the joint to assemble parts together showing how to lock the joints together.
The lock in the figure below is inserted between the slots of the other joint.
Every joint is inserted the same way and the process is repeated for the same parts onto the other joints until the rest of the hand is fully assembled.
In this the designed hand is went through testing and simulation to determine the hand usability and specifications.
The filament used for printing is PolyFlex (TPU95) which has specific mechanical properties which are fed into the simulation program determining and estimating the hand properties and usability. This is the part of FEA and tensile strengh testing of elastic materials which might be applied in application where soft robotics are needed.
the first test performed was the finger bending between the joints
Material properties is set in simulation parameters
A simulation is set to determine how mch of force needed to be applied so the finger won't deform permanently on it wave structure to determine how much compresikon force can a joint hold.
The hand is animated to represent different gestures which the hand is capable of due to its extended degree of freedom
The final goal of our design was to catch soft objects and to make it easier to assemble and disassemble fingers, so that the robot hand users could easily replace them when their hands when broken. Future and potential work will focus mainly on more fingure to mimic exactly the human hand and again more degree of freedom including the palm.