687 research outputs found

    Dual Mode Control of an Inverted Pendulum: Design, Analysis and Experimental Evaluation

    Get PDF
    We present an inverted pendulum design using readily available V-slot rail components and 3D printing to construct custom parts. To enable the examination of different pendulum characteristics, we constructed three pendulum poles of different lengths. We implemented a brake mechanism to modify sliding friction resistance and built a paddle that can be attached to the ends of the pendulum poles. A testing rig was also developed to consistently apply disturbances by tapping the pendulum pole, characterizing balancing performance. We perform a comprehensive analysis of the behavior and control of the pendulum. This begins by considering its dynamics, including the nonlinear differential equation that describes the system, its linearization, and its representation in the s-domain. The primary focus of this work is the development of two distinct control modes for the pendulum: a velocity control mode, designed to balance the pendulum while the cart is in motion, and a position control mode, aimed at maintaining the pendulum cart at a specific location. For this, we derived two different state space models: one for implementing the velocity control mode and another for the position control mode. In the position control mode, integral action applied to the cart position ensures that the inverted pendulum remains balanced and maintains its desired position on the rail. For both models, linear observer-based state feedback controllers were implemented. The control laws are designed as linear quadratic regulators (LQR), and the systems are simulated in MATLAB. To actuate the physical pendulum system, a stepper motor was used, and its controller was assembled in a DIN rail panel to simplify the integration of all necessary components. We examined how the optimized performance, achieved with the medium-length pendulum pole, translates to poles of other lengths. Our findings reveal distinct behavioral differences between the control modes

    Fast Sensing and Adaptive Actuation for Robust Legged Locomotion

    Get PDF
    Robust legged locomotion in complex terrain demands fast perturbation detection and reaction. In animals, due to the neural transmission delays, the high-level control loop involving the brain is absent from mitigating the initial disturbance. Instead, the low-level compliant behavior embedded in mechanics and the mid-level controllers in the spinal cord are believed to provide quick response during fast locomotion. Still, it remains unclear how these low- and mid-level components facilitate robust locomotion. This thesis aims to identify and characterize the underlining elements responsible for fast sensing and actuation. To test individual elements and their interplay, several robotic systems were implemented. The implementations include active and passive mechanisms as a combination of elasticities and dampers in multi-segment robot legs, central pattern generators inspired by intraspinal controllers, and a synthetic robotic version of an intraspinal sensor. The first contribution establishes the notion of effective damping. Effective damping is defined as the total energy dissipation during one step, which allows quantifying how much ground perturbation is mitigated. Using this framework, the optimal damper is identified as viscous and tunable. This study paves the way for integrating effective dampers to legged designs for robust locomotion. The second contribution introduces a novel series elastic actuation system. The proposed system tackles the issue of power transmission over multiple joints, while featuring intrinsic series elasticity. The design is tested on a hopper with two more elastic elements, demonstrating energy recuperation and enhanced dynamic performance. The third contribution proposes a novel tunable damper and reveals its influence on legged hopping. A bio-inspired slack tendon mechanism is implemented in parallel with a spring. The tunable damping is rigorously quantified on a central-pattern-generator-driven hopping robot, which reveals the trade-off between locomotion robustness and efficiency. The last contribution explores the intraspinal sensing hypothesis of birds. We speculate that the observed intraspinal structure functions as an accelerometer. This accelerometer could provide fast state feedback directly to the adjacent central pattern generator circuits, contributing to birds’ running robustness. A biophysical simulation framework is established, which provides new perspectives on the sensing mechanics of the system, including the influence of morphologies and material properties. Giving an overview of the hierarchical control architecture, this thesis investigates the fast sensing and actuation mechanisms in several control layers, including the low-level mechanical response and the mid-level intraspinal controllers. The contributions of this work provide new insight into animal loco-motion robustness and lays the foundation for future legged robot design

    Self-learning mechanical circuits

    Full text link
    Computation, mechanics and materials merge in biological systems, which can continually self-optimize through internal adaptivity across length scales, from cytoplasm and biofilms to animal herds. Recent interest in such material-based computation uses the principles of energy minimization, inertia and dissipation to solve optimization problems. Although specific computations can be performed using dynamical systems, current implementations of material computation lack the ability to self-learn. In particular, the inverse problem of designing self-learning mechanical systems which can use physical computations to continuously self-optimize remains poorly understood. Here we introduce the concept of self-learning mechanical circuits, capable of taking mechanical inputs from changing environments and constantly updating their internal state in response, thus representing an entirely mechanical information processing unit. Our circuits are composed of a new mechanical construct: an adaptive directed spring (ADS), which changes its stiffness in a directional manner, enabling neural network-like computations. We provide both a theoretical foundation and experimental realization of these elastic learning units and demonstrate their ability to autonomously uncover patterns hidden in environmental inputs. By implementing computations in an embodied physical manner, the system directly interfaces with its environment, thus broadening the scope of its learning behavior. Our results pave the way towards the construction of energy-harvesting, adaptive materials which can autonomously and continuously sense and self-optimize to gain function in different environments

