Final Project: "Xpresso" Robotic Head For kids with Autism

Background & Concept

Autistic kids are characterized with facial expressions recognition impairment, they can't simply infer from a person's face if s/he is happy, angry or sad.
Researchers have been tinkering around with using robots instead of human therapists with autistic kids, and they found very positive engagement with robots. Autistic kids find it easier to interact with robots than humans because their reactions and expressions are simpler, consistent and less overwhelming.
Milo , Bandit , and Kaspar to name a few, are social robots which were developed with a wide range of interactive abilities, starting from expressing basic emotions, up to talking, dancing and playing games. These capabilities have proven to be useful in developing social interaction skills in children with autism.
For my Fab Academy final project, I developed "Xpresso", an expressive educational robotic head for children with autism. This robotic companion will serve as "facial expressions live guide". Kids can use it to learn various facial expressions.
How it works: A smart flash card is scanned on the robot's front panel to elicit pre-programmed facial expressions from the robot. Each card is unique and can elicit only one of six simple expressions: happy, sad, angry, confused, evil smile and neutral, to help the child learn to recognize human facial expressions.
To develop my final project I used the digital fabrication techniques that I learned throughout my 6 months in Fab Academy: 2D and 3D design for the chassis and mechanisms of the robot, electronics design and productions for the robot's microcontroller, laser cutting for the robot's face, head and neck, 3D printing for the robot's eyes' pan and tilt mechanism parts, and embedded programming to bring the robot's facial expressions to life using RFID tags.

Project Bill of Materials (BOM)

No.	COMPONENT	AMOUNT	UNIT PRICE	TOTAL PRICE	VENDOR
1	Atmega328p	1			RAM(LOCAL SHOP)
2	Crystal 16Mhz/18pF	1	0.25 USD	1.5 USD	FARNELL
3	22 pF Capacitor	2			FARNELL
4	1 uF Capacitor	1	0.05 USD	0.4 USD	FARNELL
5	499 Ohm Resistor	2	0.05 USD	0.05 USD	FARNELL
6	100 nF Capacitor	2	0.1 USD	0.4 USD	Digi-Key
7	Push Button	1			Digi-Key
8	FTDI pin Header	1	0.25 USD	0.25 USD	FARNELL
9	Mifare MFRC522 13.56 RFID tag Reader	1	8 USD	8 USD	>RAM(LOCAL SHOP)
10	9g Servo Motor (Micro)	9	3.6 USD	32 USD	RAM(LOCAL SHOP)
11	RFID Tags	5	0.5 USD	2.5 USD	RAM(LOCAL SHOP)
12	3.3 v Volatge Regulator LM1117	1			RAM(LOCAL SHOP)
13	10 uF Capacitor	4		0.7 USD	RAM(LOCAL SHOP)
14	2x3 SMD Pin Headers	5			RAM(LOCAL SHOP)
15	Power Jack	1	0.2 USD	0.2 USD	RAM(LOCAL SHOP)
16	Power adaptor	1	2.8 USD	2.8 USD	FARNELL
17	LEDs	2			FARNELL

2D & 3D Design of Xpresso

The intial design features for "Xpresso" were:

Eyeballs Mechanism: tilt and pan movement
Eyebrows Mechanism: Up and down movement
Lips Mechanism: seperate right and left corners raise and lower movements
Eyeleds Mechanism: up and down movement
Lower Jaw Mechanism: up and down movement
Neck mechanism: pan and tilt movement

However, these features were reduced later during the integration process to only the first 3 design requirements due to time limitations.

Having these features in mind, it was really challenging to start putting down a design concept for something that complicated on a blank sheet of paper, so when I started the design process I decided to "stand upon the shoulders of giants", building on the design concepts of other people who attempted to design and develop animatronic heads.

Two main robotic heads captured my attention, Kismet and FRITZ .

Kismet was developed by MIT professor Dr. Cynthia Breazeal as the first socially interactive robotic system. Kismet's design concept was intriguing and I intially decided to base my design concept on it, especially the lips mechanism as it animates the lips in a 3D rather than 2D space, facilitating the expression of a range of emotions. However, as I went through the design process, I realized that there were many 3D parts to be designed that will require time for design and cost for fabrication (3D printing). This was the intial design attempts for the robot head:

Afterwards, I decided to shift towards a simpler design concept inspired from FRITZ, which mainly composed of 2D parts of plywood, MDF wood or Acrylic that fit together to form the 3D features of the head. These parts will be designed in 2D and fabricated using laser cutting.

