Javier Vicente Sáez was born in Barakaldo (Bizkaia, Spain) in 1978. He finished his studies of Industrial technical engineering at University of Deusto in 1999. After that, he obtains the degree of telecommunication engineering in 2001. Since 2001, he is lecturer of the telecommunication department at University of Deusto.
At the same time, Begoña Garcia Zapirain and he form the Advanced Signal Processing group, in which he works as researcher. He obtains the Phd in computer science in 2016.
On Wednesday 17 we assist the First lesson with Neil Gershenfeld. It has been a pleasure to meet the MIT Team, other students and FabLabs. In that first day we had the opportunity to receive information about Principles and Practices, everything about FabLabs global network main idea. We find also the Fab Charter in the class schedule, FabLabs rights and responsibilities.
The assignment this week was to plan and sketch a potential final project, so I made some sketches around my idea. Basically, the main idea for my final project is: Modular Robot Curiosity.
In these times there is a lack of interest of the bachelor students in studying engineering. The students in bachiller have to choose between the human and the scientific branch. If they do not choose the scientific branch they can not study engineering. The few students who want to study engineering face another problem, they do not know how to differentiate each type of engineering. In Spain there are a lot of different engineering degrees and the student don´t know to choose between them.
To avoid this problem my faculty is planning action to achieve three goals.
My idea is to design a practical workshop based in a modular robot. In each workshop five groups will contest to see who sets the best robot. There will be tree different challenges: velocity, strength and agility. The students can change different items in the robot:
The teams can choose between different types of wheels (Diameter,thickness, material..). So the will have to argue which is better for each of the challenge. The same for the propulsion system, they can choose between different types of gears. They will have to discover which one provides more velocity or more strength. These changes will have to be quick, so a plug-and-play system will be used, probably using magnets.
In the market exists a lot of educational robot kits, but all are focused in programing. None of the kits in the image allows
a quick change of the components, without using a screwdriver or other tool.
What I want to achieve in a modular system that allows to exchange the parts and modify your physical behavior, be quicker, be stronger...
In this form in a two-hour session students can discuss aspects of engineering such as:
You can find my final project scheme in the image below:
The chasis of the robot has been designed in SolidWorks. In the next picture a render of the design can be shown. The wheels and the gear suppor have hole to include magnets to ease the change of this components.
Click in the list to change the 3D visualization file:
The main part is the chasis this element have been cutted with the laser cutter and made in wood.
The next step is to put the gear holder. This part has magnets to hold the gear. This part also has a hole to host an optocoupler to be able of count the revolutions of the engine.
After that is possible to mount the gear engine, this part have two pieces to hold the DC motor and also have some gears to change the revolution ratio. The gears used in this project have been designed in week2-Computer-Aided-Design.
In the next picture four neodymium magnets can be shown.
In the next picture the battery holder and the gear can be shown joined to the chasis.
In the next picture the steering holder have been added to the chasis.
Now the servo motor holded have been placed.
Finaly the bridge of the steering system have been added.
In the next picture the final robot can be shown. The wheels and the filaflex wheel cover were designed in the week6.
In the mount moment a problem was detected, a piece hole was to small to introduce the bearings and was redesigned.
To control the robot a circuit board has been designed. The robot must be controled by a remote APP through Bluetooh and in a future wifi connection to send data to the cloud will be added. Becouse of that an ESP32 microcontroller has been selected, this microcontroller incorporate BLE and wifi in the same SOC. The energy is take from a 3.7V lipo battery so a lipo battery charged have been added to the design. The chip BD6211F is the motor driver that has been selecter to control the Motor and the TC1262 is the 3.3V regurator choosed. The reason to choose these components is the power lipo power source. The regulator have a low drop voltaje of 400mV that permit provide a 3.3V output from a 3.7V input. The full schematic can be shown in the next picture.
In the next picture the designed PCB can be shown. The lipo charger circuit is in the top lef part. In the bottom lef part there is the motor driver. The ESP32 SOc is in the top right part. The paths in blue are bridges that will be done using wire because it was not posible to do the board in one side. These path are the input and output signals from the ESP32. The fact of not routing this parts permit to check the board before conecting the inputs and the outputs.
