Abstract: With the development of my country's economy and the improvement of scientific research level, artificial intelligence technology and robots have gradually entered our daily life. Many industrial fields have begun to use robots to produce products. There are two main types of robots currently in use, one One is a serial robot, and the other is a parallel robot. Compared with a serial robot, a parallel robot has the advantages of more precision, greater work intensity, and higher sensitivity. This paper discusses the stiffness and static analysis of parallel robots in depth. With the increase of research on parallel robots in my country's scientific research industry, parallel robots will also have a more complete theoretical system in the future, which will be widely used. It is widely used in domestic and foreign manufacturing fields.
Artificial intelligence and robotics are important and difficult research areas in the field of domestic and foreign scientific research in recent years, especially the research on the stiffness and statics of parallel robots. Common parallel robots have rod-supported parallel robots and rope-tracted parallel robots. The steel-belt mechanism parallel robot is a new type of mechanism that requires rigorous testing and analysis before use.
1 Main structure analysis of parallel robot
The research and development of parallel robots in my country is relatively late, but compared with serial robots, parallel robots have greater rigidity and are more stable in practical applications. Parallel robots do not need to carry motors with them when they are working. Small, and therefore the inertia generated during the work process is much smaller than that of parallel robots. From the perspective of the working structure of the parallel robot, the parallel robot is mainly divided into a rod support structure and a rope traction structure. Large, but the main force is the traction force of the rope, and the force is relatively single. With the research of scientific researchers, the new steel belt parallel structure has also begun to be applied in the working process of parallel robots. The steel belt parallel structure combines the advantages of the rod support structure and the rope traction structure. The steel belt parallel structure has advantages in practical application. The working space is large, and the movement speed is faster than that of the parallel robot of the rod support mechanism. Compared with the rope traction mechanism, the structure of the steel belt parallel mechanism is simpler, and it is easier to perform mechanical and dynamic analysis.
Stiffness is the main index to evaluate the quality of parallel robots, including static stiffness and dynamic stiffness. The stiffness is related to the structure of the parallel robot, and is also related to the various parameters of the robot. There are many factors that affect the stiffness of the robot. Therefore, it is not enough to achieve the best stiffness of the parallel robot. If you want to design the stiffness For better parallel robots, it is necessary to conduct research on their structure and various parameters, and only after multiple comparisons can a parallel robot with higher rigidity be developed.
3 Parallel robot rod support parallel mechanism
The pole-supported parallel mechanism is the most commonly used mechanism for parallel robots. It has the advantages of strong rigidity and high load capacity. Compared with the rope traction mechanism, it can be used in a wider range. Compared with the steel belt parallel mechanism, its rigidity is greater. At present, the comparison of the stiffness of parallel robots in my country is based on the parallel mechanism supported by rods. The stiffness is divided into static stiffness and dynamic stiffness:
The existing static stiffness analysis methods include model analysis and performance analysis. The model analysis method is to establish a model to simulate the relationship between the force and the deformation of the stressed object. The static stiffness analysis is based on the analysis of the static stiffness model to analyze the static stiffness performance of the parallel robot when it is working. The following data are for reference.
The physical meaning of the data obtained from the dynamic stiffness analysis is different, and there is no unified standard to regulate these data, so a unified standard can greatly promote the research department's research on the stiffness of parallel mechanisms. Dynamic stiffness is the ability to reflect the maximum force that a parallel robot can withstand without deformation under motion, and it is the standard to measure whether a parallel robot can resist external turbulence. At present, there are few studies on dynamic stiffness at home and abroad. In the development process of parallel robots, dynamic stiffness is very important. Dynamic stiffness directly determines the stability of internal components of parts processed by parallel robots. The dynamic stiffness detection of the parallel robot production process can make people understand the entire force situation of a component during the processing process.
4 Parallel mechanism of rope traction for parallel robot
Compared with the rod-supported parallel mechanism, the rope-tracted parallel mechanism of the parallel robot has a one-way force bearing capability, and can only bear tension, not pressure. Therefore, the stiffness analysis of the rope traction parallel mechanism is generally carried out under the condition that the rope traction mechanism bears the tension. The rope traction structure is very easy to be affected by other external forces during the stiffness test. Therefore, if the rope traction mechanism is to be The analysis of stiffness and statics under the condition of only tension requires repeated experiments. The rope traction parallel mechanism is in a state of dynamic balance when it is working. Therefore, when analyzing the static stiffness, it is necessary to carry out continuous tests according to different positions. , in the process of testing, it not only consumes time, but also consumes a lot of funds. Therefore, it is very necessary to construct a simple model to test the static stiffness.
5 Steel belt parallel mechanism of parallel robot
There are no major research results on the steel belt parallel mechanism in China. Most of the domestic understanding of the steel belt parallel mechanism comes from foreign research results. When analyzing the steel belt parallel mechanism, a model is constructed. In this model The main device is the steel belt as the kinematic pair. The steel belt has a certain degree of elasticity and a certain curvature on the surface. It will deform to a certain extent when it is subjected to a large force. The whole mechanism is relatively stable when the pressure is small. When the pressure is too large and exceeds the limit of the force that the entire steel belt can bear, it will cause the entire parallel robot to lose balance. Therefore, when using the steel belt parallel mechanism inside the parallel robot, it is necessary to first analyze the maximum force that the steel belt can bear. After measuring the critical value for the second time, the steel belt parallel mechanism is applied to the parallel robot. The steel belt parallel mechanism is different from the rope traction mechanism and the rod support mechanism. The steel belt parallel mechanism can not only bear greater pressure like the rod support mechanism, but also can withstand greater tension. Its force is multi-directional. After many studies and analysis, it is found that the maximum pressure that the steel belt parallel mechanism can withstand is related to the material and curvature of the steel belt. If the pressure on the mechanism is greater than the critical value of the force of the steel belt, the parallel robot will lose its internal balance.
