P.V.M. Rao

Indian Institute of Technology Delhi | IIT Delhi · Department of Mechanical Engineering

Geometry plays a crucial role in fostering spatial understanding and problem-solving skills, essential for both academic excellence and real-world applications. However, students with visual impairments (VI) face challenges due to the limited availability of inclusive tools and resources for geometry. This results in a deficiency in effective learn...

Tactile diagrams are embossed diagrams on a sheet that visually challenged people explore through touch. One of the common processes to prepare these diagrams is by vacuum thermoforming. These diagrams help non-sighted people to explore pictorial contents such as maps, books, charts, and artworks. The identification of suitable and affordable polym...

People with visual impairments in India have low literacy rates and only a few pursue higher education at the country's top universities. We present an insight into the educational experiences of these few university students with visual impairment based on the Frame of Interdependence. We found that educational challenges arise when interdependenc...

Two-dimensional pin array tactile displays enable access to tactile graphics that are important for the education of students with visual impairments. Due to their prohibitive cost, limited access, and limited research within HCI, the rules to design graphical primitives on these low-resolution tactile displays are unclear. In this paper, eight tac...

Before visiting a new location, we often look at maps to build an a priori mental representation of the environment using landmarks and points of interest. No such options are easily available for persons with visual impairment (PVIs). As a result, PVIs are often dependent on others for assistance with any activities that require visiting unfamilia...

The present invention provides a system and a method for analysing embossed surfaces of a sheets. The method determining at least one of a plurality for parameters when a user is performing exploration activity on the embossed surfaces of the sheet, wherein the plurality of parameters includes coordinates of at least one hand of the user, at least...

Globally, it has been estimated that approximately 1.3 billion people live with some form of vision impairment. Out of these, around 91 million people are in South-East Asia [13]. Most people with vision impairment (PVI) are over the age of 50 years, and in fast-growing economies like India and China, a certain demographic shift would mean a signif...

Traditional tactile diagrams for the visually-impaired (VI) use short Braille keys and annotations to provide additional information in separate Braille legend pages. Frequent navigation between the tactile diagram and the annex pages during the diagram exploration results in low efficiency in diagram comprehension. We present the design of FingerT...

The purpose of this research was to investigate clothing needs of young Indian male motorcycle riders. Protective, comfort and aesthetic characteristics of motorcycle clothing were assessed through selected movement analysis and survey. Data was collected from 50 motorcycle riders (mean age 27.7 years, mean weight 70.4 kgs) from 4 metropolitan citi...

Mobility and Education are primary concern for socioeconomic inclusion of the visually impaired (VI). Indoor mobility is challenging for VI because of increasing structural complexity, unavailabil-ity of open standards for indoor navigation and lack of orientation and mobility training. Very often adoption of new technology including security conce...

Purpose Whilst motorcycling is an activity of pleasure in most parts of the world, in India, it is a regular mode of commuting. The number of registered motorized two wheelers increased at the rate of 14.7 percent during the year 2016-2017 to reach the figure of 20.19m in 2018. But, with this increase, the number of motorcycle road accidents is als...

Background

Continuous need to increase productivity and reliability in machining has led to high-performance machines that are often characterized by high energy demands. As a result, energy minimization is identified as one of the key goals in machining. With the availability of improved predictive models for energy estimation in machining, energy-conscious...

Micro-milling has shown great potential in producing complex miniaturized components over wide range of materials. It can also fabricate micro-products in small batches efficiently and economically. In spite of these advantages, several challenges hinder its ability to produce components with better dimensional accuracy. Among several factors, tool...

This paper is based on work from the Global Research, Innovation, and Education on Assistive Technology (GREAT) Summit that was coordinated by WHO’s Global Cooperation on Assistive Technology (GATE). The purpose of this paper is to describe the needs and opportunities embedded in the assistive product lifecycle as well as issues relating to the var...

With the growing concern for environmental sustainability, it is necessary to address the environmental damages caused by our present consumption approach. The packaging of products is one of the contributors to environmental damages, as these product packages often pose harm to the environment during production, use and when discarded. Most of the...

