Key Engineering Materials Vol. 649

Abstract: The effects of entrance length on performance and flow characteristic of EHD gas pump has been experimentally examined in this study. A 61.8mm-in-diameter EHD gas pump with eight evenly spaced emitting electrodes and flush mounted on the tube inner wall is used for this investigation. The experiment is conducted for two applied voltages 19 kV and 20kV with positive polarity. Several (L/D) ratios are used aiming at picking the appropriate length to achieve highest ionic discharge and maximum pump performance. Results show that the lowest (L/D) ratio gives the best pump performance with highest discharge managed.

Abstract: This paper proposes a machine vision-based, servo-controlled delta robotic system for solenoid housing placement. The system consists of a charge-coupled device camera and a delta robot. To begin the placement process, the solenoid housing targets inside the camera field were identified and used to guide the delta robot to the grabbing zone according to the calibrated homography transformation. To determine the angle of solenoid housing, image preprocessing was then implemented in order to rotate the target object to assemble with the solenoid coil. Finally, the solenoid housing was grabbed automatically and placed in the collecting box. The experimental results demonstrate that the proposed system can help to reduce operator fatigue and to achieve high-quality placements.

Abstract: This work presents multi-functional robot arm gripper design along with vision and tactile sensor for efficient grasping and manipulation tasks. The design emulates human’s hand fingers structure using linkages and direct drive through slider-crank mechanism transmission. The structural elements are optimized for a finest performance in motion and force transmissibility of the gripper fingers. The main future of this design is its reliability to grasp and manipulate unknown object while its system complexity is reduced. The gripper has a tool change fixture incorporated into its palm, which will reduce time wastage and do assembling in one go. The gripper is equipped with two cameras in its palm; subsequently it will efficiently seek the target object and perform its prehensile task with intelligently determined grasping force.

Abstract: This paper presents a concept selection methodology, inspired by the Verein Deutscher Ingenieure (VDI) model and Pugh's weighted matrix method, for designing climbing robots conceptually based on an up-to-date literature review. The proposed method is illustrated with a case study of ongoing research, the investigation of an adaptable and energetically autonomous climbing robot, in Loughborough University.

Abstract: The effects of the rotating speed of the spindle, the number of the porous medium inserted into the partially porous aerostatic journal bearing and the thickness of the bearing gap on the characteristics of the bearing such as the pressure distribution, the load carrying capacity and the stiffness of the bearing were studied. Based on the finite volume method and the pressure-velocity coupling scheme of the SIMPLE algorithm with the standard k-ε turbulent model, the CFD software was used to solve the Navier-Stokes equations to calculate the pressure field in the bearing gap. The computed results revealed the faster the spindle rotated, the higher the gap pressure. As the gap thickness increased, the gap pressure, the load carrying capacity and the stiffness of the bearing decreased. The more the porous inserts, the higher the gap pressure and the load carrying capacity, but the less the bearing stiffness would be.

Abstract: Nine kinds of chamfered main cutting edge nose radius tools were used in turning of high-strength carbon-fiber-reinforced-plastics (CFRP) materials to study the cutting temperature of tip's surface. A new cutting temperature model using the variations of shear and friction plane areas occurring in tool nose situations are presented in this paper. The frictional forces and heat generated in the cutting process are calculated by using the measured cutting forces and the theoretical cutting analysis. The heat partition factor between the tip and chip is solved by using the inverse heat transfer analysis, which utilizes temperature on the K type carbide tip’s surface measured by infrared as the input. The tip’s carbide surface temperature is determined by finite element analysis (FEA) and compared with temperatures obtained from experimental measurements. Good agreement demonstrates the proposed model.

Abstract: Automatic surface defect inspection within mass production of high-precision components is growing in demand and requires better measurement and automated analysis systems. Many manufacturing industries may reject manufactured parts that exhibit even minor defects, because a defect might result in an operational failure at a later stage. Defect quantification (depth, area and volume) is a key element in quality assurance in order to determine the pass or failure criterion of manufactured parts. Existing human visual analysis of surface defects is qualitative and subjective to varying interpretation. Non-contact and three dimensional (3D) analyses should provide a robust and systematic quantitative approach for defect analysis. Various 3D measuring instruments generate point cloud data as an output, although they work on different physical principles. Instrument’s native software processing of point cloud data is often subject to issues of repeatability and may be non-traceable causing significant concern with data confidence.This work reports the development of novel traceable surface defect artefacts produced using the Rockwell hardness test equipment on flat metal plate, and the development of a novel, traceable, repeatable, mathematical solution for automatic defect detection and quantification in 3D. Moreover, in order to build-up the confidence in automatic defect analysis system and generated data, mathematical simulated defect artefacts (soft-artefact) have been created. This is then extended to a surface defect on a piston crown that is measured and quantified using a parallel optical coherence tomography instrument integrated with 6 axis robot. The results show that surface defect quantification using implemented solution is efficient, robust and more repeatable than current alternative approaches.

Abstract: An ultrasonic motor using thrust ball bearing with dimple structure on the friction surface has been proposed. The bearing balls are rotated by the friction force caused by the ultrasonic vibration of the stator, and transfer torque to the rotor. The dimple structure on the sliding surface can hold the ball position and rotate the balls and the rotor without a retainer. The newly proposed motor can avoid the friction loss between balls and the retainer. The balls of 2.4 mm in radius are used and the radii of the curvature of the dimples of 2.0 mm and 3.0 mm are used in this research. The radius difference changes the contact condition between the balls and the dimple structure. Fundamental motor characteristics are measured and discussed.

Abstract: Rehabilitation robot is usefully to improves walking ability on patients with gait disorders. Over the last decade, rehabilitation robot device replaced the training of overground and treadmill. The purpose of this study was to compare the differences in muscles activities of simulated human leg while walking on two gait rehabilitation robots: the exoskeleton rehabilitation robot and the end-effector rehabilitation robot. We have built models of simulated human leg, exoskeleton rehabilitation robot and end-effector rehabilitation robot. The results showed that rectus femoris and tibialis anterior muscles of the simulated human leg were more active while walking on the exoskeleton rehabilitation robot. The results of this study may provide technical improvement for gait rehabilitation robots, so that lower limb muscles movement can be more correctly achieved for normal individuals during gait rehabilitation training.