Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 153-162).

Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (leaves 100-106).

Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (leaves 112-118).

Thesis (Ph. D.)--University of Washington, 1996. / Vita. Includes bibliographical references (leaves [111]-119).

No description available.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2009. / The input orientation of the excavators in use today usually comprises two joysticks that control the actuator links individually. In order to perform an excavation task, several different combinations of joystick inputs are required, placing high psychomotor demands on the operator. In training an operator this creates a steep learning curve, with a lengthy training time and a reasonable amount of experience being required to perform an excavation task skilfully. In this master’s thesis a haptic1 device was developed, resolving input ergonomics and creating a single input device capable of providing feedback to the operator. The design and construction of the haptic device, with the related control scheme, is presented and discussed. The control scheme combines position and rate control, and relates all the actuator joint positions to a single end-effector point. The control and ergonomic aspects of the haptic device were tested and compared to the traditional two joystick control setup by means of the implementation of a virtual excavator simulator. The simulation was developed in MATLAB, and virtual excavator displayed in an openGL window. The objective of this study was to evaluate the human factors related to the input orientation. Ten inexperienced test subjects were recruited to perform four sets of tests, where each test required a different level of operator skill. The results indicated that, on average, the test subjects had an increased level of performance after training on the haptic device. These results strongly support the hypothesis that haptic control simplifies the operational tasks required for operating an excavator. 1The word haptic means of, or relating to, the sense of touch, or tactile

Interaction with mobile devices suffers from a number of shortcomings, most of which are linked to the small size of screens. Artificial tactile feedback promises to be particularly well suited to the mobile interaction context. To be practical, tactile transducers for mobile devices must be small and light, and yet be capable of displaying a rich set of expressive stimuli. This thesis introduces a tactile transducer for mobile interaction that is capable of distributed skin stimulation on the fingertip. The transducer works on a principle that was first investigated because of its potential application to the display of Braille. A preliminary study was conducted on an earlier version of the transducer. It concluded that subjects were able to identify simple Braille characters with a high rate of success. Then, a complete re-design of the transducer addressed the goal of integration in a handheld prototype for mobile interaction. The resulting device comprises a liquid crystal graphic display co-located with the miniature, low-power, distributed tactile transducer. Next, it was needed to measure the perceptual differences between the stimuli that the device could display. Our experiences with one evaluation approach raised questions relating to the methodology for data collection. Therefore, an analysis of the process was carried out using a stimulus set obtained with the device. By means of multidimensional scaling analysis, both the perceptual parameters forming the stimuli space and the evaluation technique were validated. Finally, two experiments were carried out with the objective to develop new mobile interactions paradigms that combined visual and tactile feedback. Both experiments modeled a list scrolling task on the device. The first experiment found a marginal improvement in performance when tactile feedback was employed. It also came at a higher attentional cost dedicated to operating the device. For the second experiment, the scrolling paradigm and the tactile feedback were improved. This lead to a decrease in the reliance on vision when tactile feedback was enabled. Results showed a 28% decrease in the number of key presses that controlled the visibility state of the scroll list.

A generally accepted goal in orthopaedic surgery today is to maximize conservation of tissue and reduce tissue damage. Bone-conserving implants have bone-mating surfaces that reproduce the natural curvature of bone structures, requiring less bone removal. No small, reliable, inexpensive and universal bone sculpting technique currently exists, however, that can both create and accurately align such complex surfaces. The goal of this thesis was to develop a haptic hard surface emulation mechanism that could be applied to curvilinear bone sculpting using a surgical robot. A novel dynamic physical constraint concept was developed that is able to emulate realistic hard constraints, smooth surface following, and realistic surface rigidity, while allowing complete freedom of motion away from the constraints. The concept was verified through the construction of a two-link manipulator prototype. Tests were run on nine users that involved each user tracing out five different virtual surfaces on a drawing surface using the prototype. The primary purposes of prototype testing were to obtain subjective data on how effectively the dynamic physical constraint concept simulates simple surfaces, to assess how it reacts to typical user interactions and to identify any unexpected behaviour. Users were 100% satisfied with the prototype’s ability to emulate realistic and stiff hard surfaces and with its ease of manipulation. The amount of incursion into each of the virtual surfaces by all the users was measured to assess the precision of the system with the goal of deciding whether this new haptic concept should be further developed specifically for precision applications such as surgery. For curvilinear surfaces, 90% of the cumulative distribution of the measured data was less than 2mm, while for linear surfaces it was less than 6mm. Four behavioural effects were noticed: lateral deflection, reverse ‘stickiness’, hysteresis and instability in certain areas. These effects were studied in detail to determine how to either eliminate them or to minimize them through system design optimization. A computer simulation was also used to model the behaviour of the prototype and to gain further understanding of these effects. These analyses showed that the concept can be successfully used in curvilinear bone sculpting.

In this dissertation, we propose a universal motion-based control framework that supports general functionalities on 2D and 3D user interfaces with a single integrated design. We develop a hybrid framework of optical and inertial sensing technologies to track 6-DOF (degrees of freedom) motion of a handheld device, which includes the explicit 6-DOF (position and orientation in the global coordinates) and the implicit 6-DOF (acceleration and angular speed in the device-wise coordinates). Motion recognition is another key function of the universal motion-based control and contains two parts: motion gesture recognition and air-handwriting recognition. The interaction technique of each task is carefully designed to follow a consistent mental model and ensure the usability. The universal motion-based control achieves seamless integration of 2D and 3D interactions, motion gestures, and air-handwriting. Motion recognition by itself is a challenging problem. For motion gesture recognition, we propose a normalization procedure to effectively address the large in-class motion variations among users. The main contribution is the investigation of the relative effectiveness of various feature dimensions (of tracking signals) for motion gesture recognition in both user-dependent and user-independent cases. For air-handwriting recognition, we first develop a strategy to model air-handwriting with basic elements of characters and ligatures. Then, we build word-based and letter-based decoding word networks for air-handwriting recognition. Moreover, we investigate the detection and recognition of air-fingerwriting as an extension to air-handwriting. To complete the evaluation of air-handwriting, we conduct usability study to support that air-handwriting is suitable for text input on a motion-based user interface.

Current robot manipulation and control paradigms have largely been developed for static or highly structured environments such as those common in factories. For most techniques in robot trajectory generation, such as heuristic-based geometric planning, this has led to putting a high cost on contact with the world. This approach and methodology can be prohibitive to robots operating in many unmodeled and dynamic environments. This dissertation presents work on using haptic based feedback (torque and tactile sensing) to formulate a controller for robot manipulation in clutter. We define “clutter” as any environment in which we expect the robot to make both incidental and purposeful contact while maneuvering and manipulating. The controllers developed in this dissertation take the form of single or multi-time step Model Predictive Control (a form of optimal control which incorporates feedback) which attempts to regulate contact forces at multiple locations on a robot arm while reaching to a goal. The results and conclusions in this dissertation are based on extensive testing in simulation (tens of thousands of trials) and testing in realistic scenarios with real robots incorporating tactile sensing. The approach is novel in the sense that it allows contact and explicitly incorporate the contact and predictive model of the robot arm in calculating control effort at every time step. The expected broader impact of this research is progress towards a new foundation of reactive feedback controllers that will include a higher likelihood of success in many constrained and dynamic scenarios such as reaching into containers without line of sight, maneuvering in cluttered search and rescue situations or working with unpredictable human co-workers.