Sensory Feedback - Raptor Reloaded

Hi everyone,

This is a project done by me and my partner Moran, the project was done under the supervision of Yoav Medan, in the Bio-medical engineering department at the Technion and in conjunction with Haifa3D.

The goal of the project was to add the sense of touch to a 3D printed Raptor Reloaded, this was achieved using 3 type of sensors: pressure, location and temperature (the temperature sensor is mainly used to protect the hand from excessive heat). The feedback to the user is passed using a feedback band which is based on 2 servo motors and a vibration motor. The entire design is based on simple off the shelf parts and the cost is ~60$ in addition to the regular cost of the Raptor Reloaded.

The mechanical model is based on e-NABLEs Raptor Reloaded and the Carmel thumb.

In addition to the design itself an emulator was developed in order to test the design, the emulator can be useful for developers working on improving the Raptor Reloaded.

In order to build the hand you will need basic knowledge in electronics, Arduino and 3D printing.

Tools Required:

· 3D printer.

· Soldering iron & solder.

· Hot glue gun.

· Caulk gun.

· Wire wrap tool (Optional).

· Box cutter.

· Wire stripper.

· Measuring tape.

· Machine oil.

· Screw driver.

· Heat gun\ Hear dryer.

· Wire cutters.

list of materials needed is attached as a PDF file.

Step 1: Scale and Print All Parts

Parts and Tools Used In This Step:

· 3D Printer.

· Measuring tape.

· Box cutter.

· Printing material AK1.

Scaling (taken from: Raptor reloaded instructable page)

Linear Scaling (easy)

The main measurement used in sizing the Raptor Reloaded is the width of the recipient's complete hand at the knuckles. At 100% scale, the palm of the Raptor Reloaded measures 55mm at its widest point. To get the appropriate linear scaling factor for scaling the STLs, add 5mm (to account for the thickness of padding in the printed palm) to the width of the recipient's complete hand at its widest point. Divide this number by 55 to get the scaling factor for the STLs. For example, if the palm is 65mm wide, then 65 + 5 = 70, and 70 / 55 = 1.27, so the scaling multiplier would be 1.27 or 127%. Make sure to apply the scaling factor to all of the parts to ensure that they fit together. At higher scales, the clearances between the moving parts of the hand will grow, so glue or other modifications may be necessary to ensure that all the pieces stay secured to each other.

Parametric (more involved):

Because radial and lateral clearances for motion assemblies are absolute, linear scaling can cause problems at large scales. For those with some CAD experience, STEP and IGES files are available.

Recommended Printing Settings:

· PLA (or ABS, PET, Nylon for non-thermoformable parts).

· 0.2mm layers.

· 2 shells.

· 35% infill.

· Active cooling fan on.

A list of parts to print is attached as a PDF file.

Step 2: Build the Electronic Circuit

Parts and Tools Used In This Step:

· Soldering iron & solder.

· Wire wrap tool (Optional).

· Box cutter.

· Wire stripper.

· Parts A1-U1.

· Wire cutters.

Instructions

1. Cut the Prototyping board to size according to the attached picture.

Dimensions are in mm, if the hand is scaled, the board can be scaled accordingly.

2. Build the circuit according to the attached schematic

Use the header rows to allow for easy replacement of the Arduino board, connect the terminals to allow for easy replacement of the sensors and motors.

Leave enough slack when connecting the switches for easy removal of the cover (see step 6).

3. Connect wires to the sensors, make sure you leave enough wire for the entire path it needs to go through. There are a few options of how to connect the wires:

a. Use a wire wrap tool and wrap a wire around the pins, do it very carefully since the sensors can be torn easily.

b. Wrap the wire by hand around the pin, since you are not using the appropriate tool, make sure the wrapping is tight enough.

c. Use a crimp connector to connect the wire to the pin, again, do this very carefully to prevent damage to the sensor.

d. Use a soldering iron, this should only be done by someone with experience in delicate soldering because heat can damage the sensors easily.

Any other method would work as long as you are careful since the sensors are very delicate.

Step 3: Embed the Sensors in the Fingertips

Parts and Tools Used In This Step:

· Hot glue gun.

· Caulk gun.

· Machine oil.

· 10 finger molds & 5 finger tips.

· Parts A1, V1-W1.

Instructions

1. Thread the electrical wire through the fingertip as shown in the following image (in the following section the fingertip shown is cut in half for demonstration purposes):

2. Use hot glue (or any other type of glue) to attach the FSR to the bump in the fingertip, make sure the sensor is glued properly.

3. Apply oil on both sides of the mold, on all surfaces.

4. Apply the Caulk in both sides of the mold.

5. Put the fingertip into one side of the mold and close the other on it.

6. Allow to dry for ~24hrs (check the specific caulk you used for exact drying time).

7. Remove molds, make sure all surfaces are smooth, if you see holes, apply some caulk and fill it. Clean finger surfaces from unneeded caulk, use a box cutter to remove bumps in the caulk.

Step 4: Assemble the Feedback Band

Parts and Tools Used In This Step:

· Heat gun\ hear dryer.

· All printed parts related to the feedback band.

· Parts B1, X1-Z1

Instructions:

1. Thread the electronic wires of one servo through the tunnel (marked in blue).

2. Screw in the two servos using the two 2.5X12mm screws.

3. Insert the Push handle and the moving part into place.

4. Insert the gear and crank into place and secure it using the servos included screws.

5. Gather all electronic wires of the feedback band into one heat shrink about 50mm long.

IMPORTANT: In case different servo motors are used make sure that the pressure created by the band is reasonable and cannot cause injury.