The steel belt parallel mechanism is used inside the parallel robot. During the high-speed movement of the parallel robot, there will be slight vibration due to the small quality and insufficient thickness of the steel belt. Outside the parallel robot, it will appear as the vibration of the robot's behavior. Therefore, for the steel belt It is very important to study the dynamic stiffness and static stiffness of the parallel robot mechanism. The data obtained through a large number of simulation experiments shows that the static stiffness is mainly based on whether the steel belt mechanism is out of balance in parallel, and the dynamic stiffness is related to the vibration frequency and size of the steel belt. From this we can know that the stiffness when the parallel robot loses balance is the smallest, so during the use of the parallel robot, the vibration of the steel belt due to excessive pressure should be minimized. If the pressure is too large and exceeds the maximum pressure that the steel belt can withstand, it will cause the steel belt parallel mechanism to deform. It is meaningless to perform static analysis when the steel belt parallel mechanism is deformed. The relevant data obtained are consistent with the rope traction structure. The static analysis does not make much difference.
6 Relevant conclusions drawn from the study of three parallel mechanisms
① After a large number of experimental simulations, we can know that the stiffness of the rod-supported parallel mechanism is relatively large. When performing stiffness analysis, it is simpler to use relevant models to calculate and analyze the stiffness of the rod-supported mechanism, and the accuracy of the calculated results is higher. However, in many cases, the model of the rod-supported parallel mechanism is relatively large, and the results obtained in different states are also different when performing stiffness analysis. This method is not feasible to measure the stiffness of the parallel mechanism supported by the rod, which is not conducive to the future research on the stiffness and statics of the parallel robot. When establishing related models for static stiffness analysis, most of the focus is only on the elastic size of the components, ignoring the influence of other factors, which will reduce the accuracy of model prediction. Moreover, the current basis for evaluating the stiffness of parallel robots is different at home and abroad, and there is no accurate standard for evaluation. Relevant researchers in statics research need to make a specification for the basis of static stiffness evaluation and the use conditions and scope of the evaluation. Scholars still need to apply various methods and experiments when researching and analyzing the stiffness and statics of parallel robots, so as to obtain more accurate data and theories.
②The rope traction parallel mechanism of the parallel robot is only subjected to a single pulling force when working, so the scope of application of this mechanism at home and abroad is small, and it is only used in the field where the parallel robot only bears pulling force. After a lot of research and literature search, it is found that, The stiffness of the rope traction mechanism is only related to the stiffness of the rope and the maximum tensile force it can withstand. During the working process, the stiffness of the mechanism increases with the increase of the tension and decreases with the decrease of the tension. In addition to being affected by the tension, It is also related to the elasticity of the rope of the rope traction mechanism. Compared with the parallel mechanism of the rod support mechanism and the steel belt, the rope traction mechanism is more likely to be disturbed by external conditions when performing stiffness and statics studies. Therefore, the rope traction parallel connection When the parallel robot of the institution is researched, it is necessary to overcome the interference of external factors on the rope. The difficulty in analyzing the stiffness and statics of the rope traction mechanism is that the rope is easily disturbed by external forces and deformed, but a special algorithm can be used to calculate the errors caused by these factors, and the relevant data and conclusions obtained It is also relatively accurate.
③Steel belt parallel mechanism has a special structure, which can withstand tension like a rope traction mechanism, and can also bear pressure like a rod support mechanism, but compared with a parallel robot with a rod support mechanism, the stiffness of a parallel robot with a steel belt parallel mechanism is smaller. Although the steel belt parallel mechanism can withstand various forces, the steel belt of the parallel robot with the steel belt parallel mechanism is easy to lose balance when it is working, and the steel belt after losing balance is prone to vibration. Therefore, when the parallel robot uses the steel belt parallel mechanism It is necessary to analyze the unbalance and cause of the steel belt parallel mechanism first, and then analyze the stiffness and statics of the parallel robot of the steel belt parallel mechanism, so that the data obtained are more accurate. More research and experiments are needed to obtain more scientific research results. At present, there are few researches and use cases on parallel robots with steel belt parallel mechanisms in China and even the world. The relevant research conclusions of the parallel robot with rod support mechanism and the parallel robot with rope traction mechanism should also be used for reference in the related research of mechanics.
With the development of science and technology, people's demand for robots is also increasing. At present, many researchers and scholars at home and abroad have achieved preliminary results in the research on the stiffness and statics of parallel robots, but the research results can no longer meet the current needs for the use of parallel robots. There are many problems in the use process. Therefore, it is necessary to conduct more in-depth research on the stiffness and statics of parallel robots. Due to the large volume of parallel robots, there are still many inconveniences in using model analysis methods in the research process. In the next step of research on the stiffness and statics of robots, the research methods must be improved. With the development of science and technology, diversified research methods can soon be applied to the stiffness and statics of parallel robots, and can be faster and easier. Get the data you want to analyze, greatly improving work efficiency. The relevant research on parallel robots can not only solve the aging phenomenon of our country's population and solve the problem of labor shortage, but also make the processed products more refined.