Coaxial Twin-shaft Magnetic Fluid Seals Applied in Vacuum Wafer-Handling Robot

Compared with traditional mechanical seals,magnetic fluid seals have unique characters of high airtightness,minimal friction torque requirements,pollution-free and long life-span,widely used in vacuum robots.With the rapid development of Integrate Circuit（IC）,there is a stringent requirement for sealing wafer-handling robots when working in a vacuum environment.The parameters of magnetic fluid seals structure is very important in the vacuum robot design.This paper gives a magnetic fluid seal device for the robot.Firstly,the seal differential pressure formulas of magnetic fluid seal are deduced according to the theory of ferrohydrodynamics,which indicate that the magnetic field gradient in the sealing gap determines the seal capacity of magnetic fluid seal.Secondly,the magnetic analysis model of twin-shaft magnetic fluid seals structure is established.By analyzing the magnetic field distribution of dual magnetic fluid seal,the optimal value ranges of important parameters,including parameters of the permanent magnetic ring,the magnetic pole tooth,the outer shaft,the outer shaft sleeve and the axial relative position of two permanent magnetic rings,which affect the seal differential pressure,are obtained.A wafer-handling robot equipped with coaxial twin-shaft magnetic fluid rotary seals and bellows seal is devised and an optimized twin-shaft magnetic fluid seals experimental platform is built.Test result shows that when the speed of the two rotational shafts ranges from 0-500 r/min,the maximum burst pressure is about 0.24 MPa.Magnetic fluid rotary seals can provide satisfactory performance in the application of wafer-handling robot.The proposed coaxial twin-shaft magnetic fluid rotary seal provides the instruction to design high-speed vacuum robot.

Modeling of large scale solar cell handling robot with belt-driven flexible arms

To increase the competition of the solar energy collection system, the size of the solar panel module during the manufacturing process is being increased continuously. As the size of the solar panel increases, the size of the robot to handle the panel increased also. The change in scale of the robot inevitably results ill the amplification of the adverse effect of tile flexure. The main source of the flexure in the large scale solar cell panel handling system is the long and thin fork fingers of the [land and the solar cell panel. In addition, tile belt-driven actuator system used by most of the large scale panel handling robot is another significant source of the vibration. In this paper, the flexible multi body dynamic model of a large scale solar cell panel handling robot, which is being designed and constructed with the help of Kyung Hee University, is developed. The belt-driven system in the robot is also modeled as flexible system and included ill the robot to represent the actual vibration characteristics of the actuator system. C 2013 The Chinese Society of Theoretical and Applied Mechanics. [doi： 10.1063/2.1301310]

Image moments-based visual servoing control of bagged agricultural materials handling robot

Manual handling is less efficient and sometimes even hazardous to humans in many areas,for example,agriculture.Using robots in those areas not only avoids human contact with such dangerous agricultural materials but also improves working efficiency.The motion of a robot is controlled using a technique called visual servoing that uses feedback information extracted from a vision sensor.In this study,a visual servoing method was proposed based on learning features and image moments for 3D targets to solve the problem of image moment-based visual servoing.A Gaussian process regression model was used to map the relationship between the image moment invariants and the rotational angles around the X-and Y-axes of the camera frame(denoted asγandβ).To obtain maximal decoupled structure and minimal nonlinearities of the image Jacobian matrix,it was assumed two image moment features,which are linearly proportional toγandβ.In addition to the other four standardized image moment features,a 6-DOF image moment-based visual servoing controller for the agricultural material handling robot was designed.Using this method,the problem of visual servoing task failure due to the singularity of the Jacobian matrix was solved,and it also had a better convergence effect for the part of the target image beyond the field of view and large displacement visual servoing system.The proposed algorithm was validated by carrying out experiments tracking bagged flour in a six-degree-of-freedom robotic system.The final displacement positioning accuracy reached the millimeter level and the direction angle positioning accuracy reached the level of 0.1°.The method still has a certain convergence effect when the target image is beyond the field of view.The experimental results have been presented to show the adequate behavior of the presented approach in robot handling operations.It provides reference for the application of visual servoing technology in the field of agricultural robots and has important theoretical significance and practical value.

A Small Simulated Logistics Transfer Robot Car Structure Design

As a new product of the development of modern science and technology,the research and development of logistics robot has become the focus of social attention.Robot sorting and handling is the designated project of Jiangsu University Robot Competition.According to the requirements of the competition,this paper designs a kind of logistics robot trolley which can identify and grab materials according to a given path and transport them to a predetermined location.The mechanical structure design,driving motor selection and mechanical checking calculation of the car are mainly completed.According to the later experiments,the results show that the desired results can be achieved.

Hanging force analysis for realizing low vibration of grape clusters during speedy robotic post-harvest handling

Mechanical damage induced by vibration during harvesting and post-harvest handling could decrease the quality,quantity,and shelf life of the fresh grape cluster.Usually,fresh grape clusters are harvested by gripping and cutting from the main rachis in the present robotic harvesting system,then transported towards the basket during post-harvest handling.However,serious cluster vibration and corresponding berry falling may occur during the robotic transportation of hanging grape clusters.Therefore,this study was designed to perform experimental and theoretical hanging force analysis to explore the vibration mechanism of hanging grape clusters during robotic transportation.A lead screw lathe with an attached linear actuator was used to investigate the effects of four different speeds(0.4,0.6,0.8,1.0 m/s)with four acceleration levels(6,8,10,12 m/s2)on the vibration of the hanging grape cluster.By the experiments,the peak hanging force of the grape cluster at the start,constant speed,and stop phase of the actuator was recorded using a single axis force sensor,and the cluster’s swing angle was measured with a digital camera.The experimental results showed a linear relationship between the swing angle and hanging force of the cluster at the start and stop phase of the actuator.The multi-stage cluster’s vibration during robotic transportation was observed,and the behavior of cycled damping after a sudden stop of the actuator was found.The simulated results of hanging force of grape cluster in damping phase were agreed with experimental results with R2 more than 0.90 at an optimum acceleration of 10 m/s2.To conclude,this research provides theoretical basics for understanding the complex vibration mechanism of the hanging cluster fruits during speedy robotic transportation operations with low-loss of berry drop both on industrial and farm levels.