Real-time Virtual Object Insertion for Moving 360° Videos

We propose an approach for real-time insertion of virtual objects into pre-recorded moving-camera 360° video. First, we reconstruct camera motion and sparse scene content via structure from motion on stitched equirectangular video. Then, to plausibly reproduce real-world lighting conditions for virtual objects, we use inverse tone mapping to recover high dynamic range environment maps which vary spatially along the camera path. We implement our approach into the Unity rendering engine for real-time virtual object insertion via differential rendering, with dynamic lighting, image-based shadowing, and user interaction. This expands the use and flexibility of 360° video for interactive computer graphics and visual effects applications

Design, optimization and flight testing of a micro air vehicle

Micro Air Vehicles (MAVs) are a new type of aircraft maturing every year. The first mission-capable MAVs are already available on the market. Similarly to larger UAVs, MAVs may be used in a variety of applications, both military and civilian, such as situational awareness, reconnaissance, data relay, air sampling etc. This study describes the development of a method for rapid design and optimization based on some basic preliminary design parameters. Low aspect ratio (LAR) wing theory and experimental data by Mueller and Torres have been used to analytically predict the performance of the MAV. This has also been validated by the author’s wind tunnel experiments, also described in this thesis. The results of the wind tunnel experiments are presented. Performance of the propulsion system (motor, propeller, battery, speed controller) was evaluated using other commercially available tools. The design optimization concerns the wing geometry under certain constraints applied by the user. The design optimization code, which is based on Genetic Algorithms, was written in MATLAB. As a conclusion to the project, a prototype was built and successfully test flown, which proved the feasibility of the developed method. A detailed description of the manufacture and testing of the prototype is also included in this thesis

Guidance, Navigation and Control of a Fly-By-Wire Transport Category Airship Designed for Hover Cargo Delivery

The purpose of this thesis is to develop fly-by-wire pilot controls for a transport category airship propelled with six thrust vectoring engines, and to develop control laws to maintain position, heading, and attitude during hover and cargo operations. Owing to the large body area, most airships require that they be pointed into the wind to maintain their position. This research aims at controlling an airship attitude and position during hover cargo delivery, irrespective of the wind direction. Control laws were developed for two primary modes of the airship: Flight (High Speed Mode) and Hover (Cargo Delivery Mode). Different sets of pilot controls were developed for each mode, oriented towards reduced pilot work load and simplicity of operation. A proof of concept sub-scale model of the airship was built and flown in an indoor hangar environment. An Attitude Heading Reference System (AHRS) system was implemented using Inertial Measuring Unit (IMU) and a Magnetometer. Indoor positioning of the airship was achieved using target LEDs, and applying robotic vision techniques such as motion detection, color blob analysis, and stereo vision. The developed control laws were tested during indoor flight tests, and conclusions were drawn regarding their feasibility

Conceptual and Preliminary Design of a Stowable Ruggedized Micro Air Vehicle

This study presents both feasibility and preliminary design studies of a ruggedized, stowable, ballistically launched Micro Air Vehicle (MAV). A vehicle capable of being stored within a 40 mm diameter, 133 mm long cylinder and able to withstand a significantly rough environment when stowed was desired. Minimum performance specifications were a 20% range increase from a 450 m range, 45° launch angle ballistic trajectory and a gliding time of 30 s from the apex of said trajectory. To this end, a study of comparable MAV systems, available control and communication electronics, low Reynolds number flight, ballistic flight, and advanced projectiles was conducted. It was found that the concept was possible using current electronics, however, these would require a large majority of the available volume necessitating the novel, compact, wing stowage systems discussed within. While aerodynamically feasible the transition between ballistic and aircraft flight will necessitate significant sensor and control logic design. The small scales of this project necessitated consideration of the vagaries of low Reynolds number flight. Despite the final design proposals maintaining chordwise Reynolds numbers greater than 100,000 several key trends were found to be significantly different than those encountered in classical aerodynamic theory; particularly the existence of an optimum aspect ratio for maximum lift to drag ratio of the wing alone. For a fixed wing area and velocity increasing the aspect ratio, thereby reducing induced drag, also reduced the chordwise Reynolds number which reduced the efficiency of the airfoil. At the optimum benefits from reducing induced drag balanced with the penalties of reduced airfoil performance. The feasibility study focused primarily on volumetric concerns; minimizing stowed wing volume was the main goal. Several design iterations were constructed in SolidWorks prior to the development of two concepts ready for prototyping and testing. Design optimization was performed with both classical semi-empirical methods using Missile DATCOM and a custom in-house Matlab code as well as the Fluent CFD package. Significant work was done to find a suite of solver settings and mesh generation parameters capable of predicting 2D and 3D low Reynolds number airfoil performance with sufficient quality for preliminary design work. Optimization studies found that achieving both initial performance goals with a single aircraft would be highly inefficient. This effort concluded with a pair of designs, one high-speed cruise-to-target version capable of 700 m range and 9 s gliding time optimized for rapid-response, and a long-endurance glider with a flight time greater than 60 s optimized for surveillance purposes

