Present Design Method Research Articles

Quantized control for interconnected PDE systems via mobile measurement and control strategies

This paper deals with the Rϵ-stabilization for interconnected partial differential equation systems (IPDESs) by mobile measurement and control strategies. First, compared to the static measurement and control strategies, the mobile ones are employed to improve the dynamic response of the closed-loop system, while reducing the number of sensors and actuators effectively. Moreover, considering the constrained transmission channel bandwidth, the hysteresis quantizer with an adjustable parameter is introduced to save the communication resources in the network, while can balance the quantization effect and the control performance by adjusting the parameter. Further, the output quantization controller is designed to ensure that the closed-loop system is Rϵ-stable, which converges to a given interval in finite time. Finally, a simulation example of chemical non-isothermal tubular reactors is provided to illustrate the validity of the presented design method.

Synthesis and cross-section design of a new family of single-loop 7R deployable polygon mechanisms

In this paper, two design methods for different stages in the development of a single-degree-of-freedom (DOF) single-loop 7R deployable polygon mechanism (DGM) without overconstraints are presented, encompassing schematic synthesis and cross-section design methods for 7R DGMs. Firstly, two classes of revolute pair axes in DGMs are reviewed, detailing their value ranges and parameter definitions. A schematic synthesis method for single-DOF single-loop 7R DGMs is then proposed, followed by the development of a cross-section design method to enable desired cross-sections in these mechanisms. By applying these methods, three types of 7R DGMs were created and prototyped, with their folding sequences demonstrated and input singularity analysis conducted. Through the utilization of the presented design method, all single-DOF single-loop 7R DGMs can be designed. This work introduces a new family of DGMs and addresses the gap in the domain of general spatial single-DOF single-loop DGMs that are not overconstrained. It demonstrates the feasibility of designs whose expanded shapes form general planar polygons. This effort expands the variety and quantity of DGMs, paving the way for more innovative deployable network mechanisms.

Design of constant-force mechanisms using origami

The origami mechanisms possess numerous unique advantages, including folding, reconfigurability, and multi-stability. The presence of multi-stability introduces a novel concept for the design of constant force mechanisms (CFM). In this study, we present a CFM with multi-segment constant-force regions by leveraging the multi-stable characteristics of the origami mechanism. The design principle behind this CFM involves combining an accordion origami structure with positive stiffness and a Kresling origami structure with multi-segment negative stiffness regions. To achieve zero stiffness, the Kresling origami structure is aligned parallel to the accordion origami. To effectively utilize both the Kresling and accordion origamis, we have established a mechanical model that describes their respective stiffness characteristics to establish design rules for the constant-force mechanism. By carefully designing the parameters of these two origami structures, we evaluate how variations in the structural parameters of Kresling influence the constant force properties of our proposed multi-segment CFM. To illustrate its inherent property of providing constant force across multiple segments, we employ finite element analysis and experiments to obtain force-displacement curves for our mechanism. The results demonstrate the feasibility of our presented design method which paves the way for constructing a simple CFM.

Dynamic output feedback control for CPSs under transmission delays and sparse malicious attacks

In this paper, we study a class of discrete-time cyber-physical systems (CPSs) with transmission delays and sparse malicious attacks on both input and output transmission channels, and present design methods for secure observer and controller. First, the states and sparse malicious attacks of the original system are reorganized into the states of the new system obtained by an improved augmentation method (rather than a singular augmentation method). Then, based on the new system, the states and attacks can be reconstructed simultaneously by the designed Luenberger-like observer. Furthermore, a novel dynamic output feedback (DOF) controller is proposed using the estimated values of the attacks, and a cone complementarity linearization (CCL) algorithm is designed to obtain the controller gains. The results show that the closed-loop system is stable in the sense of Lyapunov that both the estimation errors and the original system states will converge to a small neighborhood of the origin. In addition, the correlation results without delay are given. Finally, two examples are given to illustrate the effectiveness and superiority of the proposed method.

On the design of multi-vortex beam multiplexers using programmable metasurfaces

This paper presents an analytical procedure for designing orbital angular momentum (OAM) multiplexers with the capability of generating multiple multiplexed beams with different directions and OAM mode indices. The presented design method provides independent control of the power of each output OAM mode in a multiplexed beam. As a proof of concept, a metasurface with four incident beams and two multiplexed scattered beams with different directions and OAM modes is designed. It is based on a 2/2 bits phase–amplitude programmable metasurface which is numerically simulated, and the results are in good agreement with analytical predictions. The presented approach paves the way for design and implementation of multifunctional devices specially used in OAM communication systems.