    Advanced Materials and Technologies in Nanogenerators

    Get PDF
    This reprint discusses the various applications, new materials, and evolution in the field of nanogenerators. This lays the foundation for the popularization of their broad applications in energy science, environmental protection, wearable electronics, self-powered sensors, medical science, robotics, and artificial intelligence

    Designing a New Tactile Display Technology and its Disability Interactions

    Get PDF
    People with visual impairments have a strong desire for a refreshable tactile interface that can provide immediate access to full page of Braille and tactile graphics. Regrettably, existing devices come at a considerable expense and remain out of reach for many. The exorbitant costs associated with current tactile displays stem from their intricate design and the multitude of components needed for their construction. This underscores the pressing need for technological innovation that can enhance tactile displays, making them more accessible and available to individuals with visual impairments. This research thesis delves into the development of a novel tactile display technology known as Tacilia. This technology's necessity and prerequisites are informed by in-depth qualitative engagements with students who have visual impairments, alongside a systematic analysis of the prevailing architectures underpinning existing tactile display technologies. The evolution of Tacilia unfolds through iterative processes encompassing conceptualisation, prototyping, and evaluation. With Tacilia, three distinct products and interactive experiences are explored, empowering individuals to manually draw tactile graphics, generate digitally designed media through printing, and display these creations on a dynamic pin array display. This innovation underscores Tacilia's capability to streamline the creation of refreshable tactile displays, rendering them more fitting, usable, and economically viable for people with visual impairments

    Understanding intestinal and pancreatic hormone secretion in health and type 2 diabetes: (pre-)clinical studies and technical innovations

    Get PDF
    The gastrointestinal (GI) tract and pancreatic islets are key components of the endocrine system, responsible for the release of an array of peptide hormones, which orchestrate metabolic homeostasis through regulation of energy intake, nutrient digestion, absorption and metabolism. Of numerous hormones released from the gut, the incretin hormones, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), govern the secretion of both insulin and glucagon from pancreatic islets. Together, these hormones play a critical role in maintaining glucose homeostasis. Disrupted secretion and/or action of the incretins and pancreatic hormones underpins the development of type 2 diabetes (T2D) - a global epidemic characterised by elevated blood glucose concentrations and associated with devastating micro- and macro-vascular complications. Accordingly, an improved understanding of the physiology and pathophysiology of GI and pancreatic hormones in health and T2D is of major relevance to the development of effective strategies to both prevent and better manage T2D. This thesis comprises a series of clinical and preclinical evaluations that provide novel insights into the determinants of GI and islet hormone secretion (Chapters 3-6). In addition, it details the cross-disciplinary collaborative development of two ‘organ-on-a-chip’ platforms for dissecting the secretory function of both intestinal tissues and pancreatic islets (Chapters 7-8). Chapter 1 provides an overview of the secretion and action of GI hormones arising from the complex interaction between luminal nutrients/bioactive compounds and the gut mucosa, and details conventional and innovative research tools/platforms that are indispensable for the investigation of GI hormone secretion. Chapter 2 summarises the molecular mechanisms underlying insulin secretion from pancreatic islets, with a focus on the role of Ca2+ signalling, and systematically reviews the development of diverse research platforms that are fundamental to progressing islet research. Given the substantial sex-related differences in glucose metabolism and risk of T2D, the study described in Chapter 3 explores the sex disparity in incretin hormone secretion, and compares the incretin and glycaemic responses to standardised intraduodenal glucose infusions within the physiological range of gastric emptying between healthy young men and women. While insulin resistance and consequently a relative deficiency in insulin secretion are recognised as key metabolic derangements in T2D, there is accumulating evidence indicating that excessive glucagon secretion also underpins the development of dysglycaemia during both the fasting and postprandial phases. In the liver, insulin and glucagon signalling pose counter-regulatory effects on hepatic glucose production. Alterations in hepatic function have the potential to disrupt hepatic insulin and glucagon signalling, leading to pathological changes in insulin and glucagon secretion. The study reported in Chapter 4 evaluates the relationships of blood glucose, plasma insulin, C-peptide and glucagon, both during fasting and after 75g oral glucose, with serum liver enzymes in healthy and T2D subjects, and in T2D subjects before and after a mixed meal. Given the major role of the rate of gastric emptying (GE) in determining nutrient digestion and absorption, GE may influence the glucagon and glycaemic responses in T2D. Therefore, Chapter 5 further examines the relationships of plasma glucagon and blood glucose with the rate of gastric emptying (GE) of a standardised mashed potato meal in individuals with well-controlled T2D. Strategies that are effective for modulating GI and pancreatic hormone secretion have the potential to improve glycaemic control in T2D. The recent recognition that the GI tract can detect a range of physiological and pharmacological bitter substances via a family of type 2 monomeric G-protein-coupled receptors, namely bitter taste receptors (BTRs), to release GI hormones has led to growing interest in the administration of bitter tastants to stimulate GI hormone secretion for the management of metabolic disorders, including T2D. However, the effects of bitter substances beyond the GI tract have received little attention. Chapter 6 reports the effect of a bitter substance, denatonium benzoate (DB), on insulin secretion in a series of in vitro and ex vivo experiments using a rodent pancreatic β-cell line, INS-1 832/13 cells, and isolated mouse pancreatic islets. In the latter, the effects of DB on the secretion of other islet hormones, including glucagon, GLP-1 and somatostatin, were also characterised. While the currently available cell/tissue models and in vivo tools have substantially advanced the knowledge on the physiology and pathophysiology of incretins and islet hormones, there is rising demand for sophisticated biomimetic platforms to address the increasingly complicated biological challenges and improve the translational success from benchtop to bedside. To this end, the development of a gut-on-a-chip (GOC) system is described in Chapter 7 which facilitates continuous monitoring of dynamic GLP-1 secretion from primary mouse intestinal tissue. Similarly, the development and customisation of a microfluidic sensing platform is described in Chapter 8, allowing quantification of the dynamic changes of Ca2+ and insulin concurrently, enabling investigation of the secretory function of isolated islets.Thesis (Ph.D.) -- University of Adelaide, Adelaide Medical School, 202

