A survey of research on the hottest two wheeled se

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Summary of research on two wheeled self balancing robot

Abstract: the two wheeled self balancing machine is a special wheeled integrated robot, which has multivariable, nonlinear, strong coupling, parameter uncertainty and other dynamic characteristics. It has certain scientific research and practical application value to discuss it in depth. This paper summarizes the research status of two wheeled self balancing robots at home and abroad, analyzes the problems existing in the research, and points out the development trend of self balancing robots

the integral robot has become an important branch in the field of robot research because it has broad application prospects in all walks of life. According to the classification of its adjustment mode, there are wheel type, crawler type, leg type, propulsion type, etc. among them, the wheel type adjustment robot is widely used because of its low cost, simple structure and control, and high energy utilization. Therefore, the practical value and theoretical value of wheeled integrated robot are very high

the two wheeled self balancing robot (as shown in Figure 1) is a special wheeled adjusting robot. Its concept was proposed in the 1980s. It belongs to one of the wheeled robots and combines the idea of autonomous adjustment. Its operating principle is derived from the control principle of inverted pendulum. Through the establishment and analysis of its dynamic model, we can know that its system is a nonlinear, strongly coupled, multivariable and naturally unstable system. It is an ideal model to test various control theories, and has become a province at home and abroad. Research hotspot

because this robot can balance itself, its ability to adapt to terrain changes is expanded, and its motion is flexible, and its travel speed and tilt acceleration can be adjusted. Through the differential input of two wheels, the advantages of zero radius of rotation and U-shaped rotation can be realized. And it has simple structure, flexible movement, and is suitable for working in narrow and dangerous space. Therefore, it has a wide application prospect in both civil and military. Therefore, the research of two wheeled self balancing robot has strong teaching value and wide market application value

1. Research status at home and abroad

the related research of two wheeled self balancing robot began in the 1980s. According to the introduction of the manufacturer, Professor Ichio Yamato of the Department of human automation of Tokyo Telecom in Japan put forward a similar design idea. He applied for a technical patent in 1987 and passed a patent application in Japan in 1996

in 1995, Dean Carmen, a famous American inventor, began to develop Segway. At present, this highly confidential new invention was not announced until December 2001. It was officially listed in the U.S. market in March 2003. Segway's unique dynamic stability technology is similar to the balance ability of the human body. Five cheap homomorphic gyroscopes, tilt sensors, high-speed microprocessors and motors detect the body posture 100 times per second, measure the driver's center of gravity, instantly complete the calculation, and make minor adjustments at a frequency of 20000 times per second, which can automatically maintain balance in any state and terrain. At present, Segway has three main product series HT, XT and GT, but Segway HT, which was first introduced, is further subdivided into a variety of sizes, outputs and uses according to demand differences

in 2002, Aldo D Arrigo and others of Ruishi Federal Institute also studied a wireless controlled two wheeled integrated robot similar to Segway. The robot is 650m high and weighs about 12kg. The maximum speed can reach 1.5m/s and can climb 30 degrees. The two wheels of the robot are arranged coaxially and driven by independent motors. The robot detects the tilt acceleration of the body of the robot and the tilt acceleration of the robot through tilt sensor and tilt sensor technology. Each motor has a coding disk to detect the speed of the motor, so as to obtain the acceleration and inertia force of the robot. The state feedback linear control and pole assignment method are adopted, which can realize the balance, but it can't return to the upright state by itself

in 2003, David p.anderson of Southern Methodist University in the United States independently designed the two wheeled integrated robot nbot, which was rated as "cool robot of the week" by ASA's. The robot has large volume and complex structure. Its main design idea is to drive the wheel to move in the direction of the upper part of the robot, and keep it below the center of gravity, so that the robot can maintain balance. The robot uses two kinds of sensors for feedback control. Tilt sensors are used to measure the tilt of the center of gravity, and coders are installed on each wheel to obtain the position information of the robot. The robot adopts fuzzy control method, which can achieve balance, but it can't return to upright when it falls to the ground by itself

the University of Western Australia also designed a self balancing two wheel car in 2003 to study sensor information fusion based on Karman filter, which uses lor control and pole placement to realize the balance control of the car

around 2004, Japan began to carry out commercial research on the two wheeled self balancing robot. The initial design was similar to the shape of Segway in the United States, but in 2005, it had its own new product Segway pmp-2. Its external shape and most parts have been greatly modified, but most experts believe that these changes have made the performance of Segway's products worse and can achieve balance, However, you can't return to standing upright by yourself

since then, many robot enthusiasts abroad have also begun to study the two wheeled self balancing robot and published their research results on the Internet. Therefore, many similar robots have appeared on the Internet, such as LEGO self balancing robot and self balancing sliding robot, which have achieved balance control