Adaptive robust output tracking of uncertain strict-feedback nonlinear systems with full state constraints via control schemes with simple structure

In this paper, the problem of output tracking control is considered for a class of uncertain strict-feedback nonlinear systems with virtual control coefficients and full state constraints. It is assumed only that the nonlinear uncertainties of the systems are some smooth functions enough to guarantee the existence of solutions to the differential equations which describe uncertain systems, and that the virtual control coefficients are unknown. Based on backstepping algorithm, by combining the barrier Lyapunov function with an integral inequality reported in the current control literature, a design method is presented whereby a simple adaptive robust output tracking control scheme can be synthesised. The presented design method can evade the repeated differentiation problem appearing in using backstepping algorithm, and need not know all the nonlinear upper bounds of uncertainties, which are repeatedly employed at each step of backstepping procedure. It is also shown that the output tracking error of the uncertain nonlinear systems with both unknown virtual control coefficients and full state constraints can converge uniformly exponentially towards a ball which can be as small as desired. Finally, a numerical example is given, and the corresponding simulations are also implemented to demonstrate the simplicity of the proposed method and the validity of the theoretical results.

Economic Implementation of 99.98% Efficiency in Natural-Cooling Modular MVDC SSCBs

This paper presents a modular medium voltage direct-current (MVDC) solid-state circuit breaker (SSCB) with high efficiency. The presented design method is modularity oriented, which includes thermal analysis of conduction cell, busbar design of conduction disk, and structure design of conduction tower. The implementation includes both continuous current conduction and fault current interruption. This paper includes three major contributions. First, it presents an economic analysis in terms of efficiency and cost as the design guideline for the main conduction configuration of SSCBs. Second, it provides a complete modular SSCB design procedure, showing both parallel and cascade scalability. Third, this paper investigates the effect of main conduction path stray resistances on SSCB efficiency and power loss. A medium-voltage SSCB prototype rated at 4kV/100A are experimentally implemented. The power density achieves 26.2 kW/L. The continuous conduction tests are conducted at 100A for 1hour, the steady-state efficiency achieves 99.98% with maximum temperature of 37°C. The fault interruption tests are successfully conducted at 4 kV/ 137A and 4 kV/ 1 kA with different system inertia.

Specifying task allocation in automotive wire harness assembly stations for Human-Robot Collaboration

Wire harness assembly is normally a manual assembly process that poses ergonomic challenges. As a consequence of the rapidly expanding electrification of vehicles and transportation systems, the demand for wire harnesses can be expected to grow radically, further increasing assembly operator challenges. Thus, automating this assembly process is highly prioritised by production engineers. The rapid development of industrial robot technology has enabled more human-robot collaboration possibilities, simplifying the automation of wire harness process tasks. However, successful automation applications involving humans require efficient and safe allocation of tasks between humans and technology. Unfortunately, present assembly system design methods may be obsolete and insufficient in light of the capabilities of emerging automation technologies such as collaborative robots. This paper presents a design and specification methodology for human-centred manufacturing systems and focuses on collaborative assembly operations in complex production systems. A case study on human-robot collaboration provides an application example from a wire-harness collaborative assembly process. The proposed design methodology combines hierarchical task analysis with assessments of cognitive and physical Levels of Automation (LoAc and LoAp). The assessments are then followed by evaluations of the Levels of human-robot Collaboration (LoC) and the Levels of operator Skill requirements (LoSr) respectively. A task allocation matrix supports the identification of possible combinations of automation and collaboration solutions for a human-centred and collaborative wire harness assembly process. System designers and integrators may utilise the design and specification methodology to identify the potential and extent of human-robot collaboration in collaborative manufacturing assembly operations.

Hybrid force-displacement-based design methods for self-centering wall structures

Self-centering wall structures (SCWs) are well-developed resilient structures and are being gradually implemented in practical engineering. The direct displacement-based design (DDBD) method is commonly adopted for the seismic design of SCWs due to its predictable displacement pattern. Due to the complexity of DDBD, practical engineers still commonly use the present force-based design (FBD) methods. However, the existing FBD method is inapplicable when the deformation of SCWs is large. To make the design procedure more acceptable to engineers and promote SCWs in real practice, three design methods were proposed: a force-based design method by empirical formula, a force-based method by iteration, and a hybrid force-displacement-based design method (HBD). The applicability of FBD by existing empirical formulas of structural periods in several codes for SCWs was discussed. In FBD by iteration, the initial prestress is iterated to determine secant stiffness and the structural period so that SCWs can be designed following its constitutive relationships. HBD is carried out by comparing the resistance of the structure under the target displacement with the earthquake demand according to the deformation mode of the SCWs. Compared with the existing DDBD methods, the proposed design methods can simplify the design process in engineering applications while keeping the design outcomes consistent with DDBD and proved to be reasonable with nonlinear time history analysis. In addition, the FBD method by empirical formula and the HBD method can be implemented in the four-level seismic fortifications currently proposed in China. The proposed methods solve the issues of the existing FBD and could be a reference for engineers to design SCWs in engineering practice.

