01 base up team
I. Introduction
Hello Mr. Zhuo:
We are the base-up team from Shandong University, participating in the negative pressure electromagnetic group of the 18th smart car competition. We adopted the scheme of negative pressure electromagnetic car model independently designed and manufactured.
2. Car model design
1. Overall structure
The car model adopts a dual-drive motor and a four-wheel differential structure. The overall design idea of the car model comes from the Japanese electronic mouse, and some of the details come from the car model structure of X-ray X1. Because the rules allow the addition of negative pressure, so referring to the general idea of the Japanese electronic mouse, the center of gravity of the car model is lowered, the weight is reduced, and four brushless fans are used to provide downward pressure.
Due to our lack of experience in the overall competition and our limited understanding of the overall structure of the car model, we used simulation to determine some approximate structures when we started designing the car model.
▲ 图1.2.1 车模设计界面
For many details after this, due to the gap between theory and reality, we have made and designed experiments to verify and compare, and iterated continuously, such as the comparison between the negative pressure produced by single fan extraction and the downforce provided by four fans; C car model, The comparison between the structure of the D car model and the self-made car model; the gear part of the car model, the parameters such as the number of teeth, the modulus, the transmission ratio of the gear; the position of the fan, etc., through practice to verify and compare the schemes, and constantly iterate the car model.
▲ 图1.2.2 车模最终结构
2. Bottom plate
After selecting this plan, the initial idea is to use the PCB version of the car model as the bottom plate of the car model. Due to the limitations of volume, position, height, etc., the PCB board chooses the main drive integrated plan, and integrates the core board, motherboard, op amp, The driver is integrated on one board, which greatly reduces the size of the whole board. However, due to the strength of the PCB board, the forward-looking will be shaken, which is not conducive to line inspection and element judgment. In the later period, the plan was changed, and the bottom plate was replaced with a carbon fiber plate for support, and a thinner PCB board was placed on it. However, because the selected PCB board is thin and easy to deform, we changed it to a multi-layer carbon board to make the PCB flat and firm. fixed on the carbon plate.
▲ 图1.2.3 底板与控制电路板
3. Top plate
Use 3D printed fixtures to fix four brushless motors on the carbon plate, and place the four brushless ESCs and their assembled power distribution boards on the carbon plate. This method can further strengthen the strength of the bottom plate. . Compared with the four-in-one ESC, the split ESC sacrifices the size advantage, but it has a more flexible assembly method, which is helpful for the adjustment of the car model and reduces the cost as much as possible.
4. Tires
At the beginning of the design, the idea was to use silicone tires, and began to use the silicone tires customized by Taobao. However, because the overall precision of our car models needs to be high, and there are some problems with the accuracy of printing and production, we tried it ourselves and learned how to make it. Silicone tires, improved accuracy.
▲ 图1.2.4 硅胶轮胎
In later tests, we found that the silicone tires did not adapt well to the structure of the car model. So we decided to change the formula for the tires. But since no one else has made this tire scheme, we can only try to explore it ourselves. Since there is no mature technology, we can only continue to buy raw materials to make it ourselves. Finally, we choose a silicone tire skin, which not only has good friction, but also reduces weight.
▲ 图1.2.5 硅胶胎皮
3. Conclusion
The problems encountered by self-made car models are much more than those of finished car models. There are still many parts to be optimized, and the whole production process is not easy, but each of these problems allows us to have a deeper understanding of the hardware of the entire car model. , which is also the advantage brought by self-made car models. When encountering problems one by one, the whole team analyzes, reproduces, and solves them together. From this, we are constantly challenging ourselves. Although it is difficult, when we see a 4m+ car running around the ring during the test, the excitement is great. Exclusive to homemade car models.
▲ 图1.3.1 车模运行情况
I am very grateful to the smart car platform for allowing us to have this unique experience. Facing the self-made car model, I just want to say that although there are great risks and challenges, it also fully demonstrates our problem-solving and innovative thinking. I also hope that more people will try to make their own car models to make this competition more exciting. Although the provincial competition failed, we still really want to show the limit of this car model on the stage of the national competition, and hope to get this opportunity.
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