Effective design of tactile graphics in education of the blind and visually impaired has long been debated by researchers, particularly whether pictorial sources are required. This work demonstrates that users of tactile graphics recognize distinctive abstract features (as the authors call them, "basic identity tags" or BITs), to differentiate, ide...

Purpose The purpose of this paper is to investigate and propose a framework for environmental impact assessment of packaging material being used to package a product. Design/methodology/approach The research considers parameters identified in the literature by the use of “Delphi Technique.” Based on available data, methods of measurement of the...

The present research work was concerned with the development of an improved predictive model for energy estimation in the machining process. The need for a comprehensive predictive model which can account for generic cutting conditions together with all machine tool related factors was felt and has been attempted here. The proposed model was able t...

This work systematically reviews the assistive technology solutions for pedestrians with visual impairment and reveals that most of the existing solutions address a specific part of the travel problem. Technology-centered approach with limited focus on the user needs is one of the major concerns in the design of most of the systems. State-of-the-ar...

Linear guides are extensively employed in several industrial applications. Miniaturization, minimal friction, cost efficiency and low maintenance are the major challenges faced while developing a linear motion system. This paper presents design and realization of such systems, overcoming the aforementioned challenges. Linear guidance mechanisms, su...

Refreshable Braille Display (RBD) is a device that enables people with blindness to access digital textual content through tactile interface. The use of commercially available RBDs is restricted to affluent individuals and organizations due to their high cost, which restricts their penetration in developing nations. Braille displays based on shape...

Micro-end milling is used for manufacturing of complex miniaturized components precisely in wide range of materials. It is important to predict cutting forces accurately as it plays vital role in controlling tool and workpiece deflections as well as tool wear and breakage. The present study attempts to incorporate process characteristics such as ed...

In this information-driven era, the use of pictorial forms of communication has become widely popular, making the world increasingly inaccessible to visually impaired and blind individuals. Accessing print media has also been a challenge for this population. Braille, a standard writing system for perception through touch, and audio translations of...

A process geometry model determines engagement angle and instantaneous uncut chip thickness which forms basis in predicting cutting forces and surface quality in micro-end milling operation. This paper presents a process geometry model incorporating cutter runout, elastic recovery of work material and minimum chip thickness. These characteristics a...

A process geometry model determines engagement angle and instantaneous uncut chip thickness which forms basis in predicting cutting forces and surface quality in micro-end milling operation. This paper presents a process geometry model incorporating cutter runout, elastic recovery of work material and minimum chip thickness. These characteristics a...

End milling of the curved surfaces is characterized by significant amount of engagement variation along the tool path which results in deflection-induced surface error on the machined components. Feed rate regulation cannot be used in this case to minimize the surface errors as it necessitates continuous change in feed rate along the tool path whic...

For many decades machine tools have been designed based on engineering judgment and past experience of the designers and hence in many cases are found to be quite bulky for the intended requirements. With the increase in competition, machine tool manufacturers are forced to deliver machine tools with high precision but light in weight. This is prom...

Persons with blindness access computers with the help of refreshable Braille displays and speech synthesis softwares. Braille has distinguished advantages over synthetic speech, especially because of its important role in uplifting education, employment and income. However, commercially available Braille displays are typically priced in the range o...

Lean concepts are routinely used in manufacturing but are still relatively new to New Product Development (NPD) process. If manufacturing can be modeled as flow of material, an analogous model for NPD process would be flow of information. This paper addresses the issue of eliminating wastes in new product development process by bringing lean concep...

Cutter deflections induce significant amount of surface error on machined components and it is one of the major obstacles towards achieving higher productivity in peripheral milling operation. These surface errors do not take one particular form and their shape and profile measured along axial direction, varies significantly with cutting conditions...

Partial or complete visual impairment, congenital or adventitious, hampers an individual’s visual stimuli perception ability. For reading, the visually impaired primarily rely on Braille, a script read through touch. Its 6-dot and 8-dot configurations have been adapted for use with different languages, making it popular around the globe. However, r...

