Contactless Haptic Display Through Magnetic Field Control

Haptic rendering enables people to touch, perceive, and manipulate virtual objects in a virtual environment. Using six cascaded identical hollow disk electromagnets and a small permanent magnet attached to an operator's finger, this paper proposes and develops an untethered haptic interface through magnetic field control. The concentric hole inside the six cascaded electromagnets provides the workspace, where the 3D position of the permanent magnet is tracked with a Microsoft Kinect sensor. The driving currents of six cascaded electromagnets are calculated in real-time for generating the desired magnetic force. Offline data from an FEA (finite element analysis) based simulation, determines the relationship between the magnetic force, the driving currents, and the position of the permanent magnet. A set of experiments including the virtual object recognition experiment, the virtual surface identification experiment, and the user perception evaluation experiment were conducted to demonstrate the proposed system, where Microsoft HoloLens holographic glasses are used for visual rendering. The proposed magnetic haptic display leads to an untethered and non-contact interface for natural haptic rendering applications, which overcomes the constraints of mechanical linkages in tool-based traditional haptic devices

The feasibility of using virtual prototyping technologies for product evaluation

With the continuous development in computer and communications technology the use of computer aided design in design processes is becoming more commonplace. A wide range of virtual prototyping technologies are currently in development, some of which are commercially viable for use within a product design process. These virtual prototyping technologies range from graphics tablets to haptic devices. With the compression of design cycles the feasibility of using these technologies for product evaluation is becoming an ever more important consideration. This thesis begins by presenting the findings of a comprehensive literature review defining product design with a focus on product evaluation and a discussion of current virtual prototyping technologies. From the literature review it was clear that user involvement in the product evaluation process is critical. The literature review was followed by a series of interconnected studies starting with an investigation into design consultancies' access and use of prototyping technologies and their evaluation methods. Although design consultancies are already using photo-realistic renderings, animations and sometimes 3600 view CAD models for their virtual product evaluations, current virtual prototyping hardware and software is often unsatisfactory for their needs. Some emergent technologies such as haptic interfaces are currently not commonly used in industry. This study was followed by an investigation into users' psychological acceptance and physiological discomfort when using a variety of virtual prototyping tools for product evaluation compared with using physical prototypes, ranging from on-screen photo-realistic renderings to 3D 3600 view models developed using a range of design software. The third study then went on to explore the feasibility of using these virtual prototyping tools and the effect on product preference when compared to using physical prototypes. The forth study looked at the designer's requirements for current and future virtual prototyping tools, design tools and evaluation methods. In the final chapters of the thesis the relative strengths and weaknesses of these technologies were re-evaluated and a definitive set of user requirements based on the documentary evidence of the previous studies was produced. This was followed by the development of a speculative series of scenarios for the next generation of virtual prototyping technologies ranging from improvements to existing technologies through to blue sky concepts. These scenarios were then evaluated by designers and consumers to produce documentary evidence and recommendations for preferred and suitable combinations of virtual prototyping technologies. Such hardware and software will require a user interface that is intuitive, simple, easy to use and suitable for both the designers who create the virtual prototypes and the consumers who evaluate them

Three dimensional touch and vision for the micro-world

The ability to observe at tiny length scales has enabled key advances across the physical and life sciences. Much of what we know about the structure of cells and tissues comes from experiments on the micron length scale, enabled by new microscopy techniques. Modern manufacturing is increasingly concerned with materials that are structured on the nanometre scale, and devices which have ever-smaller features. Manipulating and measuring microscopic objects is a problem common to fields as diverse as microfabrication and cell biology, and it is these challenges that my doctoral studies have addressed. Tiny sizes mean tiny forces; so small that the light from a laser can be used to propel objects. Optical tweezers, a technique pioneered some two and a half decades ago, exploit light’s momentum to trap and manipulate objects. Now an established tool, single particles can be trapped and tracked to measure forces on a molecular scale, and this work is responsible for much of our current knowledge of motor proteins. This thesis describes advances in the holographic technology used to control multiple optical traps (and hence many trapped particles), and improved methods for monitoring the positions and forces involved. The speed with which multiple holographic optical traps can be moved has traditionally been limited by the time taken to calculate holograms, but by using consumer graphics cards and high speed Spatial Light Modulators (SLMs) I have implemented holographic systems fast enough to react to the Brownian motion of trapped particles. Brownian motion can, to some extent, be suppressed by this approach, and it also allows the trap's stiffness to be engineered to balance sensitivity against tight constraint of position. Feedback control using an SLM, rather than the other beam steering technologies that have been employed, is able to react to motion in three dimensions. This requires 3D position measurement, which is provided by the stereo microscopy technique described in Chapter 2. By illuminating and viewing the sample from two different angles it is possible to reconstruct the depth of objects. This is accomplished through a single high numerical aperture microscope objective, the same lens used to focus the trapping laser. In conjunction with a fast CMOS camera, it is possible to track particles with an accuracy of 2-3nm at several thousand frames per second. This allows measurement of forces and displacements within the control loop, that can be fed back to influence the position of the optical traps. This force information can also be relayed to the operator using a force-feedback joystick as detailed in Chapter 7. Interface design is an important part of making technology accessible to scientists from other disciplines; to this end I have also developed a multi-touch tablet application to control optical tweezers. By creating simple, reliable systems and coupling them to an intuitive interface, I have endeavoured to produce developments which are of use to the non specialist as well as to experts in optical tweezers-a number of which are now available commercially (Section 8.7). These technologies form the basis of a toolkit for working with multi-part probes in optical tweezers, and they should bear fruit in the coming years as a new form of scanning-probe microscopy emerges