Asynchronous event-triggered [formula omitted][formula omitted] control for 2D Markov jump systems subject to networked random packet losses

This paper investigates the issue of asynchronous event-triggered control for two-dimensional Markov jump systems subject to networked random packet losses. The asynchronous behavior between the plant and controller is characterized by a hidden Markov model, and the packet loss behavior is described by a Bernoulli stochastic process. To relieve the communication pressure, an event-triggered strategy with independent triggering behavior in the horizontal and vertical directions is given. A sufficient condition is established to ensure stochastic stability and H∞ performance for the closed-loop system. Then, a method for designing an asynchronous event-triggered controller is developed through eliminating nonlinearities formed by the inverse of Lyapunov matrices. Moreover, based on convex optimization of the H∞ performance, an algorithm is proposed to find the maximum feasible domain of the event-triggered thresholds. Finally, a Darboux equation with Markov jump properties is applied to verify the effectiveness of the presented design method.

Low-frequency magnetic microwave absorber using reactive ground for extended bandwidth

A design method to extend the operating bandwidth of a low-frequency magnetic microwave absorber is presented. According to the mapped impedance distribution from the design objective, a synthesized reactive ground consisting of a triple-ring array, instead of the perfect electric conductor (PEC), is conveniently placed at the back of a commercially available magnetic sheet to realize impedance matching. Compared with the conventional PEC, the reactive ground extends the operating bandwidth of reflection coefficient being less than −10 dB by introducing four consecutive absorption peaks so that the optimized structure achieves broadband absorption from 2.3 to 4.3 GHz with a thickness of 0.027 times the free-space wavelength at the lowest operating frequency and a 60.6% fractional bandwidth which is nearly two times that of the conventional structure. The physical mechanism is further investigated through the distributions of current flow and power loss. Finally, a prototype is fabricated and measured. The good agreement between the simulated and measured results verifies the effectiveness of the presented design method.

Improved disturbance observer-based fixed-time adaptive neural network consensus tracking for nonlinear multi-agent systems

This paper is concerned with the problem of fixed-time consensus tracking for a class of nonlinear multi-agent systems subject to unknown disturbances. Firstly, a modified fixed-time disturbance observer is devised to estimate the unknown mismatched disturbance. Secondly, a distributed fixed-time neural network control protocol is designed, in which neural network is employed to approximate the uncertain nonlinear function. Simultaneously, the technique of command filter is applied to fixed-time control, which circumvents the “explosion of complexity” problem. Under the proposed control strategy, all agents are enable to track the desired trajectory in fixed-time, and the consensus tracking error and disturbance estimation error converge to an arbitrarily small neighborhood of the origin, meanwhile, all signals in the closed-loop system remain bounded. Finally, a simulation example is provided to validate the effectiveness of the presented design method.

Design of Structural Steel Components According to Manufacturing Possibilities of the Robot-Guided DED-Arc Process

Additive manufacturing with the DED-arc process offers limited freedom in terms of the geometric shape of work pieces. The process and fabrication systems restrict the part geometry producible, which must be taken into account during design already. For this reason, a design process was investigated in which geometry generation is based on a self-organizing system. The aim of using a self-organizing system is the possibility to directly control the geometry-defining points. Next to load cases, the design method considers geometric boundary conditions from the production process when generating the geometry. In order to identify these geometrical constraints from production experimentally, a concept of Case Study Demonstrators was applied. This was used to investigate how path planning and production can be carried out for specific geometrical features and to identify restraints of the process and the manufacturing system, e.g., smallest producible wall thickness and overhangs. Subsequently, the obtained restraints were considered as boundary conditions for the design process and were included in the modification of an example geometry. By applying the presented design method, it was possible to maintain a minimum wall thickness throughout the structure while generating a topologically optimized geometry. In contrast to compliance with the minimum wall thickness, no satisfactory behavioral rule could be found for limiting the overhang.

