It remains unquestionable that space-based technology is an indispensable component of modern daily lives. Success or failure of space missions is largely contingent upon the complex system analysis and design methodologies exerted in converting the initial idea

into an elaborate functioning enterprise. It is for this reason that this dissertation seeks to contribute towards the search for simpler, efficacious and more reliable methodologies and tools that accurately model and analyze space systems dynamics. Inopportunely, despite the inimical physical hazards, space systems must endure a perturbing dynamical environment that persistently disorients spacecraft attitude, dislodges spacecraft from their designated orbital locations and compels spacecraft to follow undesired orbital trajectories. The ensuing dynamics’ analytical models are complexly structured, consisting of parametrically excited nonlinear systems with external periodic excitations–whose analysis and control is not a trivial task. Therefore, this dissertation’s objective is to overcome the limitations of traditional approaches (averaging and perturbation, linearization) commonly used to analyze and control such dynamics; and, further obtain more accurate closed-form analytical solutions in a lucid and broadly applicable manner. This dissertation hence implements a multi-faceted methodology that relies on Floquet theory, invariant center manifold reduction and normal forms simplification. At the heart of this approach is an intuitive system state augmentation technique that transforms non-autonomous nonlinear systems into autonomous ones. Two fitting representative types of space systems dynamics are investigated; i) attitude motion of a gravity gradient stabilized spacecraft in an eccentric orbit, ii) spacecraft motion in the vicinity of irregularly shaped small bodies. This investigation demonstrates how to analyze the motion stability, chaos, periodicity and resonance. Further, versal deformation of the normal forms scrutinizes the bifurcation behavior of the gravity gradient stabilized attitude motion. Control laws developed on transformed, more tractable analytical models show that; unlike linear control laws, nonlinear control strategies such as sliding mode control and bifurcation control stabilize the intricate, unwieldy astrodynamics. The pitch attitude dynamics are stabilized; and, a regular periodic orbit realized in the vicinity of small irregularly shaped bodies. Importantly, the outcomes obtained are unconventionally realized as closed-form analytical solutions obtained via the comprehensive approach introduced by this dissertation.

The mean age of the world’s population is rapidly increasing and with that growth in an aging population a large number of elderly people are in need of walking assistance. In addition, a number of medical conditions contribute to gait disorders that require gait rehabilitation. Wearable robotics can be used to improve functional outcomes in the gait rehabilitation process. The ankle push-off phase of an individual’s gait is vital to their ability to walk and propel themselves forward. During the ankle push-off phase of walking, plantar flexors are required to providing a large amount of force to power the heel off the ground.

The purpose of this project is to improve upon the passive ankle foot orthosis originally designed in the ASU’s Robotics and Intelligent Systems Laboratory (RISE Lab). This device utilizes springs positioned parallel to the user’s Achilles tendon which store energy to be released during the push off phase of the user’s gait cycle. Goals of the project are to improve the speed and reliability of the ratchet and pawl mechanism, design the device to fit a wider range of shoe sizes, and reduce the overall mass and size of the device. The resulting system is semi-passive and only utilizes a single solenoid to unlock the ratcheting mechanism when the spring’s potential force is required. The device created also utilizes constant force springs rather than traditional linear springs which allows for a more predictable level of force. A healthy user tested the device on a treadmill and surface electromyography (sEMG) sensors were placed on the user’s plantar flexor muscles to monitor potential reductions in muscular activity resulting from the assistance provided by the AFO device. The data demonstrates the robotic shoe was able to assist during the heel-off stage and reduced activation in the plantar flexor muscles was evident from the EMG data collected. As this is an ongoing research project, this thesis will also recommend possible design upgrades and changes to be made to the device in the future. These upgrades include utilizing a carbon fiber or lightweight plastic frame such as many of the traditional ankle foot-orthosis sold today and introducing a system to regulate the amount of spring force applied as a function of the force required at specific times of the heel off gait phase.

