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The project described below was developed at the Public University of Navarre by a group of electrical and electronic engineering students. The main aim of this project was to build a mini-sumo robot and in addition, we implemented other functions.
First of all, let's describe the 3 different functions of the robot.
In this working mode, the robot must be able to find and push opponents out of the fighting region. The combat area ground is black with a white stripe around it, so the robot must also be able to detect it in order to function properly.
In the following video, there is a fight simulation with a wood block.
Line follower + grid orientation:
In this working mode, the robot must be able to follow the black line above a white background, so as in the previous working mode, it must be able to distinguish black and white. In addition, the robot must be able to place itself into a grid and be able to move from one place to another. We achieved that aim via software, that is, we made a specific program that monitors the robot's position every time.
In the next video, we can see the robot in this working mode.
For this mode of working, the robot needs to know the location where it starts the probe and the point it has to arrive at. This information is sent by Bluetooth with our mobile phone. For that purpose, we have developed a mobile phone application, using App Inventor, an application design online tool. The designed appearance is in the image below.
Wireless remote control:
This working mode was born from the need for remote control for the different problems our robot has to complete, so we developed it. We created an additional tab in the app we designed earlier to control our robot wirelessly via Bluetooth.
2. Electronic design.
Now, that we know the functions of the robot, we can set up the needs of our robot and based on that, choose the components for the electronic design. So, first of all, let's choose our components.
Sensors: Our robot needs sensors to interact with its environment, in order to work in a correct way. These are the sensors chosen for that aim.
Ultrasound sensor: The robot uses an ultrasound sensor to detect the opponent in mini-sumo working mode.
Infrared sensor: The robot uses two infrared sensors for detecting the colour of the ground.
- LED lights.
RJ12 port. We use it to connect the robot to the computer and programme it.
Bluetooth module: We use it to send information and control our robot with our mobile phone.
Based on the needs of the robot, we determined the number of pins and functionalities of the microprocessor. With that in mind, we chose the PIC16F886.
Except for the motors, the rest of the components work with a 5V supply voltage, so we use a 5V voltage regulator to fix that power supply.
Motors drivers: The motor is controlled by an L293D. This component is formed by two H bridges, which are controlled by the PIC, so in this way, the microprocessor controls the action of the motors.
General switch: For turning on and off the robot.
Button: Used for different functions, such as initiating the fight in mini-sumo working mode.
Passive components: Other components needed to manufacture the printed circuit board, resistors, capacitors...
Once we have selected the electronic components, the next step is designing the printed circuit board and then, manufacturing it. In the following image, we can see the resulting design.
The PCB design is a two-layer design. On top, we have a copper area for the 5V power supply. For its part, on the bottom, we have a GND copper area and all the tracks are on this side of the board. We haven't used vias in the PCB design, so the manufacturing of the board will be easier (our vias aren't plated).
Once we have manufactured it, this is the resulting PCB.
3. Mechanical design.
We use Solidworks software with a university license for mechanical design. The images below show the design.
Once we had our mechanical design, we manufactured it with a 3D printer.
4. Do you want to make your own multifunctional robot?
Making a robot step by step seems to be difficult at first, so we hope this article could be helpful if you are going to face this challenge. During the development and manufacturing of the robot, many problems appeared. But it was a great experience to make a real electronics project and face this problem.
Will you bring yourself to make your own robot, you can build on our robot or improve our designs with your own ideas. For this, we offer you all of our work. So, attached to this article you can find the mechanical design of the robot, the electronic schematic design, printed circuit board design, the bill of materials we have used to make the robot, the full program for the different modes of working, and also, the mobile phone app we have developed.
In the next link, you can watch the full electronic journey developed in the Public University of Navarre, in which our robot and our classmates take part. In that journey, the robots faced the different problems described in this article.