Introduction: Autistic Children Remote Control
During the 1st Master of Electro-mechanical engineering,
the students are challenged to create a robot for the project of the course Mechatronics by Professor Bram Vanderborght. As a team of three girls, we decided to take the opportunity to work with autistic children.
"Make your choice" represents a project in cooperation with Parhélie Brussels, a private institute for autistic, psychotic or severe neurotic children and adults. The goal is to create a device that gives children with ASD from ages 12 to 18 the opportunity to communicate with computers. Since the children don't speak, the device should help them to interact with people too. From now on, caregivers will not have to choose in name of the children but the children will be able to make decisions autonomously. The main goal is that they are able to pick a song or dinner option, displayed on the computer screens, by themselves.
Since it's interesting to provide the option to reuse the project in other future projects, the possibility of extension will be taken into account. The coding of the computer app will be performed in such a way that the choice options can be extended as wished.
For the design, it's important to take into account that the children are easily distracted, don't have very good motor skills and will probably try to destroy the device. A box is designed, where all the electronics can be stored inside. In order to protect against shocks, the battery is stored in a separate box and the electronic components are soldered on a PCB.
Step 1: First Design
Before thinking about electronic components for the project, it's good to come up with a first design of the box.
Since the electronics have to fit inside the box but the box may not become too big to use as a remote, it's a trial and error process to find fitting dimensions. By means of the Autodesk Inventor Professional 2018 program, a first idea is designed. This way, the provided space for all needed components can be taken into account when searching on the internet.
The box will act as a remote, with 3 buttons, to choose between options displayed on the computer screen. The 2 outer buttons will function as control buttons to switch between the different options. By pushing the third button, an option can be confirmed and cancelled. Since we are dealing with autistic children, it's of high importance to make the box not too complex and distracting and always keep the same convention of colors.
By means of an accelerometer, the left RGB LED button will always display a blue color and the right one will always display a red color, no matter how the remote is orientated. The colors are visible all the time and will vanish for some seconds when a button is pressed. Simultaneously with the button action, the piezobuzzer will make a sound and the vibration motors will let the box vibrate in the child's hands.
To link the action of the buttons with the computer app, the signals are sent to the app by means of a Wi-Fi connection.
The final box has a simple, rectangular shape, provided with 3 holes for the buttons (top box), 2 holes (front and back) to connect the battery charger and Redbear Duo and 4 very small holes distributed on both sides to guarantee that the sound of the piezobuzzer is noticeable. The edges of the box are rounded to prevent that the children can hurt themselves or others.
Step 2: Get Your Components
You will need:
- 3D printer (can be accessed in public FABlab Brussels)
We used the printers available for electromechanical engineering students at VUB.
- Soldering iron and solder
- Colorfabb XT - clear material for 3D printing
Available at: https://colorfabb.com/materials/co-polyesters/colo...
- Redbear Duo
Buy from: https://www.antratek.com/redbear-duo
The Redbear Duo's working voltage is 3,3 V. The other electrical components need to be chosen such that they are able to work on 3,3 V.
- 2 RGB LED Buttons (resistors used for connection at PCB)
Buy from: https://www.aliexpress.com/item/ONPOW-22mm...
Price: € 18
- Accelerometer ADXL345
Buy from: https://www.antratek.nl/tri-axis-adxl345-breakout
This is a digital 3-axis accelerometer that doesn't use a lot of power. We want the battery to last as long as possible.
- Li-IonBattery 1200 mAh
Buy from: https://www.kiwi-electronics.nl/lithium-ion-polym...
Price: € 11,95
A Li-ion battery was chosen, even though this is not the safest type of battery, because the remote has to be charged via micro-USB. Otherwise, the caregivers always have to open the box to replace the batteries.
- Battery charger
Buy from: https://www.kiwi-electronics.nl/usb-li-ion-lipoly...
Price: € 14,90
- 2 vibration motors (Connected together with a resistor and transistor)
Buy from: https://www.kiwi-electronics.nl/vibrating-mini-mo...
- Printed circuit board (PCB) to adjust the electric components
4 resistors of 150 Ohm (2 for each RGB arcade button)
2 resistors of 4.7 kOhm (for the accelerometer)
3 resistors of 10 kOhm (1 for each button)
1 resistor of 100 Ohm (for the vibration motors)
1 PN2222 transistor (for the vibration motors)
2 M2,5x8 screws for the of the board of components
5 M3x8 screws for the of the bottom of the box (4) and the bottom of the battery box (1)
4 M2,5x8 screws for the of the bottom of the vibration boxes (2 for each box)
For the programming part, Java in Eclipse was used to program the app. The Redbear Duo was programmed using Arduino IDE.