The sense of sight is arguably the most common method that our body uses for gathering data of the world around us. However, that primary tool is negated for those who are visually impaired, and thus must be replaced with a new bodily sense. Over the years there have been multiple attempts to determine the second best sense from which the brain can generate the most information, and to create a device that utilizes that sense to gather and relay the data quickly and efficiently. However, the sense that has gained the most favor among users and the most experimentation is that of touch. A haptic display device employs the sense of touch by breaking down an image viewed by the haptic display into pixels; each pixel is then translated to a certain vibrational frequency or electrical charge for the user to feel (depending on the brightness of the pixel). One can then distinguish the feeling of the square-like object through the device, however the main problem that exists among the current haptic display devices is the low-resolution output. The low resolution thus makes it difficult for a user to decipher between objects that share a similar shape, but are still completely different.

By considering a different method of delivering information to the brain via touch, it may become possible to create a haptic display that can relay environmental information to the brain in 64x64 resolution. The alternative solution is to replace the vibrating motors with vibrating cantilever beams, thus allowing more beams to take up a specific area in comparison to vibrating motors. Each beam will vary in length to establish its own natural frequency while also making it easier for each beam’s vibration to be controlled by a single microcontroller. Nathan Eastburn, a student who graduated in the spring of 2018, designed a wire-cutting machine that could pull the beams through a metal plate to strip the beam into smaller cross-sections and cut the beams into the very precise lengths. To further complete the machine, the mechanical aspects of the machine needed to be finalized and installed, specifically the air cylinder valve and blade attachments.

The following report provides the details and thought process in converting the given designs of the air pump and blade systems into the physical additions to the wire-cutting machine. Both systems have further parts that need to be purchased, components that must be manufactured, and/or redesigns to the functionality of the systems; these will be explained for those desiring to continue and complete the assembly of this machine.

This thesis presents the design and testing of a soft robotic device for water utility pipeline inspection. The preliminary findings of this new approach to conventional methods of pipe inspection demonstrate that a soft inflatable robot can successfully traverse the interior space of a range of diameter pipes using pneumatic and without the need to adjust rigid, mechanical components. The robot utilizes inflatable soft actuators with an adjustable radius which, when pressurized, can provide a radial force, effectively anchoring the device in place. Additional soft inflatable actuators translate forces along the center axis of the device which creates forward locomotion when used in conjunction with the radial actuation. Furthermore, a bio-inspired control algorithm for locomotion allows the robot to maneuver through a pipe by mimicking the peristaltic gait of an inchworm. This thesis provides an examination and evaluation of the structure and behavior of the inflatable actuators through computational modeling of the material and design, as well as the experimental data of the forces and displacements generated by the actuators. The theoretical results are contrasted with/against experimental data utilizing a physical prototype of the soft robot. The design is anticipated to enable compliant robots to conform to the space offered to them and overcome occlusions from accumulated solids found in pipes. The intent of the device is to be used for inspecting existing pipelines owned and operated by Salt River Project, a Phoenix-area water and electricity utility provider.

This research evaluated soft robotic knee brace designs that were intended to reduce the risk of injury, chronic pain, and osteoarthritis in laborers tasked with repetitive lifting. A soft robotic quasi-passive system was proposed due to energy efficiency, comfortability, and weight. The researcher developed three quasi-passive knee brace systems that would store energy when the user attempted a squat lift and release the energy when the user stood up. The first design focused on using clamped layered leaf springs to create an increased resistive force when the user bends at the knee. The researchers found that because of the unideal clamping of the springs the design failed to produce a significant increase to the forces the user experienced. The second design used a change in length of the layered leaf springs to provide a significant change in force. Through simple tests, the researchers found that the design did create a change in force significant enough to warrant further testing of the design in the future. The third and final design was inspired by a previous honors thesis by Ryan Bellman, this design used pre-stretched elastic bands to create an increased bending moment. Through experimental testing, the researchers found that the elastic bands created a factor increase of 8 from a non-loaded test. Further work would include prototyping a knee brace design and developing a method to allow the user to stretch and unstretch the elastic bands at will. In conclusion, design 2 and design 3 have the potential to significantly increase the well being of workers and increase their knee longevity.