Eyebrows, eyeleds, lips and jaw mechanisms were planned to be animated using servo motors which would be embedded into the 2D parts of the face, head and neck. However, the eyeballs mechanism needed to be designed seperatly in 3D and fabricated using 3D printing.

I started the design process back in the computer-aided design week. I decided to start with designing the eye mechanism first, considering that based on its final dimensions I can design the face, head and neck parts.

To design the eyes' movement mechanism I Googled some designs, and I found an interesting one on Thingiverse: Dasaki Compact Animatronic Eyes. So I based my design concept on it, and redsigned the parts myself using Fusion 360.

This is how the fully assembled mechanism looked like on Fusions 360:

Now that the 3D design of the eye mechanism is done, I can design the "container", the head, face and neck parts. The general design concept is based on FRITZ, however, I redesigned the 2D parts to be simpler and take less time in assembly.

For the head and neck, I designed two 2D sides which contain openings for servo motors that will control the eyeleds' mechanism and jaw mechanism

For the face, I designed two 2D parts, A lower and upper face. The lower face is "hidden" underneath the upper face, as it is the layer where the head-neck sides fits with joints, and eyebrows and lips servro motors are fixed. So it is basically the "messy backstage" of the face! Whereas the upperface is the tidy presentable part of the face.

I needed to create a kind of platform where the eye mechanism is fixed. This platform fits with the head-neck sides.

I designed a simple 2d jaw that completes the upper face's shape while being seperate so that I can potentially animate it a servo motor.

And finally, I designed eyebrows as an essential feature of a human-like face.

When the entire head-neck-face parts are assembled together, it looked like this:

Fabrication Process

For the fabrication process I used 3D printing for the eyes' mechanism parts and Laser cutting for the head-neck-face parts.

3D Printing

For the 3D printing I used Prusa MK3. I needed to slice the parts first and for that purpose I used Cura 4.0 slicer. I did 3 rounds of printing for which I used almost the same printing settings.

I used a layer height of 0.1 mm and for the quality of the print I set the infill to 20%.

The tempterure of the nozel was set to 220 degrees, while the plate's tempterure was set to 70 degrees.

Finally, the printing speed was set to 45 mm/s

I used the same printing settings to print the rings that attach to the eyeballs, however, the printing failed at the rotation arms.

It seems like the printer has "skipped" printing some layers, which led to the failure. After consulting with Mahmoud Kotb, the makerspace manager at Fab Lab Egypt, He noted that the failure is possibly due to the retration distance setting, which is the distance that the filament retracts in the nozel while the nozel moves laterally between objects.

To avoid the failure, which is specific to the white PLA filament I used, I needed to the decrease retraction distance from 0.8 to 0.4 mm, which solved the problem.

I printed the rest of the eye mechanism using the same printing setting, while using a different PLA filament (Golden color).

Laser Cutting

For the second part of the fabrication, I used Laser cutting. I used Plywood of 3mm thickness.

Using LaserWorks V6 software, I prepared the settings for cutting: speed at 30 mm/s, and laser power at 65.

4 minutes later......

Electronics design & production

Electronics Design

Deciding on the kind of microcontroller that I'm going to use required planning for the input and output devices that I'm going to use.

I'm using Mifare MFRC522 RFID Reader as an input device, and 9 servo motors as output devices. For this purpose I decided to use ATmega328P microcontroller, considering that it can control up to 12 servo motors at once.

The design of the microcontroller board is based on Satshakit, however, I needed to customize it for my purposes. Instead of desiging a shield to connect the servo motors to Satshakit input pins and power it externally, I incorporated 10 pin headers (3x1) for 10 servo motors on the board itself, each of which incorporates 3 pins for VCC, GND and signal all in once place.

For the input device (RFID reader module): I incorporated a seperate 7x1 pin header connected to Atmega328P's 9,10,11,12,13,14, GND and 3.3 V output of the voltage regulator.

To power the board, I needed two voltage sources a 5V to power the microcontroller and servo motors, and 3.3V to power the RFID module. For this purpose, I incorporated a power jack to plug a 5V/2 mA power adaptor, in addition, I incorporated an LM1117 3.3 voltage regulator to output 3.3v to power the RFID.

For the purpose of interfacing with the board in the future, I've also added an FTDI pin header to be able to program the board through an FTDI module.

I used Autodesk Eagle software to design the schematic and board of the microcontroller:

Electronics Production

Preparing the board for fabrication, I exported 3 monochrome images for the board: traces layer, holes layer, and frame cutout layer.

Imported each of the 3 layers into Fabmodules to create toolpath for fabrication

For milling the traces I used 1/64 inches endmill, and for both the holes and outline I used the 1/32 inches endmill.