Step 5: Assemble the Hand

Instructions:

1. Thread the electric wires through all appropriate tunnels (marked in blue) leave enough slack for the movement of the fingers (exit point marked with orange arrow)

2. Embed the temperature sensor in place (marked in blue) and thread its wires through the tunnel

3. Thread the SoftPot wires through the Hole (marked in blue)

4. Use Hot glue and Velcro to attach the SoftPot to the palm:

5. Thermoform the 3 braces according the shape of the hand. This is done by done by dipping the parts in hot water (nearly boiling) and placing on recipient hand, make sure the part is not too hot.

6. Use Hot glue and Velcro to attach the SoftPot to the palm brace.

7. Attach the upper brace to the palm using the brace pin (marked in blue).

8. Attach the Thumb extension to the palm using a thumb pin (marked in blue).

9. Attach the palm and the gauntlet using the two wrist pins and caps (marked in blue).

10. Attach all the distal parts of the fingers to the appropriate proximal parts using the five finger pins (marked in blue).

11. Attach the four fingers to the palm using the two knuckle pins (marked in blue).

12. Attach the thumb to the thumb extension using a thumb pin (marked in blue).

13. Cut four pieces of 1.75 PLA filament 4mm long and glue them in place.

14. Tie a piece of non-elastic string to 5 beads and thread it through all the hole and tunnels all the way to the gauntlet.

15. Tie the elastic cord to the fingertip, thread it through all the appropriate holes all the way to the end of the palm.

16. Tie the elastic cords to the bridge on the palm tight enough to keep fingers in extension but not too tight.

17. Attach the junction to the ratchet using the junction pin and slide it into place on the gauntlet, locate it around the middle.

18. Tie the strings of the index finger and the middle finger around the suitable pillar in the junction.

Do the same for the ring finger and the pinky.

19. Tie the thumb string to the hole in the ratchet.

20. Make sure that flexion of the hand flexes all the fingers, if needed adjust the ratchet and the strings.

21. Thread the Velcro as seen in the picture (X shape in the palm and straight in the gauntlet)

22. Glue padding to the three braces and the gauntlet.

23. Gather all electronic wires of the sensory system into one heat shrink about 50mm long.

24. Attach the electronic circuit to the gauntlet using screws or hot glue.

25. Attach all the electronic wires to their appropriate terminals as shown in step two.

Step 6: Calibration

Parts and Tools Used In This Step:

· Arduino USB cable.

· Hot glue gun.

· Soldering iron & solder.

· All the printed parts related to the hand.

· Parts A1-B1, AH1-AJ1.

Instructions:

Whenever the Arduino is connected by a USB cable to a computer make sure the battery is completely disconnected.

1. Connect the Arduino to a computer using a USB cable and upload the FSR calibration sketch.

2. Use the serial monitor to extract the resting measurement (maximum value) of each FSR and the measurement of each one under pressure (minimum value) write down this values (10 numbers between 0 to 1024)

3. Open the Sensory feedback 3.0 sketch and change the values in rows 100, 105, 110, 115, 120 according to values from the previous section

4. Save the sketch and upload it to the Arduino.

5. Disconnect the USB cable from the Arduino.

6. Make a power cable for the Arduino using two wires (5V & GND) and the USB head and connect it to the appropriate terminals in the board. Make the cable long enough to reach the spot you want to place your battery in. It is recommended to place it on the top part of the arm using a rubber band.

Make sure the battery wire is wired properly to prevent heating and damage to the Arduino.

7. Use hot glue and attach the two switches to the slots in the cover.

8. Close the cover using the four 2.5X16mm screws.

Congratulations! You have a fully functioning Sensory Feedback Raptor Reloaded

Step 7: Emulator (optional- for Developers Only)

Scale and print all parts:

Parts and Tools Used In This Step:

· 3D Printer.

· Measuring tape.

· Box cutter.

· Printing material (F2).

· Wire cutters.

· Hot glue gun.
· All the printed parts for the emulator.

· Parts A2-E2.

Instructions:

1. Scale (if needed) all the parts to fit your hand (see step one).

2. Print all the parts (list is attached as a PDF file):

3. Cut the threaded rod into 4 pieces (2X11mm, 1X10mm, 1X9mm) make sure you can still thread a nut on the rod.

4. Use to two pins to connect the arm and the palm.

5. Use hot glue to attach to rods to the printed part (the shortest rod fits the shortest bump etc.)

6. Use glue to attach the padding to the palm and the arm.

7. Attach the Velcro to the palm and the arm through the holes.

8. Thread four nuts on the four rods all the way, then thread the palm plug and gauntlet plug and finally thread four more nuts on the four rods. Tighten the nuts around the plugs.

9. Attach the Emulator to the hand using the 8 3X16mm screws.

Step 8: Acknowledgments

1. e-NABLE organization.

2. Haifa 3D- Dr. Yacov Malinovich, Benny Godlin, Oded Salomon, Miriam Kreisler, Yaniv Gershoni, Dr. Hezi Shotland.

3. Department of Biomedical Engineering, Technion- Dr. Oscar Lichtenstein, Aharon elfasi.

4. Virtual-Reality & NeuroCognition Lab- Rotem Bennet.

5. FeelIT- Meital Segev, Gad Konvalina, Walaa Saliba.