Dynamic balance and walking control of biped mechanisms

The research presented here focuses on the development of a feedback control systems for locomotion of two and three dimensional, dynamically balanced, biped mechanisms. The main areas to be discussed are: development of equations of motion for multibody systems, balancing control, walking cycle generation, and interactive computer graphics. Additional topics include: optimization, interface devices, manual control methods, and ground contact force generation;Planar (2D) and spatial (3D) multibody system models are developed in this thesis to handle all allowable ground support conditions without system reconfiguration. All models consist of lower body segments only; head and arm segments are not included. Model parameters for segment length, mass, and moments of inertia are adjustable. A ground contact foot model simulates compression compliance and allows for non-uniform surfaces. In addition to flat surfaces with variable friction coefficients, the systems can adapt to inclines and steps;Control techniques are developed that range from manual torque input to automatic control for several types of balancing, walking, and transitioning modes. Balancing mode control algorithms can deal with several types of initial conditions which include falling and jumping onto various types of surfaces. Walking control state machines allow selection of steady-state velocity, step size, and/or step frequency;The real-time interactive simulation software developed during this project allows the user to operate the biped systems within a 3D virtual environment. In addition to presenting algorithms for interactive biped locomotion control, insights can also be drawn from this work into the levels of required user effort for tasks involving systems controlled by simultaneous user inputs;Position and ground reaction force data obtained from human walking studies are compared to walking data generated by one of the more complex biped models developed for this project

Real-time Virtual Object Insertion for Moving 360° Videos

We propose an approach for real-time insertion of virtual objects into pre-recorded moving-camera 360° video. First, we reconstruct camera motion and sparse scene content via structure from motion on stitched equirectangular video. Then, to plausibly reproduce real-world lighting conditions for virtual objects, we use inverse tone mapping to recover high dynamic range environment maps which vary spatially along the camera path. We implement our approach into the Unity rendering engine for real-time virtual object insertion via differential rendering, with dynamic lighting, image-based shadowing, and user interaction. This expands the use and flexibility of 360° video for interactive computer graphics and visual effects applications

Vibrotactile Sensory Augmentation and Machine Learning Based Approaches for Balance Rehabilitation

