Papers by Author: Bing Li

Abstract: A novel 5-DOF parallel mechanism applied to active vibration isolation is proposed in this paper. And by using Newton-Euler approach we set up models of the kinematics and dynamics of the isolator. Besides, a wide-range giant magnetostrictive actuator (GMA) composed of a GMA and a micro-displacement amplification mechanism is designed for the actuation of the isolator. Finally modal analysis of this isolator is carried out in ANSYS software to testify that the parallel mechanism is suitable for active vibration isolation.

Abstract: A new 5-degrees-of-freedom hybrid kinematic machine(HKM) consisting of a 4-degrees-of-freedom PTS-based parallel kinematics platform with center constraint branch and a serial X axis is developed. The will-be-machined workpiece is mounted on the platform and the spindle movement is driven by the X axis. This new HKM is very different from a conventional serial-type machine. Therefore, a special algorithm that can transfer the cutter location data (CL-data) into machine specific NC commands is essential for the applications of the PTS-X based HKM in real machining of the workpiece with the complicated surface. The workpiece’s location approach on the platform and the orientation transformation of the moving platform relative to the machine coordination system are investigated.

Abstract: Based on the proposed 4PUS-1RPU parallel mechanism a 5-axis Parallel Kinematic Machine (PKM) scheme has been developed and the dynamic characteristics of the PKM have been investigated in detail. To avoid the intensive computation caused by finite element analysis in the research, two typical metamodeling techniques of Response Surface Methodology (RSM) and its artificial neural network enhanced technique were employed as the robust design approaches. Comparing the results obtained from the direct RSM the modeling accuracy by the artificial neural network enhanced RSM can be improved.

Abstract: Ultra-precision raster milling is one of the most significant techniques for the fabrication of high precision components with the surface roughness less than 10nm and form errors less than 0.2 um, without the need for any subsequent polishing. However, no matter how well a machine may be designed, there is a limit to the accuracy that can be achieved. This paper studies the machining errors caused by the diamond tool and the axis motions using Freeform 705G. With an empirical approach, the error sources are separated based on their effects on the surface finish. The main source leading to poor surface finish is identified. This establishes a basis for subsequent error compensation and equipment maintenance.

Abstract: In this paper, a novel parallel mechanism (3-RRRS/UPR) used in flexible fixture with configuration composed of two parallel robots (2-RR and 3-RRRS/ UPR) is presented. First, system modeling including the mobility study is conducted. Then a novel methodology is proposed that makes use of screw theory to analyze the deformation and stiffness of the mechanism: firstly we identified the existence of the deformation of the subchain, in terms of the relationship between the effective screw and deformation screw; then we took the deformation as an infinitesimal motion of the mechanism, and the stiffness matrix corresponding to the deformation can be deduced. Finally the global stiffness matrix of the whole mechanism is modeled by assembling different stiffness characters based on the presented methodology.

Abstract: In this paper a novel constraint calibration technique for Stewart platform based Parallel Kinematics Machine(PKM) is presented. A commercial trigger probe and a developed double-ball bar gauge are employed to aid the calibration. In the measuring process the characterized errors can be obtained by comparing the nominal characterized size calculated by the function using the measuring data with the real size of the double-ball gauge. An optimization approach is used to calculate the PKM structural errors, and these errors can be finally compensated into the control model. The error transferring matrix with regard to the structural error of PKM can be formulated. The calibration efficiency can be improved by the automatic calibration operation with the doubleball bar gauge. The developed calibration system has been applied in the industry where the PKM is used for machining the turbine vane, and the machining quality can meet the requirements of the specifications. The presented calibration scheme is generic to be applied for the wide range of PKMs.

Abstract: A new class of 4-DOF Parallel Manipulator (PM) with five supporting subchains is synthesized based on enumeration method. Targeting at 4PUS-1PPU PM, the inverse kinematics and dexterity analysis are developed, and the geometric parameters are determined.

Abstract: Nowadays faceted reflector design has become popular in automotive illumination systems. The advantage of a compound surface enables it to achieve the required hot spot intensity by directing more than 60% of the generated light towards the road, thereby largely illuminate the area through the aperture. The research is oriented to fabricating the mold insert on ultra-precision raster milling (Freeform 705G). In this paper, the tool path generation method for automotive headlamp reflectors is studied, and a practical gouging detection and avoidance algorithm is proposed. The surface roughness and form accuracy (peak-to-valley height) are then calculated theoretically using mathematical formulae. Through the tool path generation of a small but representative surface patch with a gap, a possible way is finally found to generate the tool path for such a class of freeform surface with special equipment.