Purpose The purpose of this paper is to report experimental investigations performed to analyze the effect of process parameters on the shape accuracy of selective laser sintered (SLS) parts. Design/methodology/approach The effect of process parameters, namely build orientation, laser power, scan speed, cylinder diameter and build chamber temperat...

There are many machining situations where slender tools are used to machine thin walled tubular workpieces. Such instances are more common in machining of aircraft structural parts. In these cases, cutting force induced tool as well as workpiece deflections are quite common which result into surface error on machined components. This paper presents...

Machining of thin-walled tubular geometries poses interesting problems from a process planning perspective. In machining of such geometries by milling, cutting force-induced tool and workpiece deflections have to be overcome in order to realize part accuracies without compromising productivity. This calls for a systematic study of surface errors on...

This article presents a novel approach for tailoring material properties in parts fabricated using layered manufacturing (LM). Solid model of the part is subdivided into various subparts based on stress analysis. All subdivided solid models are fabricated together by using selective laser sintering (SLS) process with parameters assigned as per thei...

The bus transport system is seldom tuned to the special needs of the visually challenged. Identification of buses arriving at bus stops is difficult because route numbers are only displayed on the number plate. Moreover, a number of buses arrive together and line up arbitrarily at bus stops. Even after identification, it is difficult to navigate to...

Prediction of cutting forces and machined surface error in peripheral milling of curved geometries is non-trivial due to varying workpiece curvature along tool path. The complexity in this case, arises due to continuously changing process geometry as workpiece curvature varies along tool path. In the presence of cutter runout, the situation is furt...

The present work is concerned with automated generation of process plans for CMM based part inspection from CAD models. The importance and advantage of the proposed system is that it uses STEP (ISO 10303) file of the part to be inspected as an input and gives inspection process plan of the part as an output in DMIS (ISO 22903) format. This is the f...

Shrinkage in selective laser sintering process is primarily influenced by material, process parameters and the geometry of the fabricated part. The part inaccuracy due to this shrinkage is overcome by calibrating and compensating it. Further improvements in accuracy of the part can be achieved by conducting more studies to appreciate the nature of...

This paper presents a new model for shrinkage and a new approach for shrinkage compensation to enhance the accuracy of parts produced by selective laser sintering (SLS)–a solid freeform fabrication process. The present prevailing approach as proposed by machine manufacturers is simple but not accurate. A new shrinkage model which accounts for part...

Parting-direction selection for die-casting parts is an important decision, which affects further downstream activities like manufacturing. Selecting a suitable parting direction in die-casting is difficult as it is influenced by many factors based on shape, topology and manufacturing process. Normally it is decided by die-casting experts. There is...

A dynamic modeling of multibody systems having spherical joints is reported in this work. In general, three intersecting orthogonal revolute joints are substituted for a spherical joint with vanishing lengths of intermediate links between the revolute joints. This procedure increases sizes of associated matrices in the equations of motion, thus inc...

An experimental investigation has been carried out to study the feasibility of processing blended powder of polyamide (PA) and organically modified nanoclay using selective laser sintering. The effect of nanoclay on the sintering parameters and mechanical properties of the sintered specimen have been studied. This article presents the details of pr...

In this paper, the combined kinematic and sensitivity optimization of a rack-and-pinion steering linkage is performed. This steering linkage is the most common steering system used in passenger cars. Although, the steering linkage has received a lot of attention for the minimization of the steering errors, no attempt has been made so far to investi...

Lean Machine Tool is the one which meets all customer’s requirements, just enough without being equipped with any unnecessary features or accessories. In acquiring a new machine tool it is neither easy nor straightforward to decide if a given accessory is desirable or not. Addition of any accessory would affect product cost, performance, reliabilit...

This paper presents new approach for shrinkage compensation in selective laser sintering (SLS) process to improve the accuracy of parts produced. Shrinkage is compensated along single direction dexel space generated from the part geometry. The scaling factor used in this compensation is calculated from shrinkage model (It is the empirical relation...

Selective laser sintering (SLS) is a powder-based rapid prototyping process in which parts are built by sintering of selected areas of layers of powder using laser. Nowadays, SLS is emerging as a rapid manufacturing technique, which produces functional parts in small batches, particularly in aerospace application and rapid tooling. Therefore, SLS p...

