Velocity and Color Estimation Using Event-Based Clustering

Event-based clustering provides a low-power embedded solution for low-level feature extraction in a scene. The algorithm utilizes the non-uniform sampling capability of event-based image sensors to measure local intensity variations within a scene. Consequently, the clustering algorithm forms similar event groups while simultaneously estimating their attributes. This work proposes taking advantage of additional event information in order to provide new attributes for further processing. We elaborate on the estimation of the object velocity using the mean motion of the cluster. Next, we are examining a novel form of events, which includes intensity measurement of the color at the concerned pixel. These events may be processed to estimate the rough color of a cluster, or the color distribution in a cluster. Lastly, this paper presents some applications that utilize these features. The resulting algorithms are applied and exercised thanks to a custom event-based simulator, which generates videos of outdoor scenes. The velocity estimation methods provide satisfactory results with a trade-off between accuracy and convergence speed. Regarding color estimation, the luminance estimation is challenging in the test cases, while the chrominance is precisely estimated. The estimated quantities are adequate for accurately classifying objects into predefined categories.

Untethered Soft Pneumatic Actuators with Embedded Multiple Sensing Capabilities

Pneumatic soft robot attracts extensive attention because of its own characteristics. It has great application potential in medical and other fields. Although the recent improvement of the soft robot shows great potentials for delicate manipulations, the development of completely untethered pneumatic intelligent soft robots remains challenging. This article introduces a novel type of untethered soft pneumatic actuator with embedded multiple sensing capabilities. The untethered drive of the soft pneumatic actuator is achieved by near-infrared-induced liquid-gas phase transition. In addition, a soft conductive resin was developed to make flexible sensors. Embedded flexible sensors enable bending and temperature sensing of soft actuators. With Digital Light Processing three-dimensional printing, the rapid fabrication of soft actuators and flexible sensors was realized. This article demonstrates the potential of the proposed untethered soft actuators with embedded multiple sensing capabilities as an important contribution to the research of completely untethered intelligent soft robots.

Biomimetic Soft Polymer Microstructures and Piezoresistive Graphene MEMS Sensors Using Sacrificial Metal 3D Printing

Recent advances in 3D printing technology have enabled unprecedented design freedom across an ever-expanding portfolio of materials. However, direct 3D printing of soft polymeric materials such as polydimethylsiloxane (PDMS) is challenging, especially for structural complexities such as high-aspect ratio (>20) structures, 3D microfluidic channels (∼150 μm diameter), and biomimetic microstructures. This work presents a novel processing method entailing 3D printing of a thin-walled sacrificial metallic mold, soft polymer casting, and acidic etching of the mold. The proposed workflow enables the facile fabrication of various complex, bioinspired PDMS structures (e.g., 3D double helical microfluidic channels embedded inside high-aspect ratio pillars) that are difficult or impossible to fabricate using currently available techniques. The microfluidic channels are further infused with conductive graphene nanoplatelet ink to realize two flexible piezoresistive microelectromechanical (MEMS) sensors (a bioinspired flow/tactile sensor and a dome-like force sensor) with embedded sensing elements. The MEMS force sensor is integrated into a Philips 9000 series electric shaver to demonstrate its application in "smart" consumer products in the future. Aided by current trends in industrialization and miniaturization in metal 3D printing, the proposed workflow shows promise as a low-temperature, scalable, and cleanroom-free technique of fabricating complex, soft polymeric, biomimetic structures, and embedded MEMS sensors.

Medication Adherence and Liquid Level Tracking System for Healthcare Provider Feedback

A common problem for healthcare providers is accurately tracking patients’ adherence to medication and providing real-time feedback on the management of their medication regimen. This is a particular problem for eye drop medications, as the current commercially available monitors focus on measuring adherence to pills, and not to eye drops. This work presents an intelligent bottle sleeve that slides onto a prescription eye drop medication bottle. The intelligent sleeve is capable of detecting eye drop use, measuring fluid level, and sending use information to a healthcare team to facilitate intervention. The electronics embedded into the sleeve measure fluid level, dropper orientation, the state of the dropper top (on/off), and rates of angular motion during an application. The sleeve was tested with ten patients (age ≥65) and successfully identified and timestamped 94% of use events. On-board processing enabled event detection and the measurement of fluid levels at a 0.4 mL resolution. These data were communicated to the healthcare team using Bluetooth and Wi-Fi in real-time, enabling rapid feedback to the subject. The healthcare team can therefore monitor a log of medication use behavior to make informed decisions on treatment or support for the patient.

Experimental Investigation into the Dynamics of a Radially Contracting Actuator with Embedded Sensing Capability

Dynamics, control, and sensing are still challenges for pneumatically actuated soft actuators. We consider feasible solutions based on a radially contracting actuator to overcome these challenges. The radially contracting actuator was inspired by the movement of the stomach wall. It was capable of achieving radial contraction by inflating its circular air chamber. A quasi-static model that relates the pressure with the deformed wall of the air chamber was proposed and validated. In this article, we conduct a thorough experimental investigation into the contracting dynamics of the actuator with embedded sensing capability. We analyze the kinematics of the actuator at its rest and pressurization states focusing on the midpoint of the deformed wall. The actuator dynamics is characterized under the square wave pressure input by two variables that are the pressure in the air chamber and the trajectories of the midpoint. To achieve the desired contraction, we construct a feed-forward control based on the quasi-static model. It proves that the actuator is capable of tracking a prescribed triangular wave displacement of the midpoint with small deviations. A custom-made soft sensor is integrated into the actuator, which brings in the embedded sensing capability without affecting the actuator compliance. The resistance changes of the sensor versus the controlled contraction are examined, which are used to indicate the amount of radial contraction. The experimental investigation provides a foundation for the closed-loop control and practical applications of the radially contracting actuator developed.

Smart Build-Plate for Metal Additive Manufacturing Processes

This paper discusses the development, processing steps, and evaluation of a smart build-plate or baseplate tool for metal additive manufacturing technologies. This tool uses an embedded high-definition fiber optic sensing fiber to measure strain states from temperature and residual stress within the build-plate for monitoring purposes. Monitoring entails quality tracking for consistency along with identifying defect formation and growth, i.e., delamination or crack events near the build-plate surface. An aluminum alloy 6061 build-plate was manufactured using ultrasonic additive manufacturing due to the process' low formation temperature and capability of embedding fiber optic sensing fiber without damage. Laser-powder bed fusion (L-PBF) was then used to print problematic geometries onto the build-plate using AlSi10Mg for evaluation purposes. The tool identified heat generation, delamination onset, and delamination growth of the printed L-PBF parts.

Barium Titanate Film Interfaces for Hybrid Composite Energy Harvesters

Energy harvesting utilizing piezoelectric materials has become an attractive approach for converting mechanical energy into electrical power for low-power electronics. Structural composites are ideally suited for energy scavenging due to the large amount of mechanical energy they are subjected to. Here, a multifunctional composite with embedded sensing and energy harvesting is developed by integrating an active interface into carbon fiber reinforced polymer composites. By modifying the composite matrix, both rigid and flexible multifunctional composites are fabricated. Through electromechanical testing of a cantilever beam of the rigid composite, it reveals a power density of 217 pW/cc from only 1 g root-mean-square acceleration when excited at its resonant frequency of 47 Hz. Electromechanical sensor testing of the flexible multifunctional composite reveals an average voltage generation of 23.5 mV/g at its resonant frequency of 96 Hz. This research introduces a route for integrating nonstructural functionality into structural fiber composites by utilizing BaTiO₃ coated woven carbon fiber fabrics with power scavenging and passive sensing capabilities.