Mediated Physicality: Inducing Illusory Physicality of Virtual Humans via Their Interactions with Physical Objects

The term virtual human (VH) generally refers to a human-like entity comprised of computer graphics and/or physical body. In the associated research literature, a VH can be further classified as an avatar - a human-controlled VH, or an agent - a computer-controlled VH. Because of the resemblance with humans, people naturally distinguish them from non-human objects, and often treat them in ways similar to real humans. Sometimes people develop a sense of co-presence or social presence with the VH - a phenomenon that is often exploited for training simulations where the VH assumes the role of a human. Prior research associated with VHs has primarily focused on the realism of various visual traits, e.g., appearance, shape, and gestures. However, our sense of the presence of other humans is also affected by other physical sensations conveyed through nearby space or physical objects. For example, we humans can perceive the presence of other individuals via the sound or tactile sensation of approaching footsteps, or by the presence of complementary or opposing forces when carrying a physical box with another person. In my research, I exploit the fact that these sensations, when correlated with events in the shared space, affect one\u27s feeling of social/co-presence with another person. In this dissertation, I introduce novel methods for utilizing direct and indirect physical-virtual interactions with VHs to increase the sense of social/co-presence with the VHs - an approach I refer to as mediated physicality. I present results from controlled user studies, in various virtual environment settings, that support the idea that mediated physicality can increase a user\u27s sense of social/co-presence with the VH, and/or induced realistic social behavior. I discuss relationships to prior research, possible explanations for my findings, and areas for future research

Novel delivery and sample mixing for synchrotron diffraction experiments using acoustic levitation with multi-transducer arrays

Acoustic levitation may utilise standing waves at ultrasonic frequencies to manipulate suspended substances and small objects in a contactless manner. These materials may be levitated in the positions in which the nodes are located, corresponding to positions of low acoustic pressure. In recent years, off the shelf transducer based acoustic levitators have been used for contactless manipulation of liquids. These systems benefit from requiring low power and low-cost components making acoustic levitation more accessible to the masses. Such a system was investigated in this work for presenting protein crystals, within their mother liquor, to the I24 beamline at Diamond Light Source for x-ray diffraction experiments. It was found that the crystals tended to sediment toward the bottom of the droplets, which were oblate in shape. The droplets which were levitated often became unstable and fell from their suspended position, or they would not detach from the pipette tip when they were being injected. To rectify this, a coating of silicone oil was added allowing the droplets to remain stable as well as limit the evaporation of the droplet whilst it was manually inserted and the area cleared of personnel before the x-ray beam was engaged. This silicone oil coating is non-crystalline and thus did not invalidate the results collected which showed the lysozyme crystal structure with a resolution of 1.69 A, confirming acoustic levitation as a good sample presentation method for these types of experiments. To remove the requirement for the silicone oil, a bespoke system was created named the DLS-Lev that allowed top-loading of the sample. The droplets of mother liquor which contained protein crystals were easily detached from the pipette tip into the traps within the DLS-Lev system owing to the increased strength of the traps in the modified design. This system, paired with an automated pipette, facilitated sample mixing experiments whilst the x-ray beam was engaged. The further development of the pipetting system was halted due to the COVID-19 pandemic. However, future work should see the permanent installation of these systems at the I24 beamline at Diamond Light Source, as well as additional bespoke acoustic levitators designed for the other beamlines specialising in the research of protein structure via x-ray scattering techniques