Selective laser sintering (SLS) is one of the most popular layered manufacturing processes used for making functional prototypes of polymers and metals. It is a powder-based process in which layers of powder are spread and laser is used to sinter selected areas of preheated powder. In the present work, experimental investigations have been made to...

The present paper investigates the effect of two variables, namely direction of parameterization and cutter diameter on process geometry, cutting forces, and surface error in peripheral milling of curved geometries. In machining of curved geometries where the curvature varies continuously along tool path, the process geometry variables, namely feed...

Direct integration of reverse engineering and rapid prototyping removes two intermediate steps of surface fitting from point cloud data and STL file generation from CAD models. Therefore errors introduced due to surface fitting and triangulations are eliminated and also the process of STL data validation and repair is avoided. Intermediate point ba...

In this paper, numerical slicing of parametric B-Rep solids has been proposed based on the concepts of virtual cloud points and Delaunay triangulation for the purpose of layered manufacturing. The layer geometry thus obtained readily lent itself to application of an optimum hatching algorithm that minimises the build time. The problem has been trea...

Early cost estimate of a part is important information and forms a basis for preparing quotations, which are competitive from a market point of view. It is seen that a commonly adopted approach of variant cost estimation based only on geometric information of the component is not always accurate. This is also true in the case of die-cast parts. The...

Determining parting direction and parting line for die-cast parts is a nontrivial task that not only depends upon shape and topology of the part, but also on many process related factors. Normally, a die-casting expert decides parting direction and parting line, intuitively taking into account a large number of factors, and this process can be time...

This paper deals with design and process planning issues for improving part accuracy in Selective Laser Sintering (SLS) process. SLS, earlier used for prototyping purposes, is now fully capable of producing functional components and rapid tools with the development of metallic prototypes or metal and polymer blends. SLS process involves heat transf...

Shape matching finds application in many areas like character recognition, object search, object tracking, computer games, mechanical part inspection etc. This paper presents a new approach to shape matching of free-form surfaces using an analogy from structural mechanics. In this methodology, one of the two surfaces being matched is treated as an...

Automated manufacturability analysis is an important tool with the designer which is meant to incorporate manufacturability aspects at initial stages of design. This paper deals with a system developed for automated manufacturability analysis for die-cast parts. Purpose of this system is to assist designers in their effort to come up with manufactu...

In this paper, a recursive algorithm for a general closed-loop system is applied for the dynamic model of a rack and pinion steering (RPS) linkage. It is useful to find the actuating torques at the pinion as desired in the steer-by-wire (SBW) systems, and to compute the constraint forces which can be used for the design of the links of the mechanis...

There are numerous constraints that visually challenged people face in independent mobility and navigation. They primarily use the white cane as a mobility aid allowing them to detect close by obstacles on the ground. The detection of objects above knee height is almost impossible and is a major hindrance for them. In this work, we have reported th...

Gears, bearings, springs, fasteners etc. are some typical machine elements used to build machines and mechanical systems. These elements are used for performing one or more of functions such as, to transmit motion, to support moving members, to store energy, to join two components etc. The continuous miniaturization and the need for mechanical syst...

Rapid Prototyping (RP) is two decade old technology to quickly produce tangible objects directly from a 3D CAD model and is being used to shorten and simplify the product development cycle for many applications including aerospace, automobile and home appliances etc., It involves adding material successively, in layers, to create a solid of a prede...

This paper presents compensation of surface error due to cutting force-induced tool deflections in a peripheral milling process. Previous research attempts on this topic deal with error compensation in machining of straight geometries only. This paper is concerned with peripheral milling of variable curvature geometries where the workpiece curvatur...

This paper investigates cutting forces and surface error due to cutting force-induced tool deflections in peripheral milling of curved geometries. In machining workpiece geometries, where curvature varies continuously along the tool path, both cutting force and surface error vary from point to point. This is different from the case of machining str...

In this paper, dynamic model of a class of parallel systems, namely, the hexaslides, is proposed. The model developed is based on the concept the decoupled natural orthogonal complement (DeNOC) matrices, introduced elsewhere. The dynamic model of hexslides, though complex due to the existence of multi-loop kinematic chains, is required for actuator...

