Abstract: four axis aircraft, also known as four rotor aircraft and four rotor helicopter, is referred to as four axis and four rotor. The four propellers of the four axis aircraft are simple mechanisms directly connected to the motor. The cross layout allows the aircraft to obtain the force of rotating the fuselage by changing the motor speed, so as to adjust its attitude. Because of its inherent complexity, there has never been a large commercial four-axis aircraft in history. In recent years, thanks to the development of micro electromechanical control technology, stable four-axis aircraft has attracted extensive attention and has a promising application prospect. In the future, four axis aircraft will be widely used in high-risk fields such as security and construction. Let’s look at the details.
1、 Structural principle of four axis aircraft
The four-axis aircraft is a system with six degrees of freedom of movement in space (translation and rotation along three coordinate axes respectively), but only four degrees of freedom of control (the speed of four motors). Therefore, it is called underactuated system (the complete drive system is only when the degree of freedom of control is equal to the degree of freedom of movement). However, for the attitude control itself (rotating along three coordinate axes respectively), it is indeed completely driven.
Compared with helicopters, four axis aircraft can achieve less flight attitude, but the basic forward, backward, translation and other states can be achieved. However, the mechanical structure of the four-axis aircraft is much simpler than that of the helicopter, and the cost of maintenance and replacement is also very small, which makes the four-axis aircraft have greater application advantages than the helicopter.
Automatic control principle
In order to maintain the stable flight of the aircraft, the four-axis aircraft is equipped with three-direction gyroscopes and three-axis acceleration sensors to form an inertial navigation module, which can calculate the attitude, acceleration and angular velocity of the aircraft relative to the ground at this time. The flight controller calculates the rotation force and lift force required to maintain the motion state through the algorithm, and ensures the appropriate force output of the motor through the electronic controller.
2、 Development direction of four axis aircraft
As the most popular aircraft nowadays, four axis aircraft has attracted more and more attention from science lovers and commercial companies, as can be seen from Amazon’s idea of delivering packages to customers with four axis aircraft. It can be said that the future application prospect of four-axis aircraft is very broad.
The four axis aircraft mentioned here is not a single four rotor, but a common name for aircraft with more than one aerodynamic rotation axis.
The future development direction of four axis aircraft mainly includes the following aspects:
First, it can be used as a new concept vehicle
As early as World War II, the prototype of manned four-axis aircraft had been designed, but because the control technology could not keep up, the aircraft could not be put into practical application because of instability.
Second, in the field of security
With the continuous development of artificial intelligence, four axis aircraft equipped with high-definition cameras and various security equipment will be widely used in the fields of public security, fire protection, family and unit security. Four axis will become extremely intelligent and agile e-police, e-firefighter, e-security and e-housekeeper, perhaps in the near future, You will feel very close and safe because you have a flying home to look after the robot.
Third, the construction field and other high-risk operation environment
Many enthusiasts may have seen the video of four-axis aircraft building buildings displayed at Ted conference. This is a very promising application. Compared with 3D printing a house, it is more practical, flexible and efficient to build a huge building with a group of small four-axis aircraft. Maybe one day you pass by the construction site and see that there is not a group of construction workers busy overhead, It’s a group of buzzing four-axis aircraft working in order. Don’t be surprised at what you see at that time.