Graduation design (Thesis) practice (research) report of Dalian Jiaotong University 2016
Practice (research) report
1. The source and significance of the subject.
In nature, in order to adapt to the changing external environment, after millions years of evolution, the structure of animal’s morphology and function are in continuous evolutionary transformation. Now animal’s dexterous mechanism motion and movement pattern has been developed as an inexhaustible supply of robot imitation. The mechanism movement is been analyzed as the characteristics of biological research, which has become a mimic biological exquisite structure and the key of behavior. How to get the required design really need motion mechanism analysis for all kinds of sports information, which has been indispensable important technology to the bio-mimetic robot design.
In a large number of inspection and analysis of the domestic jumping robot research literature, it can be seen that in the present, there are a wide range of market and application prospect for the hopping robots, both in domestic or overseas. To review the bouncing robot basic theory and the current research status of hopping robot both in domestic and foreign , here we plan to use the spring and the connecting rod mechanism as the design of the robot mechanism design which is based on the frog robot that has been designed already with jumping robot dynamic analysis. In this paper, according to the characteristics of the frog jumping, the establishment of the frog jumping mechanism model by analyzing the movement of the frog.
2. Current situation of the research in our country and abroad
At present, the research of the bionic robot has become a very active factor in the field of modern scientific research. Compared to most of the wheeling or walking mobile robot, jumping robot has a remarkable advantage, because that jumping robot can leap over obstacles. With strong ability of surmounting obstacles, this robot can avoid the risk, so that it can expand the scope of the activities of the bionic robot in some extent, which breaks the limitations of the range of motion of the existing robot. Many research institutions in domestic and overseas have begun to engage a various types of jumping robot research. Raibert, a professor at the Institute of the Massachusetts Institute, who study the technology through the dynamics of biological research, has developed both the two dimension and three dimension jumping and running robots with single foot, double feet or four feet, whose legs is biped and quadruped by the telescopic structure with air spring and driven by hydraulic pressure. Hyon developed a bionic robot dog, whose joint part of the legs equipped with two hydraulic drives to be seen as a muscle, with a spring as a tendon, we can achieve the goal of the jumping. Professor Birth, from the CWRU University of the United States, developed a
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Graduation design (Thesis) practice (research) report of Dalian Jiaotong University 2016
machine crickets whose length is only 2 cm, driven by the artificial muscle, can complete the crawl and jump as well as other actions. Domestic research on bionic robot is becoming more and more sophisticated, at present, the domestic sports for the development of bionic robot mainly contain two drive, one is a wheel or crawler drive, the other is by bionic crawling or walking mode, National University of defense technology has successfully developed the robot of snake shaped.
Through the comparison with the kangaroo, crickets and other animal exercise, it is not difficult to find that the frog has amphibious movement, the jumping movement of a fog can be explosive, the jumping distance of a fog can be very long(can reach 15 times the length of the body). The robot with the jumping ability of a fog can easily cross the ditch and obstacles, so that it has a good adaptability to the environment. Due to this feature, the bouncing robot will play an important role in the exploration of the planet, military reconnaissance and anti terrorist explosion protection and anti disaster relief.
According to the characteristics of the frog, a frog jumping mechanism model is analyzed in the motion of the frog, to design a frog robot model will study through much examples calculation.
Figure 1. Mechanical model of jumping robot.
Through the research, we know that, in the field of bio-mimetic robot, Raibert, a professor at the Institute of technology developed in 1980 that succeed in design the world’s
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Graduation design (Thesis) practice (research) report of Dalian Jiaotong University 2016
first continuously jumping and moving robot with single leg. But the motion of the robot was restricted to the a plane, machine leg is provided with a cylinder, the role of it is just like a spring, making the robot motion similar to a spring of the inverted pendulum. The basic motion model as shown in Figure 1, the structure has the translational degrees of freedom and the rotational degree of freedom in X direction between foot and body. Through the analysis of the kinematics and dynamics calculations, the jumping and landing process, as long as the movement in accordance with the law and properly controlled, the robot can maintain continuity and stability of the jumping movement. At present, the research on the Raibert jump model is now focusing on how to balance the nonholonomic constraint systems.
