1.Body control Skateboard design ideas
Safe and intelligent transportation tools. Research has found that most of the electric skateboard tools on the market are two-wheeled balance vehicles, electric scooters, unicycles, and so on. The two-wheeled balance scooter is large in size, inconvenient for users to carry, and the price is high. Electric scooters are slightly larger and heavier. Although there are foldable scooters, the folding mechanical structure is unstable and prone to mechanical failure; unicycles are sizable, but they are more difficult to learn. How to solve the trouble of walking too far and having trouble driving.
At present, the existing electric skateboards use wireless Bluetooth for remote control operation, and the user holds a remote control in his hand to perform forward and parking operations. This method requires an additional remote control, and the remote control is easily interfered by the external environment. Once the remote control fails and the skateboard is not controlled, it will bring unpredictable danger to the user.
This leads to thinking about whether it is possible to design an electric skateboard that can judge the needs of users while fully guaranteeing the safety of users. That is, an electric skateboard with thinking ability. An electric skateboard that is manipulated by sensing the user's weight transfer, or is called an intelligent somatosensory control electric skateboard. It works like this: by stepping on the front of the skateboard with one foot, the system can judge the weight distribution on the skateboard and control the speed. Stepping forward and leaning forward indicate acceleration, and stepping backward and leaning backward indicate braking. This means that the control of the skateboard is completely controlled by the user's body, and it also meets the needs of people's movements.
Skateboarding is a sport that young people love very much. Our work combines the interests of young people and integrates advanced technology into skateboarding. It makes the use of skateboards more convenient, simple and safer, so that young people gradually understand the artifacts of somatosensory pressure control and balance control during the use of skateboards.
Due to the addition of intelligent pressure somatosensory control and balance control methods, the learning of skateboard becomes very simple, and it can even be said that it can be used in 1 minute. Therefore, our work is also a very convenient transportation tool. Compared with the popular transportation tools on the market, our skateboards are lighter (the current weight is slightly heavier, and the later optimization can achieve a weight of 7~9kg), and it is very portable. convenient. In some occasions that are too close to drive or too far to walk, such as commuting to and from work, taking express delivery, shopping in supermarkets, etc.
2.Description of the hardware part
The key to body control electric skateboard is the collection and acquisition of somatosensory data. Somatosensory control is not like the somatosensory control of the balance car on the market. Most of the somatosensory control of the balance car on the market uses the MPU6050. This MEMS gyroscope sensor obtains the attitude angle, and then realizes the balance control by controlling the motor. The somatosensory control we mentioned here is obviously collecting gravity data, specifically, collecting the position of the center of gravity of the person on the skateboard. Furthermore, the distribution of pressure data is collected. Next, for the skateboard product, should it be like a 3D pressure-sensitive mobile phone? Not really.
Obviously, there are two ways of thinking. One way of thinking is to install the sensor on the two fixed points of the front and rear bridges. Another idea is to install the sensor on the panel of the skateboard. The specific one is better and needs to be tested. In the research market, the only skateboard that supports pressure control is zboard2. This skateboard uses a sensor mounted on the panel of the skateboard.
This is the second key part, the hub-type brushless motor with Hall is selected. Dual drive scheme. There are two schemes for motor control. One is to rely on the existing BLDC drive chip to complete the control of a single BLDC, and the other is to write the control code of the BLDC by yourself. Choose the latter here. Let's write the BLDC code ourselves. After all, I'm still a bit basic, and the six-step reversing method is not difficult. One stm32f103rct6 can realize the control of two bldc.
The peripheral circuit of the main chip is relatively simple, and the pin assignment diagram of the main chip is given here.
The power supply battery is 36V, 15V is obtained through DCDC, 5V is obtained by linear voltage regulation (78M05), and 3.3V is obtained by linear voltage regulation (LM1117-3.3V) again. The power supply system is a relatively common solution.
Material list (BOM list)
Main components: stm32f103rct6, stm32f103c8t6, hx711, ir2010s, ir2181s, acs712, etc.
The bibuff platform is also very convenient, with BOM quotation, procurement, PCB manufacturing, steel mesh, and SMT one-stop service, and the quality is reliable and the price is fair.
It is also very cost-effective for users who make small batches of samples. For the somatosensory electric skateboard product, personally feel that there may be a larger market in the future.