Step 3: Solder Electronic Components on PCB
To solder all the components on a PCB board, the connections with the Redbear Duo need to be known. These connections can be visualized in the first picture. All the components used in the project are connected to the input/output pins of the Redbear Duo. To connect the buttons and vibration motors, resistors and transistors are needed. These parts can be visualized in the other 3 pictures. To know which resistors and transistor are used and where they are placed, a scheme and additional notes are provided in these pictures.
Side note: The ports given in the pictures are the ones used in the project. It is possible to choose different ports. Only some constrains need to be taken into account: the SDA and SCL ports of the accelerometer need to be connected respectively to pin D0 and pin D1 of the Redbear Duo. The buzzer and vibration motors need to be connected to a PWM pin.
The hookup guide for the accelerometer can be found on the website of Sparkfun. The communication that is used, is I2C.
Step 4: 3D Print Remote
Once the design is improved, the box can be 3D printed.
For the final product, 5 different parts have to be printed:
- the bottom of the box
- the shape of the box
- the fixation plate of the battery box
- the fixation plates of the vibration boxes (2)
The prototype was designed by means of an Ultimaker 2 3D printer.
The material used for all components is ColorFabb XT.
Step 5: Program the Redbear Duo
While the design of the box is being improved and printed, the micro controller can be programmed.
Most of the input/output pins used to connect the components to the Redbear Duo are already explained in step 3. The rest can be found in the code.
As mentioned before, the colors of the outer buttons need to be adapted depending on the orientation of the box. This is why an accelerometer is used. In the code, the color changes when the x-coordinate of the accelerometer is bigger than 50. This is dependent on the way the accelerometer is placed in the box. Be sure to check the value of the x-coordinate in your device and adapt the code if needed.
To save the battery when the device is not used, the Wi-Fi and LED lights can be switched off. When the box is placed on its right side and both the outer buttons are pushed, the box switches off. To wake the box up, the outer buttons need to be pressed (the orientation does not matter for this action). For this step, it's best to check the value of the y-coordinate when the box is placed on its right side and adapt if needed.
Step 6: Make the App
In order to make the remote easy to use, an app was created in Java. The app is able to communicate with the remote over a WiFi connection. Using the received information from the remote, the app will scroll through options and this way select pictures or play songs. Since the program needs to be expandable, names and categories can be added.
In the first panel, the name of the child that will be using the remote has to be chosen. By using the textfield and buttons on the bottom of the panel, names can be added or deleted.
After choosing the name of the child, the category has to be chosen. If the 'Music' category is chosen, a song will be played when a choice is confirmed.
The last screen is the only screen that will be seen by the child and this is also the only panel that can be controlled by the remote. You can scroll through the pictures by going left or right. If a choice is confirmed by pressing the middle button on the remote, a green frame appears around the image. At this point, it is not possible to scroll to different options. By pressing the confirmation button again, a choice is deselected.
The "Add File" and "Delete File" windows can be used to add and delete images. When adding files in the Music category, two steps have to be followed. In the first pop-up window, the image that has to be shown on the screen can be chosen. In the second pop-up window, the song related to this image has to be chosen. The chosen song has to be mp3 format.
To delete a file, the name of the image has to be selected in the list, that pops up when pressing the "Delete File" button.
Step 7: Assemble the Box
As a final step, the box has to be assembled.
- To give additional strength to the box, foam is used on the inside between the buttons.
Keep in mind that the wires of the buttons need some space too!
- The battery is put in the battery box and the battery fixation is screwed on it.
- The vibration motors are equipped with a thin glue layer, that can be used to fixate them inside the vibration motor boxes. Since the boxes are tiny, a ruler or small object can be used to press the motors a little bit better to the sides of the box. When the motors are fixed, the boxes can also be closed by means of fixations and screws.
- The wires from the buttons and vibration motors are connected to the PCB.
- The PCB can be connected to the 3D printed side pillars by means of screws. The assembly of the PCB has to be performed in such a way, that the Redbear Duo and battery charger are correctly localized in the box (near the holes).
- Finally, the bottom of the box is assembled to the pillars in the corners by means of screws.
Congratulations! When getting to the end of this step, you succeeded to remake the remote controller for autistic children. In this stage of the project, it's recommended to test if everything is working as wished.
Good luck and have fun!
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Please be positive and constructive.