Another relatively early jumping robot model for the Ac-robot mechanism model and its structure is similar to the inverted double pendulum. The mechanism has a unique rotational degree of freedom and a unique power source, which is located at the joint of the mechanism, the only rotating joint of the mechanism also acts as a power source and a balance arm. The mechanism of the jump is to accelerate its centroid to make it gradually lost contact with the ground at the bottom, the current research on the Ac-robot jump model also focuses on the robot balance control and other aspects of the problem.
Figure 2. A small hopping robot Scout.
Stoeter, from University of Minnesota developed a small hopping robot Scout, as shown in Figure 2. The shape of the robot is a cylinder, with a diameter of 40mm, length 115mm, weight 200g. The hopping robot can go just forward in a flat terrain with two wheels, once encountered the stairs, it can release elastic leg to realize jumping, and the jumping height can reach 35mm. It belongs to the intermittent hopping robot, and is equipped with sensors and cameras; people can communicate with the Scout through wireless radio frequency. Scout
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Graduation design (Thesis) practice (research) report of Dalian Jiaotong University 2016
robot adopts single twisted rope pulling butterfly shape spring to get the energy storage, the robot has limitations for can only realize energy release in site and cannot adjust the take-off posture.
Researchers at Case Western Reserve University learn about the crickets of it’s two different movement patterns by observation and kinematic analysis, and simplify the 3D motion of complex biological dynamics simulation. The simulation results is used for design and control of a bionic cricket robot, its size is only 5cm, the leg is driven by the artificial muscle consisted of polymer tubular fibers, as shown in Figure 3. Artificial muscle fibers within a micro air compressor through inflated, and the micro controller to control the leg micro valve and air compressor, the artificial muscle made taut and contraction movements, drive mechanical crickets walking and jumping.
Figure 3. A bionic cricket robot.
Niiyama, in the University of Tokyo, Japan, who developed a new type of double legged hopping robot named Nowgli, as shown in Figure 4. Based on the mechanical properties of the biological body, the legs are designed to be progressive, and there is a degree of freedom in the hip, knee and ankle joints, which is driven by the McKibben pneumatic artificial muscle. McKibben is similar to the human leg tendon in a two - way arrangement, which allows the legs to have supple and more natural dynamic characteristics. After Nowgli’s expansion, the length of the robot can reach 0.9m. Because the main body parts of the material is a polymer, its weight is only 3kg and can also have a very good strength. The robot can jump on the ground or slope, up to 0.5m, to achieve the impact of the soft landing.
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Graduation design (Thesis) practice (research) report of Dalian Jiaotong University 2016
Figure 4. Double legged hopping robot.
At present, our country has also begun to get the development of the hopping robot. Huangpu Yang, from Shanghai Jiaotong University, presents a robot with flipping motion model with single leg, and has carried on the analysis to the motion mechanism and trajectory planning. Different from the general robot, the robot's motion structure is not to take the spring structure, but only by three rotating joint. In a full motion cycle, the robot can accomplish two walking stages and a flight stage.
Zhuangzhi Liu, from Nanjing University of Aeronautics and Astronautics of hopping robot did related research, multiple robot is presented, theoretical analysis, design, fabrication and experimental research of single bar hopping mechanism and six bar hopping mechanism, analysis the hopping robot motion regulatory sequences planning and control problems. Five kinds of typical jumping mechanism analysis of kinematics and dynamics is going on, as well as the study of impact and energy consumption problems.
In China, Yu Hangqi, from Harbin Industrial University, learned through the analysis of the movement mechanism of locust, carry on by the take-off biological model is simplified, as well as a quadruped jumping robot theory model and also from the point of view of the energy about a quadruped jumping in the mathematical model of the robot kinematics and dynamics analysis. The final design of the two sets were driven by motor and electromagnet based prototype, they also did some experimental research.
Through the study of the bionic robot on a large number of existing reference, method for bionic hopping robot construction can be divided into the bionic mechanism and bio-mimetic materials, mostly existing is bionic mechanism, such as mechanical grasshopper, a robotic dog, and the mechanical cats. Bio-mimetic materials is constructed similar to the
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