For my thesis I worked in ASU’s Bio-Inspired Mechatronics lab on a project lead by PhD student Pham H. Nguyen (Berm) to develop an assistive soft robotic supernumerary limb. I contributed to the design and evaluation of two prototypes: the silicon based Soft Poly Limb (SPL) and one bladder-based fabric arm, the fabric Soft Poly Limb (fSPL). For both arms I was responsible for the design of 3D printed components (molds, end caps, etc.) as well as the evaluation of the completed prototypes by comparing the actual performance of the arms to the finite element predictions. I contributed to the writing of two published papers describing the design and evaluation of the two arms. After the completion of the fSPL I attempted to create a quasi-static model of the actuators driving the fSPL.

Laminate devices have the potential to lower the cost and complexity of robots. Taking advantage of laminate materials' flexibility, a high-performance jumping platform has been developed with the goal of optimizing jump ground clearance. Four simulations are compared in order to understand which dynamic model elements (leg flexibility, motor dynamics, contact, joint damping, etc.) must be included to accurately model jumping performance. The resulting simulations have been validated with experimental data gathered from a small set of physical leg prototypes spanning design considerations such as gear ratio and leg length, and one in particular was selected for the fidelity of performance trends against experimental results. This simulation has subsequently been used to predict the performance of new leg designs outside the initial design set. The design predicted to achieve the highest jump ground clearance was then built and tested as a demonstration of the usefulness of this simulation.

Geometrical tolerances define allowable manufacturing variations in the features of mechanical parts. For a given feature (planar face, cylindrical hole) the variations may be modeled with a T-Map, a hyper solid in 6D small displacement coordinate space. A general method for constructing T-Maps is to decompose a feature into points, identify the variational limits to these points allowed by the feature tolerance zone, represent these limits using linear halfspaces, transform these to the central local reference frame and intersect these to form the T-Map for the entire feature. The method is explained and validated for existing T-Map models. The method is further used to model manufacturing variations for the positions of axes in patterns of cylindrical features.

When parts are assembled together, feature level manufacturing variations accumulate (stack up) to cause variations in one or more critical dimensions, e.g. one or more clearances. When the T-Maps model is applied to complex assemblies it is possible to obtain as many as six dimensional stack up relation, instead of the one or two typical of 1D or 2D charts. The sensitivity of the critical assembly dimension to the manufacturing variations at each feature can be evaluated by fitting a functional T-Map over a kinematically transformed T-Map of the feature. By considering individual features and the tolerance specifications, one by one, the sensitivity of each tolerance on variations of a critical assembly level dimension can be evaluated. The sum of products of tolerance values and respective sensitivities gives value of worst case functional variation. The same sensitivity equation can be used for statistical tolerance analysis by fitting a Gaussian normal distribution function to each tolerance range and forming an equation of variances from all the contributors. The method for evaluating sensitivities and variances for each contributing feature is explained with engineering examples.

The overall objective of this research is to develop method for automation friendly and efficient T-Map generation and statistical tolerance analysis.

In this work, different methods for fabrication of flexible sensors and sensor characterization are studied. Using materials and equipment that is unconventional, it is shown that different processes can be used to create sensors that behave like commercially available sensors. The reason unconventional methods are used is to cut down on cost to produce the sensors as well as enabling the manufacture of custom sensors in different sizes and different configurations. Currently commercially available sensors are expensive and are usually designed for very specific applications. By creating these same types of sensors using new methods and materials, these new sensors will show that flexible sensor creation for many uses at a fraction of the cost is achievable.

The sensor industry is a growing industry that has been predicted by Allied Market Research to be a multi-billion industry by 2022. One of the many key drives behind this rapid growth in the sensor industry is the increase incorporation of sensors into portable electrical devices. The value for sensor technologies are increased when the sensors are developed into innovative measuring system for application uses in the Aerospace, Defense, and Healthcare industries. While sensors are not new, their increased performance, size reduction, and decrease in cost has opened the door for innovative sensor combination for portable devices that could be worn or easily moved around. With this opportunity for further development of sensor use through concept engineering development, three concept projects for possible innovative portable devices was undertaken in this research. One project was the development of a pulse oximeter devise with fingerprint recognition. The second project was prototyping a portable Bluetooth strain gage monitoring system. The third project involved sensors being incorporated onto flexible printed circuit board (PCB) for improved comfort of wearable devices. All these systems were successfully tested in lab.