Vestibular disorders and aging can negatively impact balance performance. Currently, the most effective approach for improving balance is exercise-based balance rehabilitation. Despite its effectiveness, balance rehabilitation does not always result in a full recovery of balance function. In this dissertation, vibrotactile sensory augmentation (SA) and machine learning (ML) were studied as approaches for further improving balance rehabilitation outcomes. Vibrotactile SA provides a form of haptic cues to complement and/or replace sensory information from the somatosensory, visual and vestibular sensory systems. Previous studies have shown that people can reduce their body sway when vibrotactile SA is provided; however, limited controlled studies have investigated the retention of balance improvements after training with SA has ceased. The primary aim of this research was to examine the effects of supervised balance rehabilitation with vibrotactile SA. Two studies were conducted among people with unilateral vestibular disorders and healthy older adults to explore the use of vibrotactile SA for therapeutic and preventative purposes, respectively. The study among people with unilateral vestibular disorders provided six weeks of supervised in-clinic balance training. The findings indicated that training with vibrotactile SA led to additional body sway reduction for balance exercises with head movements, and the improvements were retained for up to six months. Training with vibrotactile SA did not lead to significant additional improvements in the majority of the clinical outcomes except for the Activities-specific Balance Confidence scale. The study among older adults provided semi-supervised in-home balance rehabilitation training using a novel smartphone balance trainer. After completing eight weeks of balance training, participants who trained with vibrotactile SA showed significantly greater improvements in standing-related clinical outcomes, but not in gait-related clinical outcomes, compared with those who trained without SA. In addition to investigating the effects of long-term balance training with SA, we sought to study the effects of vibrotactile display design on people’s reaction times to vibrational cues. Among the various factors tested, the vibration frequency and tactor type had relatively small effects on reaction times, while stimulus location and secondary cognitive task had relatively large effects. Factors affected young and older adults’ reaction times in a similar manner, but with different magnitudes. Lastly, we explored the potential for ML to inform balance exercise progression for future applications of unsupervised balance training. We mapped body motion data measured by wearable inertial measurement units to balance assessment ratings provided by physical therapists. By training a multi-class classifier using the leave-one-participant-out cross-validation method, we found approximately 82% agreement among trained classifier and physical therapist assessments. The findings of this dissertation suggest that vibrotactile SA can be used as a rehabilitation tool to further improve a subset of clinical outcomes resulting from supervised balance rehabilitation training. Specifically, individuals who train with a SA device may have additional confidence in performing balance activities and greater postural stability, which could decrease their fear of falling and fall risk, and subsequently increase their quality of life. This research provides preliminary support for the hypothesized mechanism that SA promotes the central nervous system to reweight sensory inputs. The preliminary outcomes of this research also provide novel insights for unsupervised balance training that leverage wearable technology and ML techniques. By providing both SA and ML-based balance assessment ratings, the smart wearable device has the potential to improve individuals’ compliance and motivation for in-home balance training.PHDMechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/143901/1/baotian_1.pd

3D Printing Technologies

The family of technologies collectively known as additive manufacturing (AM) technologies, and often called 3D-printing technologies, is rapidly revolutionizing industrial production. AM’s potential to produce intricate and customized parts starting from a digital 3D model makes it one of the main pillars for the forthcoming Industry 4.0. Thanks to its advantages over traditional manufacturing methodologies, AM finds potential applicability in virtually all production fields. As a natural consequence of this, research in this field is primarily focused on the development of novel materials and techniques for 3D printing. This Special Issue of Technologies, titled “3D Printing Technologies”, aims at promoting the latest knowledge in materials, processes, and applications for AM. It is composed of six contributions, authored by influential scientists in the field of advanced 3D printing. The intended audience includes professors, graduate students, researchers, engineers and specialists working in the field of AM

Design and development of a controllable wing loading unmanned aerial system

Vertical takeoff and landing (VTOL) unmanned aerial systems (UAS) offer all the benefits of wing borne flight without the need for conventional takeoff and landing (CTOL) infrastructure. There exists many effective VTOL UAS that utilize battery-powered rotors to provide vertical thrust. The problem with the existing UAS is that the VTOL capability is achieved at the sacrifice of speed, fuel/payload, and operational flexibility. Also, many of these UAS must transition from hover to horizontal flight which is both complex and risky.The current research explores a new type of point launch and landing system that utilizes only liquid fuels, i.e. no electric powered rotors. Instead of exposed rotors, the new configuration has a turbojet engine mounted vertically inside the fuselage to provide vertical thrust. With the turbojet being 'hidden' from the freestream air, it mitigates the drag seen from the other configurations' rotors, allowing a higher top speed. Also, the new configuration bypasses the hover and transition phases of flight.The vertical turbojet effectively changes the weight of the aircraft which allows it to have controllable wing loading (CWL), and therefore variable stall speed. With the jet at full power, the aircraft weighs virtually nothing and can takeoff from the launchpad with almost no airspeed. Likewise, on landing, the aircraft can slow to almost zero airspeed and land with little to no rollout. The CWL configuration has proved it possible to have approximately a 95% reduction in landing distance.This paper describes the study, design, manufacturing, and testing of the point launch and landing CWL configuration. Two commercial off the shelf (COTS) UAVs were retrofitted with a CWL system to test the validity of the idea and the necessary systems.Following the proof of the idea, a composite UAS with a maximum takeoff weight of 50 lb. was designed, manufactured, and flown. It successfully demonstrated both a point launch and point landing while being capable of reaching speeds of up to 100 mph, more than double the top speed of some other VTOL UAS in its weight class