Can Tang

Kinematics analysis for a hybrid robot in minimally invasive surgery

This paper focuses on kinematics analysis for the 7-DOF (degree of freedom) hybrid robot in minimally invasive surgery. The serial structure of the hybrid robot has three DOF; the parallel structure of the hybrid robot has four DOF. First, the traditional method ‘D-H method’ is used to try to solve the kinematics of hybrid robot, but without success. Then a kinematics modeling method based on the ST (Spinor Theory) is presented. This method is named METM (Multi-layer Exponential Transformation Method). The process of solving the inverse displacements for all joints is analyzed. With this method, the joint displacements of 7-DOF hybrid robot are calculated. The METM method can be applicable for the kinematics of many hybrid robots, especially for redundant robots with more than six DOF.

Hand Segmentation Based on Skin Tone and Motion Detection with Complex Backgrounds

Hand Segmentation is the first problem need to be solved in hand recognition system. Currently, most hand gesture recognition system is based on simple background, or requests the recognizer on glove in special color, which gives human–computer interaction some restrictions. This paper researches the gesture segmentation technology based on complex backgrounds, and gives a method combined with skin tone detection and motion detection. By experiments on the images captured by home security robot, this method can get accurate hand segmentation of all the images. This paper lays the foundation of gesture recognition on the home security robots.

A pneumatically-actuated transferring robot for industrial forge manufacturing using visual inspection technology

This paper presents the development and evaluation of a pneumatically-actuated transferring robotic system that uses visual inspection technology. The objective of this research is to implement the manufacturing automation in a customized industrial forging process. The robot has 5-DOF with a 2-fingered gripper placed on the gantry mechanical structure stage. Furthermore, the robotic system consists of two digital cameras for the visual inspection, which are utilized to test the temperature and the posture of the forging ingot. The required grasping force of the gripper and the accurate position regulation are obtained by pneumatic actuators. The control of the pneumatic actuators is based upon the use of programmable logic controllers (PLC). Subsequently, the temperature and perpendicularity detection capabilities of the visual inspection system are analyzed. Finally, experiments have been carried out to evaluate the performance of the presented robotic system.

Rapid planning method for robot assited minimally invasive surgery

The traditional space mapping and surgical planning method for surgery are time-consuming, and the accuracy of positioning is not high. This paper aims to present a practical and fast way for planning. In the session of visual orientation for spatial location, Micron Tracker camera and self-calibration template are used for positioning; in the session of tracking and locating for four markers on patient and robots template, the coordinates of them are extracted automatically; in the session of DICOM medical image processing, the contour of the tumor is extracted automatically, in terms of the seed filling algorithm, contour tracking algorithm and the B-spline fitting function. Coordinates transformation from the image space to the camera space and to the robot space can be completed rapidly and precisely through this method. Experimental results show that the traditional from 25 to 30 minutes planning time for the entire operation can be reduced to 5 minutes; the space mapping accuracy can be improved from the traditional 5mm to 4mm now.

An Algorithm for Reconstruction of Surface from Parallel Contours and Its Section Contour Extraction in any Cutting Plane

To obtain reconstruction of surfaces from a given contours stack, this paper presents a new algorithm based on MC-algorithm, which solves the problem that 3D surface model cannot be built because the first/last contour has no previous/next contour information, or there are only isolated contours. Meanwhile, the algorithm is applied to extracting section contour of the 3D model in any cutting plane. The algorithm does not need to do as following: traverse and rebuild each triangle of the 3D model, obtain the points of intersection with the cutting plane, and link all points of intersection to get the contour in cutting plane. The algorithm divides the cutting plane into rectangular grid and gets isoline in each marching rectangle directly, without considering the problem of connections of all points of intersection. The 2D sectional contour can be obtained directly after finishing calculating isoline in the rectangular grid.