Hello, this is Long Grey Engineering and today we are presenting to you the building operations for project Graspit. Project Graspit is a 3D printed Robotic Hand controlled by a separate glove. If you follow these steps you too can create your own hand. This Project is a continuation and add on of a project done by the user dschurman.
Step 1: Materials Needed
1x Arduino 101 board
1x Mechanic Glove
1x Spool of Goture 10-LB (124 Yds) Superpower Braided Fishing Line–Zero Stretch and High Tension Advanced Multifilament line
1x Printer or Access to 3D Printer
1x Spool of ABS Plastic
3x 9v Battery
3x 9v Snap Connectors
5x 4.5 inch Flex Sensor
5x Tower Pro MG996R Servo Motor
32x Male-Male Jumper Wires
10x Female-Male Jumper Wires
15x Flat Breadboard Wires
- 5 White Wires
- 5 Blue Wires
- 5 Orange Wires
Step 2: 3D Print the Hand
In order to print the hand you will need to use a 3D printer that is capable of printing ABS Plastic.
The file for the hand is attached for your use.
Step 3: Asemble the Parts of the Hand Together
The next step is to attach the fingers and base to the palm. Make sure to check each part and clear any support material left behind inside or around. We used a flat head screwdriver and a small pry bar to remove the support material left inside the grooves and cavities of the parts.
Be careful to pay attention on the orientation of each finger segment because the movement of the hand and tendons depend on it. Before attaching anything together, lay out each section of each finger and label them so you do not get confused when assembling. Our printed parts needed a fair amount of additional sanding around the joints in order to for the finger to move more smoothly.
The next step was to run the fishing line through each finger and down through the palm. We recommend leaving about 2 feet of slack on each finger for adjustments when hooking up to the servo motors. We also used masking tape to label the strings relative to each finger.
The next step was to superglue the pieces of each finger together and then add temporary pins to the joints to hold the hand together. When the hand is secured together, the next step was to use a soddering gun to melt each piece togehter where the glue was a pplied.
For the pins on the fingers, we used small common wire nails and cut them down to size using a wire cutter. Each joint pin is a slightly different size depending on each section so it helps to mark them also. For the big pins on the palm and wrist, we recommend stainless bolts, but the 3-D printed pins that are in the file can also be used if sanded down. For the finger pins, the side clipped off by the wire cutters slips out easily, so we recommend adding a dab of hot glue on the side to keep it from sliding out.
Step 4: Sew the Flex Sensors to the Glove
Step 1: In this step you will want to sew the flex sensors to the fingers on the glove. After you sew the sensors on the glove you will then want to attach the jumper wires to the board. The wires that are on the glove are color coordinated to the wires on the board. Attached is the picture of the completed glove.
Step 5: Develop the Code
While you or your team is assembling the hand you can finalize the code and adjust the code in order to meet the specific ports that are on the board.
Below is the Code that was used. This Code is open source.
Step 6: Assemble the Arduino Board and Breadboard
Step 1: The first step in assembling the Arduino board is to set up the five flex sensors onto the Circuit Board. The schematic for each flex sensor is in the first picture. The circuit board with all five flex sensors is also shown in the second picture. In the second photo each flex sensor will have a male/female jumper wire in which the actual flex sensor is attached to the board.
Step 2: The next step in assembling the board is to connect each flex sensor to their respective analog in pins. The jumper wires for these connections can be seen in the second and third picture and are the red, yellow, red, white, and white colored wires. These wires will read the bend of the flex sensor and will send that feedback to the servo motors.
Step 3: The third step is to set up the five ground and power jumper wires that will attach to the servo motor.
Step 7: Attach Motor Bank to Hand
In this step you will be attaching the hand and all the tendons to servo motor bank.
Step 1: The first step in the final assembly is to attach the forearm to the hand. Once that step is complete you will want to attach the motor bank to the forearm by soldering or supergluing the base of the motor bank to the inside of the forearm.
Step 2: The next step will include running fishing line from each finger to their respective motor (on each spindle is the abbreviation of the finger that it is for). The way that you will want to attach the line to the spindle is that you will want to take the line responsible for closing the finger and will spool it around the spindle and bring it through the hole on the left hand side of the spindle(The motor will spin in a counter-clockwise rotation). This step is repeated for the line responsible for opening the finger, however it will be brought through the hole on the right hand side.
Step 3: After step 2 you will want to make sure the lines are tight and then you will want to superglue or solder the line to the spindle and to the hole to prevent any slipping and unspooling.
Step 4: The next step is to repeat step 2 and step 3 for each of the fingers.