With the help of our instructor Mohamed Kamel, I soldered the board for the first time using solder paste. I simply put a little bit of the paste over the pads, carefully place the components, and simply direct the flow of hot air over the board from a safe distance to make sure that the plastic casing of the components doesn't melt, just the paste would become shiny and solidify once I put the hot air flow away.

And finally the board was completely soldered and ready for testing!

Integration

I started with integrating the eyes mechanism, assembled the printed parts with the servo motors using some 4 mm screws and a screw driver.

Integrating the head, face and neck parts was simple. I justed fitted the parts together, I didn't even need use screws at the joints as I considered the laser kerf in my design.

Embedded programming

Preparing RFID Cards

The algorithm for Xpresso's facial expressions is as follows: an RFID card is present near the front panel, the robot will present a certain expression. This expression is unique to the card's ID.
For this purpose, I need first to read the unique ID for the PVC RFID cards and dedicate each card to a single expression.
But first to be able to work with MFRC522 RFID module, I downloaded and added the MFRC522 RFID library into Arduino IDE as shown below
I connected the RFID module to the RFID pins I dedicated for communication with RFID reader on Satchakit and connected an FTDI module to the FTDI pin header on Satchakit (see connections diagram below)
For the testing of the RFID reader I used a breadboard first, then in the integration I fixed the RFID reader to the back of the front panel.
I used the dumpInfo code, which reads the info on the card and output it on the serial monitor.
I scanned every card, read and recorded the ID from the serial monitor as shown below.
I dedicated a unique ID for every expression:

Expressions: Programming

I needed to drive 5 servo motors, eyebrows (2), lips (2), and pan eyes mechanism (1).
I attached these 5 servos to 5 PWM pins on Satchakit. While I designing the board I dedicated 10 possible PWM pins for driving servo motors, from which I chose 2,5,6, A5 and A4 to control the eyes, eyebrows and lips.
The algorithm goes as follows: First I included 3 libraries, the servo motor library, the MFRC522 RFID library and finally the SPI communication library as this is the protocol that the RFID reader uses for communication.
Next, I needed to dedicate 2 pins on the ATmega328P chip for Reset and serial communication with the RFID reader, which are pins 9 & 10.
As I'm using 5 servo motors, I needed to define 5 myservo variables as well.
In the Void Setup, I included a command for opening the SPI communication with the RFID reader, and the intiation command for the RFID reader itself.
I also included the serial communication commands: Serial.begin(9600); Serial.println(F("Scan the card...")); which I used in the testing phase when I used the serial monitor to send confirmation messages for each expression, however these commands are not essential for the final demo considering that Xpresso doesn't have a screen to show these messages.
Also the Void Setup is where I dedicate 5 specific signal pins for the servo motors that will animate the expressions, I chose pins 2, 5, 6, A4 and A5.
In Void Loop, I included the main algorithm which is a series of if-else if-else conditions, the conditions are checked and if one is correct, the routine within is executed. The conditions are simply that RFID tags IDs have to be identical to one in the if condition.
The routine for each facial expression rotates the servo motors with certain angles, animating the facial features to indicate a certain emotion.
Xpresso is programmed to express 6 different emotions:

Final Project Video

Here is the final demo video for Xpresso!

Acknowledgements

The work of daniele ingrassia, as I redesigned his Satshakit and integrated it into my projects
The work of Instructables user hackintoshlover12, as I used the design concept and mechnisms of Fritz the robotic head as an inspiration source to redesign and create my own
The work of Thingevese user nono78b, As I used the design concept and mechanism of Dasaki Compact Animatronic Eyes as an inpiration source to redesign and create my own
My local instructors at FabLab Egypt, Mohamed Kamel & Mohammed AboelHaggag and FabLab Egypt's general manager Omar Elsafty for their continous support, giving us their valuable time, effort and knowledge.
FabLab Egypt's technical team members Mahmoud Kotb, Mrehan El Shahawy and Mahmoud Aboelnaga for being supportive, and always open for questions and offering help.
My regional Guru Ohadino Meyuhas for his constructive feedback on my work, for sharing his knowledge and for his continous support.
My global evaluator, Santi Fuentemilla, for his constructive comments and feedback.
American Center Cairo (ACC) at the U.S. Embassy in Egypt for partially funding my Fab Academy diploma.
Last but not least, my Fab Academy 2019 classmate Nada Abdelfattah for always sharing her knowledge and expreience without limits. I'm a big believer in peer learning, and from Nada I learned TONs! Thank you my friend :)

License

Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)