Materials science and the sensor revolution

For the past decade, we have been investigating strategies to develop ways to provide chemical sensing platforms capable of long-term deployment in remote locations1-3. This key objective has been driven by the emergence of ubiquitous digital communications and the associated potential for widely deployed wireless sensor networks (WSNs). Understandably, in these early days of WSNs, deployments have been based on very reliable sensors, such as thermistors, accelerometers, flow meters, photodetectors, and digital cameras. Biosensors and chemical sensors (bio/chemo-sensors) are largely missing from this rapidly developing field, despite the obvious value offered by an ability to measure molecular targets at multiple locations in real-time. Interestingly, while this paper is focused on the issues with respect to wide area sensing of the environment, the core challenge is essentially the same for long-term implantable bio/chemo-sensors4, i.e.; how to maintain the integrity of the analytical method at a remote, inaccessible location

Design and analysis of a high performance valve

Most valves available in the fluid power industry today are capable of achieving either a large flow rate or a quick response time; however, often they are unable to deliver both simultaneously. Commercially available valves that can produce both at the same time require complex geometries with multiple actuation stages and piloting pressures, making them expensive components. To establish their active usage in applications across the fluid power industry, a reduction in price for these components is paramount. The Energy Coupling Actuated Valve (ECAV) is capable of solving the large flow rates with fast actuation speeds trade-off by utilizing a new, high performance actuation system. The Energy Coupling Actuator (ECA) is an innovative actuation system that separates the kinetic energy source mass from the actuation mass. Intermittently coupling the actuator to a constantly rotating disk creates an energy transfer from the rotating disk’s kinetic energy to the normally stationary actuator. This intermittent coupling process is controlled by changing the magnetic field inside the actuator’s two coils. Magnetorheological (MR) fluid resides in a 0.5mm fluid gap between the spinning disk and the actuator, and when the magnetic flux builds across this gap, it causes the actuator to move rapidly in a translational movement. The MR fluid changes to a solid between the gap and frictionally binds the actuator to the disk, causing the actuator to move up or down, depending on which coil is actuated on the spinning disk. The liquid-solid conversion from the MR fluid occurs in less than one millisecond and is completely reversible. The shear strength of the fluid is proportional to the magnetic field strength inside the system. The actuator is connected to either a poppet or spool assembly for valve actuation, and the position is controlled through intermittently binding the actuator to the disk. Two valve prototypes, one poppet and one spool type, were machined, and concept validation has been done in both simulation and experimentally. Experimental results show that the poppet reaches a 4mm displacement in 19.8ms opening and 17ms in closing under 33 L/min flow. The spool valve experimentally transitioned in 4.8ms at the same flow rate

MotorSkins—a bio-inspired design approach towards an interactive soft-robotic exosuit

The work presents a bio-inspired design approach to a soft-robotic solution for assisting the knee-bending in users with reduced mobility in lower limbs. Exosuits and fluid-driven actuators are fabric-based devices that are gaining increasing relevance as alternatives assistive technologies that can provide simpler, more flexible solutions in comparison with the rigid exoskeletons. These devices, however, commonly require an external energy supply or a pressurized-fluid reservoir, which considerably constrain the autonomy of such solutions. In this work, we introduce an event-based energy cycle (EBEC) design concept, that can harvest, store, and release the required energy for assisting the knee-bending, in a synchronised interaction with the user and the environment, thus eliminating any need for external energy or control input. Ice-plant hydro-actuation system served as the source of inspiration to address the specific requirements of such interactive exosuit through a fluid-driven material system. Based on the EBEC design concepts and the abstracted bio-inspired principles, a series of (material and process driven) design experimentations helped to address the challenges of realising various functionalities of the harvest, storage, actuation and control instances within a closed hydraulic circuit. Sealing and defining various areas of water-tight seam made out of thermoplastic elastomers provided the base material system to program various chambers, channels, flow-check valves etc of such EBEC system. The resulting fluid-driven EBEC-skin served as a proof of concept for such active exosuit, that brings these functionalities into an integrated ‘sense-acting’ material system, realising an auto-synchronised energy and information cycles. The proposed design concept can serve as a model for development of similar fluid-driven EBEC soft-machines for further applications. On the more general scheme, the work presents an interdisciplinary design-science approach to bio-inspiration and showcases how biological material solutions can be looked at from a design/designer perspective to bridge the bottom–up and top–down approach to bio-inspiration.Deutsche Forschungsgemeinschafthttps://doi.org/10.13039/501100001659Peer Reviewe

A Robust Adaptive Hydraulic Power Generation System for Jet Engines

The paper presents an innovative hydraulic power generation system able to enhance performance, reliability and survivability of hydraulic systems used in military jet engines, as well as to allow a valuable power saving. This is obtained by a hydraulic power generation system architecture that uses variable pressure, smart control, emergency power source and suitable health management procedures. A key issue is to obtain all these functions while reducing to a minimum the number of additional components with respect to the conventional hydraulic power generation systems. The paper firstly presents the state-of-art of these systems and their critical issues, outlines the alternative solutions, and then describes architecture, characteristics and performance of the hydraulic power generation system that was eventually defined as a result of a research activity aimed at moving beyond the present state-of-art in this fiel

INTERNAL COMBUSTION ENGINE COOLING STRATEGIES: THEORY AND TEST

Advanced internal combustion engine thermal management systems can enhance overall engine performance through the use of computer controlled cooling system actuators. Existing ground vehicle cooling systems generally have performance limitations due to the fixed behavior of the wax-based thermostat valve and crankshaft dependent operation of the coolant pump and radiator fan. Upgrading the traditional thermostat valve, water pump, and radiator fan with actuators permit real time computer control for improved temperature tracking and reduced power consumption. In this paper, the benefits associated with advanced automotive cooling systems are experimentally investigated. A 4.6L engine with a real-time data acquisition and control system facilitated the investigation of cooling system configurations. The experimental results demonstrate that the smart thermostat valve and variable speed radiator fan offer a 42% power consumption reduction. Also, when pump control is implemented, power consumption reductions are 88%, in comparison to the factory emulated cooling system configuration. With this increased level of control, efficient controller designs have been realized for the cooling system configurations as well as accurate steady state temperature tracking