The resulting board have a very good finish, without any important fault.
I began to soldering the board.
First I solder a few componens, the battery connector, the regulator and the buttons and I tested then before soldering the microcontroller.
When I almost finished the soldering I began to test the microcontroler. The button of the corner permit to select the flash mode and the other is the reset.
Once the power supply was checked the bridge wires were added.
Another wire was added because the light sensor was in a pin of the ADC2 and it is not possible use the ADC2 if you want to use the BLE. So I had to solder one wire from the light sensor to he pin that use the ADC1.
The remote control has been implemented using AppInventor. This application was designed in week13. The reason to choose this option is that AppInventor is a very good educational tool that permit to teach mobile Application development very easy to young people.
The aplication has in the right part a touch pad to control the movements of the robot and in the left a panel to show the telemetry from the robot.
The block diagram permit the connection between the mobile and the robot through a BLE connection.
Thist part of code allow the recepcion of the telemetry from the robot.
This part of code center the ball in the middle of the pad and began the scanning.
This code move the ball when is pressed the touchpanel.
This code send the ball to the middle when the touchpanel is released.
This code send the motor and steering values to the robot every 250ms.
Whe BLE deviced are detected they are added to the selection list.
The ESP32 has been programed using the Arduino IDE. The reason of selecting the arduino IDE is again the facility to teach programing to young people that they have never programmed. The aplication use a BLE service with two caracteristic. The first characteristic is a write characteristic to send the motor and steering information from the mobil. The second characteristic is a notification characteristic to send the data from the light sensor and the temperature sensor to the mobil. The data is send every 2 seconds.
The ESP32 does not have a native servo motor control library so I have use this library.
#include <BLEDevice.h> #include <BLEServer.h> #include <BLEUtils.h> #include <BLE2902.h> #include <ESP32_Servo.h> #ifdef __cplusplus extern "C" { #endif uint8_t temprature_sens_read(); #ifdef __cplusplus } #endif uint8_t temprature_sens_read(); #define DIR1_CHANNEL 2 #define DIR2_CHANNEL 3 // use 13 bit precission for LEDC timer #define LEDC_TIMER_13_BIT 13 // use 5000 Hz as a LEDC base frequency #define LEDC_BASE_FREQ 5000 #define dir1Pin 14 // GPIO pin used to Dir1 #define dir2Pin 12 // GPIO pin used to Dir2 #define servoPin 15 // GPIO pin used to connect the servo control (digital out) #define lightPin 34 BLECharacteristic *pCharacteristic1; BLECharacteristic *pCharacteristic2; BLECharacteristic *pCharacteristic3; bool deviceConnected = false; int lightValue = 0; int servo = 0; int motor = 0; float temperature=0.0; Servo myservo; // See the following for generating UUIDs: // https://www.uuidgenerator.net/ #define SERVICE_UUID "4fafc201-1fb5-459e-8fcc-c5c9c331914b" #define CHARACTERISTIC_UUID1 "beb5483e-36e1-4688-b7f5-ea07361b26a8" #define CHARACTERISTIC_UUID2 "beb5483e-36e1-4688-b7f5-ea07361b26a9" #define CHARACTERISTIC_UUID3 "beb5483e-36e1-4688-b7f5-ea07361b26aA" class MyServerCallbacks: public BLEServerCallbacks { void onConnect(BLEServer* pServer) { deviceConnected = true; }; void onDisconnect(BLEServer* pServer) { deviceConnected = false; } }; class MyCallbacks: public BLECharacteristicCallbacks { void onWrite(BLECharacteristic *pCharacteristic) { std::string rxValue = pCharacteristic->getValue(); String cadena = rxValue.c_str(); if (rxValue.length() > 0) { int intcadena = cadena.toInt(); motor = intcadena / 1000; servo = (intcadena - motor * 1000) ; Serial.print("Motor: "); Serial.print(motor); Serial.print(" Servo: "); Serial.println(servo); if (motor == 50) { ledcWrite(DIR1_CHANNEL, 0); ledcWrite(DIR2_CHANNEL, 0); } else if (motor < 50) { ledcWrite(DIR1_CHANNEL, 0); ledcWrite(DIR2_CHANNEL, map(motor, 50, 100, 0, 8191)); } else if (motor > 50) { ledcWrite(DIR1_CHANNEL, map(motor, 0, 50, 8191,0)); ledcWrite(DIR2_CHANNEL, 0); } myservo.write(map(servo, 0, 100, 50, 130)); } } }; void setup() { Serial.begin(115200); Serial.println( myservo.attach(servoPin, 500, 2400)); //Setup PWM Channel for Dir1 ledcSetup(DIR1_CHANNEL, LEDC_BASE_FREQ, LEDC_TIMER_13_BIT); ledcAttachPin(dir1Pin, DIR1_CHANNEL); //Setup PWM Channel for Dir2 ledcSetup(DIR2_CHANNEL, LEDC_BASE_FREQ, LEDC_TIMER_13_BIT); ledcAttachPin(dir2Pin, DIR2_CHANNEL); //Setup Servo //Stop Motors and Center ledcWrite(DIR1_CHANNEL, 0); ledcWrite(DIR2_CHANNEL, 0); myservo.write(90); // Create the BLE Device BLEDevice::init("DeustoAstroBot"); // Create the BLE Server BLEServer *pServer = BLEDevice::createServer(); pServer->setCallbacks(new MyServerCallbacks()); // Create the BLE Service BLEService *pService = pServer->createService(SERVICE_UUID); // Create a BLE Characteristic pCharacteristic1 = pService->createCharacteristic( CHARACTERISTIC_UUID1, BLECharacteristic::PROPERTY_READ ); pCharacteristic2 = pService->createCharacteristic( CHARACTERISTIC_UUID2, BLECharacteristic::PROPERTY_WRITE | BLECharacteristic::PROPERTY_READ ); pCharacteristic3 = pService->createCharacteristic( CHARACTERISTIC_UUID3, BLECharacteristic::PROPERTY_READ | BLECharacteristic::PROPERTY_NOTIFY | BLECharacteristic::PROPERTY_INDICATE ); pCharacteristic1->addDescriptor(new BLE2902()); pCharacteristic2->addDescriptor(new BLE2902()); pCharacteristic3->addDescriptor(new BLE2902()); pCharacteristic2->setCallbacks(new MyCallbacks()); // Start the service pService->start(); // Start advertising pServer->getAdvertising()->start(); Serial.println("Waiting a client connection to notify..."); } void loop() { if (deviceConnected) { lightValue=analogRead(lightPin); Serial.printf("*** NOTIFY: %d ***\n", lightValue); String valueTexto = (String) lightValue; temperature=(temprature_sens_read() - 32) / 1.8; String tempTexto=(String)temperature; String texto=tempTexto+";"+valueTexto; pCharacteristic3->setValue(texto.c_str()); pCharacteristic3->notify(); } delay(2000); }
The first test was to check the motor and the gears. I was afraid of the influence of the magnets with the motor, but it was all right. I checked the motor with a power supply setting the voltage to 3.7V, as can be shown in the video the consumption of the motor is about 276mA.
The next test was to probe the servo motor and the steering using the designed board. Has can be shown in the video it works ok.
The motor controlled by the designed board also was tested.
The next step was to test the light sensor and see if it detects well the light changes.
The next video is the test with BLE activated, the sensors and the actuators. I had to make a change in the board to be possible all work well together. It is not possible to use the ADC2 when the BLE is enabled it must be used the ADC1. So I had to solder a wire between the light sensor and a pin in the ESP32.
The final test was to try all together.
This project is oriented to promote engineering studies at schools. So we need to go to schools with the robot, a notebook, a phone and other accessories. So all this components are transported in a ruggedizedcase that can be shown in the next picture.
In the first level the notebook and the phone are placed.
In the second level the robot, wheels, gears, usb cable and other accessories are placed.
The students can take the robot and begin the contest.
In the next video the unboxing can be shown.
The choosed license for this project is the AFL license.
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The next list are the componens outsite the fablab inventory that have been used in the project.
