Automatic Prosthetic Arm




Introduction: Automatic Prosthetic Arm

Development and automation of a glove that allows movement of a printed 3D prosthesis . Useful for disabled.

The prosthesis and glove are based on arduino, are usefull for people disabled. The prosthesis is one of the new inventions that the biomedicine has made.

The person who is going to utilize this prosthesis have to use a glove to control it. The glove has five flex sensors, their job is read the values of every finger move. The glove and the prosthesis are conected by two Bluetooth module HC-05.

One of the benefits this project has is that the costs are more accessibles for people who don't have enough money to buy a professional one.

The materials needed to make the prosthesis are:

  1. Glove (1)
  2. Arduino nano (2)
  3. Bluetooth module (2)
  4. Phenolic plate (1)
  5. 3D Printer
  6. Micro servomotors (5)
  7. Roll of string
  8. 9v Battery (1)
  9. 7.4v, 1.5A Li-po Battery
  10. Swicht (2)
  11. (10k or 22k)Ω Resistor (5)
  12. 330Ω Resistor (1)
  13. LED (2)
  14. Jumpers
  15. Screws
  16. Piece of paper
  17. Scissors
  18. Foil
  19. Glue
  20. 6B Pencil
  21. Maskingtape
  22. 500ml of Ferric chloride

  23. One iron

  24. Transfer paper

  25. soft sandpaper

  26. Dremel

  27. Drill of 1/32

Step 1: Flex Sensors

1. Cut five rectangles of paper of 21.5cm x 2 cm.

2. Fold in half the five rectangles.

3. Strongly paint half of each rectangle with 6B pencil.

4. Take the foil and cut ten rectanges of 0.5cm x 10.75 cm.

5. In the other half that is not painted, put aluminum foils on the edges of the paper and paste them, just as shown in the picture

6. Place a wire for each box of aluminum foil and stick them inside.

7. With the maskingtape joining the two halves of paper, just as seen on the image.

8. Then make the conection with an arduino like in the picture, and upload the code "lectura_de_sensores.ino" to the arduino for read the maximum value of each sensor.

NOTE: Each sensor has a different value.


Step 2: Configuring Modules to "Master" and "slave"

In this step you have to configurate the HC-05 modules. One for "Master" and the other one for "Slave", to do this action you have to use an arduino and upload the code called "Serial".

Take one module HC-05 and make the conection as show in the image bellow.

For a complete information please go to the link bellow, to configurate the Bluetooth modules:

Step 3: Making the Glove

Now you have to take the flex sensors and assemble them to the glove.

The first thing you have to do is print all the STL files, in the folder called "Glove".

Then, you have to paste all the pices in the articulations of each finger of the glove just as it is seen in the image.

After that you have to insert the flex sensors in each slot of the pieces.

Print the STL files, in the folder called "Bracelet", already printed, take the 9v battery and insert it in the box of the bracelet. You have to search a kind of belt to use like a watch, just as seen in the picture.

And we have finished the glove.

Step 4: Making PCB

The next step in this projects is to make the circuist boards, to do this you have to use two arduinos nano, a phenolic plate, transfer paper and a masking tape.

The first thing you have to do is print on the transfer paper the PDF files called "Glove" and "Prosthesis".

Already printed, you have to cut two rectangles of the dimentions of the printing, then sand the phenolic plate with the sandpaper in only one direction.

Therefore, take the printing of the "glove" cut it, and join to the phenolic plate. On the banks of the phenolic plate placed pieces of tape.

Then, using the iron, ironing phenolic plate tha have the transfer paper for 15 minuts. After that, fill a container with a little water and put the gangplank plate in it. Leave wetting the plate for 7 minutes.

Now you have to remove the paper and tape to the plate, and finally pour 300ml of ferric chloride in a container and 300ml water in the same container.

And then put the plate in the container and let stand for 20 minutes until you go removing copper.

Finally you have to wash it and perforate with the drill of 1/32 and solder all the components.

NOTE: You have to do the same process to make the other circuit.

The circuit of the glove you have to pasted to the printed file "Palm_mirrored" just as seen in the picture. Conect the power source to the circuit and the flex sensors too.

Finally upload the code called "Actions.ino".

And in the other circuit upload the code called "Servo_s_control.ino".

Step 5: Prosthesis

  1. Print all the STL files of the folder called "Prosthesis"
  2. Assemble all the pieces
  3. Using the string, make all the conections of each finger. One end of the string has to raise the finger and the other end has to lower it when you pull.
  4. Take the files printed called "Servomotors left" and "Servomotors right", paste them and tying one end of the string to one end of the servo arm and the other end of the cord to the other arm.
  5. Finally screw the arm plate to STL file called base paste inside.
  6. Conect all the servomotors to each concection of the circuit

Step 6: Make the Bluetooth Conection

To sump up this project you have to turn on both circuits and the bluetooth modules will make the conection, after that, make the corresponding movements to trigger commands to activate the prothesis.

And tha's all. We have finished :)

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    2 Discussions

    DIY Hacks and How Tos

    Nice. I have always thought the there is a great need for DIY prosthetic that can be personalized to the user.