Theoretically, cars can be designed to rotate to turn. This is actually an application of rear wheel follow-up steering technology.
For example, this JEEP concept car has four wheels that can rotate in different directions, not to mention turning, and it can even spin in place. However, this design is definitely more complex and costly, and the subsequent maintenance costs will also increase.
Car front-wheel steering seems to form one of people's inherent impressions of cars. Citro?n's widely spread patented rear-wheel steering steering technology is actually not a black technology. Long before this, vehicles have been able to The realization of multi-wheel steering at the same time was only applied to off-road vehicles. In the early days, the structure was complex and bulky. Citro?n's patented solution is simpler and pioneers the use of rear-wheel steering technology in passenger cars. Rear-wheel steering has many benefits. It not only improves the ground adhesion performance when turning, reduces roll, reduces the turning radius, and makes the vehicle more flexible.
The current mainstream rear-wheel steering technology can be divided into active and passive. Active
I think it should be called four-wheel active steering more appropriately, because these four wheels are indeed actively changing directions to participate in turning.
This control strategy uses vehicle speed as the standard for control. When driving at low speeds and turning, the rear wheels turn in opposite directions to the front wheels. In this way, the car has a tendency to spin in place, making cornering more sensitive and faster.
You cannot control it like this when driving at high speed, otherwise it will easily lead to loss of control. At this time, the rear wheels turn in the same direction as the front wheels, which is suitable for high-speed merging. The rear of the car follows the front of the car, which can reduce the lateral force of the vehicle body when changing lanes and increase stability. Passive
Passive rear wheel follow-up steering relies on the deformation of the suspension system to compress the bushing when turning, causing the rear wheel to deflect slightly, improving the flexibility of cornering. For example, everyone is talking about Lao Fukang's rear wheel follow-up steering.
In fact, rear wheel follow-up steering technology has been around for a long time, but the design is relatively complex and the applicable conditions are limited. Compared with the increased design and maintenance costs, it is not cost-effective at all. In addition, the current turning method is enough to meet the needs of cars, so there is no need to make such a design. Therefore, only a few cars are equipped with this system. On the one hand, it can indeed improve some of the vehicle's dynamic performance. On the other hand, it also improves the technical level of the vehicle.