Effect of weight perception on human performance in a haptic-enabled virtual assembly platform

Virtual assembly platforms (VAPs) provide a means to interrogate product form, fit and function thereby shortening the design cycle time and improving product manufacturability while reducing assembly cost. VAPs lend themselves to training and can be used as offline programmable interfaces for planning and automation. Haptic devices are increasingly being chosen as the mode of interaction for VAPs over conventional glove-based and 3D-mice, the key benefit being the kinaesthetic feedback users receive while performing virtual assembly tasks in 2D/3D space leading to a virtual world closer to the real world. However, the challenge in recent years is to understand and evaluate the addedvalue of haptics. This paper reports on a haptic enabled VAP with a view to questioning the awareness of the environment and associated assembly tasks. The objective is to evaluate and compare human performance during virtual assembly and real-world assembly, and to identify conditions that may affect the performance of virtual assembly tasks. In particular, the effect of weight perception on virtual assembly tasks is investigated

A new methodology to evaluate the performance of physics simulation engines in haptic virtual assembly

Purpose – In this study, a new methodology to evaluate the performance of physics simulation engines (PSEs) when used in haptic virtual assembly applications is proposed. This methodology can be used to assess the performance of any physics engine. To prove the feasibility of the proposed methodology, two-third party PSEs – Bullet and PhysXtm – were evaluated. The paper aims to discuss these issues. Design/methodology/approach – Eight assembly tests comprising variable geometric and dynamic complexity were conducted. The strengths and weaknesses of each simulation engine for haptic virtual assembly were identified by measuring different parameters such as task completion time, influence of weight perception and force feedback. Findings – The proposed tests have led to the development of a standard methodology by which physics engines can be compared and evaluated. The results have shown that when the assembly comprises complex shapes, Bullet has better performance than PhysX. It was also observed that the assembly time is directly affected by the weight of virtual objects. Research limitations/implications – A more comprehensive study must be carried out in order to evaluate and compare the performance of more PSEs. The influence of collision shape representation algorithms on the performance of haptic assembly must be considered in future analysis. Originality/value – The performance of PSEs in haptic-enabled VR applications had been remained as an unknown issue. The main parameters of physics engines that affect the haptic virtual assembly process have been identified. All the tests performed in this study were carried out with the haptic rendering loop active and the objects manipulated through the haptic device.CONACYT (National Science and Technology Council of Mexico) research grant CB-2010-01-154430 and EPSRC/IMRC grants 113946 and 11243

An Energy Consumption Approach in a Manufacturing Process using Design of Experiments

Modern manufacturing facilities are facing several challenges, such as increasing demand of products with higher flexibility created in the shortest time. Manufacturers must also deal with the efficient use of energy, emission reduction and comply with increasing requirements in sustainability, leading to the development of more efficient processes and systems. A novel environmentally benign manufacturing approach is presented, where production processes and systems move towards a reduced carbon footprint impact. At the factory level, especially in machining, nearly 90% of carbon footprints occur due to the electricity demands of machine tools. At the machining stage, electrical demand is associated with machine start-to-stop, and significantly higher amounts of non-cutting energy are consumed compared with the actual material removal energy in end-milling, resulting in a low efficiency process. The purpose of this paper is to explore machining strategies by analysing energy consumption using Design of Experiments at the material removal rate, to compare cutting trajectories according to parameters, such as spindle speed, feed rate, depth of cut per pass and total depth of cut. It is essential to investigate how different geometrical designs and machining parameters can influence energy consumption in milling operations, and seek potential ways to minimize it