domestic research on two wheeled self balancing robot started relatively late

in October, 2002, Taiwan's Economic Department collected relevant information about Segway from the industry bureau, provided it to domestic manufacturers for reference, and encouraged manufacturers to develop similar products using the special surplus of government scientific research. Two rounds of self balancing robots have been developed by the National Institute of ergonomics and electrical engineering in Guli, Taiwan. The signals of gyroscope and encoder are obtained by personal computer through wireless communication. After being processed by fuzzy control and other control algorithms, the robot sends corresponding control signals to FPGA, and FPGA sends corresponding pulse signals to control the robot to move forward and backward. After five years of continuous improvement, the robot can complete a variety of actions, but it still does not achieve upright

in the same year, the College of mechanical and electrical engineering of Henan University of science and technology and Luoyang north Enterprise Group Co., Ltd. conducted research and development on the project. The first prototype was produced in July, 2003. It consists of high-performance microprocessor, attitude sensor, intelligent software and other control systems to achieve the walking balance control of the car. The subsequent walking balance control test verifies the rationality and effectiveness of the control system and control strategy design. The project is at the domestic leading level in the balance control technology of two wheel walking

in 2003, a number of professors, doctoral tutors, doctors, master's students and undergraduates in the Department of automation and the Department of mechanics of the University of science and technology of China jointly developed and completed the self balancing electric scooter (free mover), which is a practical two wheel balance and has been practical. The car uses the inverted pendulum control principle to keep the car body balanced all the time. Under the control of the embedded CPU in the car body, collect the data of the balance sensor and the speed and acceleration sensors, calculate and output the PWM signal through the established system mathematical model and control algorithm, and automatically control the torque of the two servo motors to keep the car body balanced and automatically advance, retreat and turn according to the deviation of the center of gravity of the human body

in 2005, Yin liang of Harbin Yucheng University also announced on his blog that he had made a two wheeled integral robot, sway, which used the dual axis acceleration sensor ADXL202 Technology launched by ad company to detect the inclination of its lower body, used the reflective infrared range height sensor to measure the distance, and used the linear control method to realize the balance of the robot

in addition, National Taiwan University of science and technology, Shanghai Jiaotong University, Xi'an University of Electronic Science and technology, Harbin Institute of technology, Beijing University of Posts and telecommunications, Beijing University of Aeronautics and Astronautics, Beijing Yuye University and many other schools have also started research on two wheeled self balancing robots, and have achieved some results. At the same time, many domestic machines are interested in saving. He also began to study self balancing robots, and announced his own research results on the Internet. Among them, the research team composed of three Tsinghua university graduates has made giant achievements. The chegway self balancing robot they studied has reached the fourth generation, and they have also cooperated with Rijiang electric appliance to prepare for the input and output

2. Existing problems

the limitations of the above research are also reflected in the following aspects: (1) it is not possible to achieve the upright of a two wheeled self balancing robot; (2) Due to the limited overall size and adjustment range of the robot, as well as the limited size of the balance mass, only limited stable adjustment can be carried out under the load condition, which limits the bearing capacity of the two wheel self balancing robot. (3) Due to its bearing capacity and the current battery technology, there is also a certain problem in the energy supply of the two wheeled self balancing robot. (4) In reality, people who drive a two wheeled self balancing robot are different in body shape, weight and other aspects, because they can't combine technical analysis and modeling with people well when designing, can't well analyze the mechanical essence when people drive a two wheeled self balancing robot, and can't better realize its control mechanism

3. Outlook

due to the market positioning of the two wheeled self balancing robot, it is required to continuously develop and improve in the following aspects:

(1) dynamic balancing the balancing process that the dynamic balancing robot can recover from the fallen state to the straight balance state by itself without human help. We call it autonomous dynamic balancing. In terms of mechanical additionality, when there is no help, an external force or torque that overcomes the gravity of the robot body must be generated in some way to make the robot change from overturning to straight state, and more importantly, the magnitude and direction of this external force or torque must be controllable. Therefore, it is necessary to study how to produce the balance mechanism of this force or torque, so as to realize the upright of the two wheeled self balancing robot

(2) how to maintain the balance of the lower body system under various motion states such as no-load, load, forward, backward, rotation and braking, in various environments compared with aluminum and steel, and for drivers of different shapes and weights

(3) considering the increase of energy consumption efficiency, when selecting the control scheme, we can consider the minimum integral of the absolute value of the control action phase as an important criterion to ensure that the energy consumed by the moving unit distance is the minimum on the premise of meeting the dynamic performance of the system. This means that under the same condition of battery power consumption, the car can move farther, which is important for product design

therefore, high stability, low energy consumption, high adaptability and high bearing capacity will be the main development trend and inevitable requirement of the two wheel self balancing machine

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