    M-CDS: Mobile Carbohydrate Delivery System

    Get PDF
    When patients with type 1 diabetes (T1D) are physically active, they encounter an issue with keeping their blood glucose (BG) stable. Generally, their blood glucose level (BGL) will drop, causing hypoglycaemia which can have fatal consequences. The simple solution is to consume carbohydrates in the form of liquids or food, but during physical activities, it can be difficult to follow their BGL at the same time as they exercise. This thesis presents the design and implementation of a mobile carbohydrate delivery system, M-CDS. Previous work has shown that it is possible to create a stationary carbohydrate delivery system that reads the user’s BG data in real-time, gives feedback to the user when their BGL is nearing hypoglycaemia, and issues a dose of juice with 15 grams of carbohydrates. The proof-of-concept system in this thesis has the same functions but is contained within a modified CamelBak backpack. A Raspberry Pi, together with various sensors and a peristaltic pump, can transfer juice from a drinking reservoir to a drinking tube, which the user can easily drink from while physically active. The results show that the backpack works as intended and was able to avoid a BGL under 3.9 mmol/L while testing the system with a user using physical activity, thus successfully avoiding a hypoglycaemic event. As the system is a proof-of-concept, many things can be improved or modified to create a more robust, user-friendly, compact, and complex system. However, creating a prototype proved to be a time-costly project, whereas future work can use this project as a base to further improve it

    Challenges and Barriers of Wireless Charging Technologies for Electric Vehicles

    Get PDF
    Electric vehicles could be a significant aid in lowering greenhouse gas emissions. Even though extensive study has been done on the features and traits of electric vehicles and the nature of their charging infrastructure, network modeling for electric vehicle manufacturing has been limited and unchanging. The necessity of wireless electric vehicle charging, based on magnetic resonance coupling, drove the primary aims for this review work. Herein, we examined the basic theoretical framework for wireless power transmission systems for EV charging and performed a software-in-the-loop analysis, in addition to carrying out a performance analysis of an EV charging system based on magnetic resonance. This study also covered power pad designs and created workable remedies for the following issues: (i) how power pad positioning affected the function of wireless charging systems and (ii) how to develop strategies to keep power efficiency at its highest level. Moreover, safety features of wireless charging systems, owing to interruption from foreign objects and/or living objects, were analyzed, and solutions were proposed to ensure such systems would operate as safely and optimally as possible
    • …
    corecore