In today’s manufacturing scenario, accounting for manufacturability considerations at the product design stage is not an option but a necessity. When CAD/CAM tools are used to reduce design lead times, accounting for manufacturing process related considerations implicitly is often difficult. Availability of manufacturability advisor systems that an...

Shape matching has many application areas which include manufactured part inspection. This paper deals with shape matching of planar and spatial curves based on the concept of deformation energy. We combine the concepts of differential geometry, geometric modeling, mechanics of deformable bodies and computer aided part inspection to propose a metho...

Automated manufacturability evaluation of a given design is a key requirement in realizing complete integration of design and process planning. It would still be better to control the designing process itself with manufacturability information. The purpose of such an evaluation is to assist designers in their effort to come up with manufacturable p...

The paper presents the dimensional design of a class of parallel manipulators, namely, Hexaslides. The design of hexaslides is formulated as a multiobjective optimization problem considering workspace and dexterity as dual objectives. As the relative emphasis on workspace and dexterity varies depending on the application, a set of Pareto-optimal so...

Dodekapod is a recent development in the area of parallel manipulators. It is a manipulator with 12 degree of freedom proposed as an alternative to six degree of freedom Hexapod, to overcome workspace limitations. This paper deals with the inverse and forward kinematics of Dodekapod. A hierarchical method to solve the kinematics is proposed assumin...

The paper presents modelling of tooth trajectory and process geometry in peripheral milling of curved surfaces. The paper differs from previous work in this area, in two respects. Firstly it deals with milling of variable curvature geometries unlike zero and constant curvature geometries dealt in the past. Secondly true tooth trajectories are consi...

This paper presents stiffness analysis of hexaslides, a class of parallel manipulators with six constant length legs, the base joints of which move along six distinct rail-axes. In the design of hexaslides for machine tool applications, stiffness as well as its variation within the workspace is important. The stiffness of any parallel kinematic mac...

Gears, Bearings, Springs, Fasteners etc. are some of the typical machine elements used to build machines and mechanical systems. The function of these machine elements is to transmit motion, to support moving members, to store energy, to join two components etc. Carbon nanotubes can be used as these machine elements when building nano-machines or n...

Estimating the shape and size of a scanning tunneling microscope (STM) tip before scanning is often necessary for the correct interpretation of the STM data. This is particularly essential when using the STM as a metrology tool. It is common among researchers to idealize the tip shape as conical, spherical, or parabolic. By using a field ion micros...

Automated manufacturability assessment of a given design is a key requirement in realizing complete integration of design (CAD) and manufacturing (CAM). The paper deals with a system developed for automated manufacturability assessment by machining processes. The purpose of this system is to assist designers in their effort to come up with manufact...

Realizing design–process planning integration is vital to the competitiveness of manufacturing organization and its ability to respond rapidly to market changes. Many attempts have been made in the past proposing the integration of the two activities based on product data models. However, both design and process planning activities are knowledge in...

Solid modeling involves creation and manipulation of complete and unambiguous mathematical representations of 3-D objects. The purpose of such a representation is to provide tools for visualization, calculation of geometric properties and realization by design and manufacturing processes. Existing methods of solid modeling namely constructive solid...

Modeling is to specify, visualize and document models of application systems including their structure before actual implementation. This paper attempts a system level modeling for sheet metal process planning for integration purposes. Many attempts have been made in the past proposing sheet metal process planning systems at implementation level ba...

This paper presents kinematic analysis of a class of parallel manipulators, namely, Hexaslides, for machine tool applications. Hexaslides have constant-length legs. The inverse and direct kinematics solutions, to study the workspace properties of hexaslides are presented. Various kinematic performance indices, namely, workspace volume, workspace vo...

All sheet-forming processes suffer from a limitation that tooling in the form of molds/dies is a precursor for realizing any simple or complex shape. In order to overcome this limitation, discrete surface tooling has been proposed in the past. This consists of a large number of closely spaced surface tool elements arranged in a matrix form whose he...