Yang Yiyong

Control unit of the directional drilling system

Rotary steerable systems (RSS) permit downhole directional control whilst continuously drilling in rotary mode. Rotary-steerable systems possess clear advantages both technologically and economically. The control principle of the servo platform in directional drilling system was studied. A control system composed of eccentric cam, dynamotors, platform control axis and electronic storehouse was designed. The inclination of wells was measured using acceleration sensors and a gyroscopes sensor. Experiments results show that the platform could keep itself stabilized and has good controllable and visible characteristics. Moreover, the system still has good tracing capacity when the drilling parameters change in a wide range.

Finite element analysis on factors influencing the clamping force in an electrostatic chuck

As one of the core components of IC manufacturing equipment, the electrostatic chuck (ESC) has been widely applied in semiconductor processing such as etching, PVD and CVD. The clamping force of the ESC is one of the most important technical indicators. A multi-physics simulation software COMSOL is used to analyze the factors influencing the clamping force. The curves between the clamping force and the main parameters such as DC voltage, electrode thickness, electrode radius, dielectric thickness and helium gap are obtained. Moreover, the effects of these factors on the clamping force are investigated by means of orthogonal experiments. The results show that the factors can be ranked in order of voltage, electrode radius, helium gap and dielectric thickness according to their importance, which may offer certain reference for the design of ESCs.

Auto-focusing motor control and image processing of the somatic cell test system

Somatic cell have a key effect on the quality of milk. A test instrument has been developed, it can rapidly and accurately test the quantity of somatic cell for milk. Based on the analysis of milk adhesion behavior, the test system can complete a series of complicated work, such as auto-focusing and image processing. Auto-focusing is an integrated of the grayness and Laplacian operator integration. Image processing includes automatically feeding films, classification, edge identification, image collecting and processing. The results of experiments have showed that the test system can satisfy the need of milk somatic cell test, and it has characteristics of automation and high testing precision.

Control strategies and topological invariance of human prehension

Control strategies and topological invariance of human prehension are discussed through the analysis and comparison of upper-limb reaching-grasping tasks. Five subjects were asked to perform different reaching-grasping tasks with different indices of difficulty, and the movements were captured using a Vicon 3D motion analysis system. Topological invariance was observed in the trajectories of different task performances. After normalization, the trajectories of the hand had very close patterns for different reaching-grasping tasks. Synergy control in the reaching-grasping movements of the upper limbs was also found among the different joint angles. Despite joint redundancy, the joint angles can be fitted using the same format of functions proposed in this study. The parameters in the function can be taken as a characteristic feature of reaching-grasping movement patterns.