Quantifying Information without Entropy: Identifying Intermittent Disturbances in Dynamical Systems.

A system's response to disturbances in an internal or external driving signal can be characterized as performing an implicit computation, where the dynamics of the system are a manifestation of its new state holding some memory about those disturbances. Identifying small disturbances in the response signal requires detailed information about the dynamics of the inputs, which can be challenging. This paper presents a new method called the Information Impulse Function (IIF) for detecting and time-localizing small disturbances in system response data. The novelty of IIF is its ability to measure relative information content without using Boltzmann's equation by modeling signal transmission as a series of dissipative steps. Since a detailed expression of the informational structure in the signal is achieved with IIF, it is ideal for detecting disturbances in the response signal, i.e., the system dynamics. Those findings are based on numerical studies of the topological structure of the dynamics of a nonlinear system due to perturbated driving signals. The IIF is compared to both the Permutation entropy and Shannon entropy to demonstrate its entropy-like relationship with system state and its degree of sensitivity to perturbations in a driving signal.

Technology-forcing to reduce environmental noise pollution: a prospectus.

BACKGROUND: Environmental movements of the late 20th century resulted in sweeping legislation and regulatory actions to reduce the prevalence of diverse pollutants. Although the consequences of noise pollution to public health, environment, and the economy have been recognized over the same time period, noise has received far less policy attention. Correspondingly, even while evidence of the diverse and detrimental effects of noise pollution on human health has grown, solutions and actual reductions in environmental noise remain seemingly out of reach. OBJECTIVE: To address this shortcoming, we developed a prospectus for environmental noise reduction through technology-forcing policies. Technology-forcing describes intent to encourage technological solutions for pollution control through policy and regulations, and has been a critical component of national and global progress in reducing environmental pollutants. METHODS: We take advantage of the unique policy history for noise in the United States - which initially enacted, but then abandoned federal noise regulation. We compare this history against outcomes from contemporaneous environmental legislation for air, water, and occupational pollution control, to demonstrate the potential for technology-forcing to reduce noise pollution. Our review then identifies promising solutions, in the form of existing technologies suitable for innovation and diffusion through technology-forcing regulations and incentives. RESULTS: Based on this review, we outline a program for noise policy development to support efforts to reduce environmental noise pollution worldwide. The proposed program consists of three steps, which are to (i) identify dominant sources of noise pollution, (ii) combine legislative or regulatory provisions with suitable systems of enforcement and incentives, and (iii) anticipate and prepare for stages of technological change. IMPACT STATEMENT: Analysis of noise policy often focuses on justifying the need to reduce noise pollution. In this article, we demonstrate how technology-forcing regulations could also promote much-needed innovation and diffusion of technologies to reduce environmental noise pollution. We first establish the potential for technology-forcing by comparing technology outcomes from environmental legislation passed contemporaneously to the inactive US Noise Control Act. We next review promising innovations available for diffusion in multiple sectors to reduce environmental noise. Lastly, we recommend a program to support development of technology-forcing noise policies, to help ensure that the benefits of reduced noise pollution are distributed equitably.

Editorial for the Special Issue on 3D Printed Actuators.

After decades of curiosity-driven innovation and engineering advancements of 3D-printed actuators, we continue to witness their endless impacts and ever-expanding opportunities in many applications that touch our lives [...].

Hybrid Compliant Musculoskeletal System for Fast Actuation in Robots.

A nature-inspired musculoskeletal system is designed and developed to examine the principle of nonlinear elastic energy storage-release for robotic applications. The musculoskeletal system architecture consists of elastically rigid segments and hyperelastic soft materials to emulate rigid-soft interactions in limbless vertebrates. The objectives are to (i) improve the energy efficiency of actuation beyond that of current pure soft actuators while (ii) producing a high range of motion similar to that of soft robots but with structural stability. This paper proposes a musculoskeletal design that takes advantage of structural segmentation to increase the system's degrees of freedom, which enhances the range of motion. Our findings show that rigid-soft interactions provide a remarkable increase in energy storage and release and, thus, an increase in the undulation speed. The energy efficiency achieved is approximately 68% for bending the musculoskeletal system from the straight configuration, compared to 2.5-30% efficiency in purely soft actuators. The hybrid compliance of the musculoskeletal system under investigation shows promise for alleviating the need for actuators at each joint in a robot.

Untethered Stretchable Displays for Tactile Interaction.

Although physical buttons provide tactile sensations that allow them to be identified and pressed without visual focus, their static nature limits their use for dynamic interfaces. Conversely, touchscreens offer highly flexible, task-specific interfaces, but they do not provide the tactile qualities needed for vision-free interaction. Here, we present a stretchable display that can change shape from a flat sheet into a dome when pressurized. The vanishing interface we designed uses hyperelastic light-emitting capacitors (HLECs) that actively emit light, sense strain, and detect finger presses. We characterize the stretch and luminance of the device as the thin sheet is pressurized. Interestingly, but not unexpectedly, these HLEC panels show a pressure-dependent luminance, which we use to highlight where they are being pressed, a visual display of haptic information. We further demonstrate the co-located touch sensing and light-emitting capabilities by developing an interactive memory game.

3D Printed Electrically-Driven Soft Actuators.

Soft robotics is an emerging field enabled by advances in the development of soft materials with properties commensurate to their biological counterparts, for the purpose of reproducing locomotion and other distinctive capabilities of active biological organisms. The development of soft actuators is fundamental to the advancement of soft robots and bio-inspired machines. Among the different material systems incorporated in the fabrication of soft devices, ionic hydrogel-elastomer hybrids have recently attracted vast attention due to their favorable characteristics, including their analogy with human skin. Here, we demonstrate that this hybrid material system can be 3D printed as a soft dielectric elastomer actuator (DEA) with a unimorph configuration that is capable of generating high bending motion in response to an applied electrical stimulus. We characterized the device actuation performance via applied (i) ramp-up electrical input, (ii) cyclic electrical loading, and (iii) payload masses. A maximum vertical tip displacement of 9.78 ± 2.52 mm at 5.44 kV was achieved from the tested 3D printed DEAs. Furthermore, the nonlinear actuation behavior of the unimorph DEA was successfully modeled using analytical energetic formulation and a finite element method (FEM).