Week 1

In recent years, people have a lot of research and development on remote control vehicles. We want to do more research and change in this field of remote control vehicles to make it more convenient, so our aim this time is to do a project that can directly control the small car through gestures.

This project is called Gesture Controlled Car which can directly control the direction and route of the car by people’s gesture. After wearing the corresponding sensing glove, people can send instructions to the car by bending different fingers to make the car act according to the instructions. In our initial vision, we can achieve the communication between car and glove through media settings such as radio frequency, Bluetooth or WiFi, and Arduino is used to import the corresponding communication code into Bluetooth.

                                                          Figure 1. Two parts of the project

As it can be seen in Figure 1, the whole project was divided into parts, so the team was also divided into two groups. One responsible for the flex sensor part and most work of transmitter, the other one complete the motors control part and some receiver part. 

Working process

Motors Group:

In the morning, we are planned to assemble the car base. However, we forgot to take the screwdrivers to the lab. Therefore, one of us had to go back to his home to take the screwdrivers. In addition, at that time, we employed DC power supply to test the motors one by one to make sure every motor worked.

After we got the screwdrivers, we start to assemble the car base. At the beginning, we found that four motors are the same, which means if the same voltage was applied to four motors, the wheels on the left side and right will rotate in different direction. As it shown in Figure 2 below, if we apply same voltage to four motors, the motors on the left hand side will rotate clockwise, and the motors on the right hand side will rotate anticlockwise. In summary, it will confuse us when we control the input voltages.

                                                          Figure 2. Rotation direction of motors

Consequently, we change the assemble direction for the motors on different sides of the car to avoid this problem. However, as it show in Figure 3 and Figure 4, the rotating part is on one side of the motor, and it will result in a small distance between two forward wheels, and also for back wheels. In addition, it will cause the car always run will a small angel. Therefore, we have to dismantle and assemble direction for the four motors in the same direction, and it makes us tired.  

Figure 3. DC motor

                                                                 Figure 4. Rotation diagram

After that, we completed the assemble work for the car base, the top side and bottom side of the car base are shown Figure 5 and Figure 6. 

                                                     Figure 5: Top side of car base

                                                          Figure 6: Bottom side of car base

In the afternoon, we try to control the motor by arduino. In the plan, in order to protect arduino and control the rotation direction of the motors L298N chips was chosen as motor driver, so it was studied. However, when we try to order L298N chips, it was told that the L293D chips have the same function with L298N chips, and they can supply them right new. Consequently, we decide to employ L298N chips, and more time was spent in studied the principle of L293D chip.

As it can be seen in Figure 7, inside L293D, there are some invert gates to avoid the reverse current, which can protect arduino. Therefore, we can connect the two outputs of chip to the two inputs of the motors, and simply control the rotation direction of motors by changing the ‘high’ and ‘low’ of the input digital signal. 

Figure 7: Logic diagram of L293D

After learning, we write a simple code which is shown Figure 8 to test whether the chip works. In this code, the motor will rotate clockwise for five seconds, and it will rotate anticclockwise for five seconds. However, the lab would close at that day, and we have to stop the work.   

Figure 8: Simple codes of test chip and motor

Flex sensor Group:

Our main device flex sensor didn't arrive, so we had to start with the communication element. After searching the Internet for information and comparing several communication devices, we decided to use Bluetooth communication. Our main task this week is to test each Bluetooth's work, that is , whether they can enter the AT mode successfully. Connect Bluetooth to our phones and upload the Arduino test code into Bluetooth, the red light on Bluetooth flashes every two seconds. It confirm that our Bluetooth enter the AT mode successfully and work. The AT test code is shown in Figure 9.

                                                                          Figure 9. AT test code

problem

Although our Bluetooth enter AT mode successfully, a large problem is Bluetooth can't accept signals and it disconnected whenever we send signals on our mobile phones. We changed the circuit, data wire, Arduino and Bluetooth but the problem still existed. We didn't solve the problem and the lab closed that day, so we decided to find out the reason next time.