Enhancing the Seismic Resilience of Steel Moment Resisting Frame with a New Precast Self-Centering Rocking Shear Wall System

In this paper, a new precast self-centering rocking shear wall system (PSCRSW) mainly composed of precast reinforced concrete (RC) wall, V-shaped steel brace and pre-pressed disc spring friction damper (PDSFD) are proposed to enhance the seismic resilience of steel moment resisting frame (SMRF). The mechanical behavior of PDSFD was investigated and simulated. The skeleton model of PSCRSW was theoretically derived and numerically validated, and the hysteretic performance under different design parameters was discussed and compared with that of the conventional RC shear wall. Based on the analyses, design principles and suggestions for PSCRSW were given. Then, an efficient seismic resilient design method for enhancement of SMRF was proposed, which considers performance objectives of multiple seismic hazard levels and has less design iteration. A typical SMRF was adopted as the prototype to be enhanced by the presented PSCRSW and design method. Reliable numerical models for the prototype and the enhanced SMRF were established, and nonlinear dynamic analyses were performed to assess the effectiveness of enhancing strategy. The results show that PSCRSW can realize approximate yielding behavior, displacement capacity and lateral strength to the conventional shear wall and can significantly lower the residual drift and wall damage. During the design, the ratio of preload to friction force for PSCRSW was suggested to be 1.5~2.0, and the bearing capacity for the wall was suggested to be amplified 1.2 times. Thereby, desirable bearing and self-centering performances can be guaranteed. The presented design method is capable of achieving the inter-story drift ratio targets and the expected roof drift ratios simultaneously, and the seismic resilience of the chosen SMRF was significantly improved by a large margin of reduction in residual inter-story drift and frame member damages.

Design of marine propellers with prescribed and optimal spanwise circulation distributions based on genetic algorithms and neural network

Lifting-surface design methods are proposed for marine propellers based on genetic algorithms (GAs) and a two-layer back-propagation neural network (BPNN). For propellers with prescribed spanwise circulation distributions, the design problem is solved as GA-based optimization of camber surface geometry and pitch distribution which produce a circulation distribution to best fit the prescribed one. An in-house code based on the vortex lattice method (VLM) is employed to simulate circulation distribution and hydrodynamic performance of the propeller. Computer codes are developed in this research based on existing genetic algorithms, with a measure devised to accelerate convergence and improve the quality of solution. To optimize the spanwise circulation distribution, GAs are utilized again to explore the BPNN model established via the MATLAB toolbox and the in-house VLM code. Then the optimal circulation distribution is taken as the prescribed one for the GA-based design method mentioned above. Numerical tests are conducted to determine proper ranges of modeling parameters, such as the population size for GAs and the number of vortex lattices, and to assess the performance of the BPNN established. To numerically validate the proposed methods, viscous-flow simulation by solving the Reynolds-averaged Navier-Stokes equations is carried out for the propeller designed by using both methods mentioned above. The predicted pressure distributions over blade surfaces correlate consistently with the circulation distributions used to design the propeller, thus indicating that present design methods are effective and reasonably accurate.

Soil expansion acting within geosynthetic-reinforced embankment over sinkhole

The appearance of sinkholes which may not be accurately observed is one of the main problems that caused the stability of construction. Among geotechnical solutions, the geosynthetic-reinforced embankment has been commonly applied due to a variety of benefits. Numerous studies have recently improved the knowledge of the complicated mechanisms acting inside the reinforcement system once a cavity appears. Many present design methods have been established to propose the necessary parameters to apply the technic to potential areas that are prone to subsidence. However, there are many calculated hypotheses based on simple assumptions that may cause the actual effect of the design including the soil expansion inside the embankment. A numerical model has been developed in the present study by using the finite element method and the soil expansion is the main objective to investigate. Considering the deformation, axial forces, and stress applied to the geosynthetics, the expansion factor is determined by two methods and it is confirmed not to be a global and uniform phenomenon.

Design method for zoom systems based on tunable lenses

It is well known that tunable lenses, with refractive power that can be varied, e.g., by changing the curvature of a membrane, can replace the motion of lens groups in zoom systems. Similar to classical zoom systems, the performance of these systems is heavily influenced by the fundamental first-order layout. Moreover, the first-order layout sets the most important requirements for the employed tunable lenses. In this contribution, we present a method for the analysis of a large number of possible first-order solutions for typical requirements and for the selection of the most promising layouts. The first-order solution space is mapped, allowing the layouts to be automatically filtered and plotted depending on pre-defined characteristics. Ray tracing of the marginal and chief rays combined with the traditional thin lens aberration theory provide efficient estimations of the expected installation space requirements and performance for each first-order layout. Using an example, we demonstrate good agreement between these estimations and the corresponding real lens layout, optimized by commercial raytracing software. The presented design method for zoom systems based on tunable lenses is compared with similar approaches for classical zoom lenses.

Building blocks of a flip-chip integrated superconducting quantum processor

We have integrated single and coupled superconducting transmon qubits into flip-chip modules. Each module consists of two chips—one quantum chip and one control chip—that are bump-bonded together. We demonstrate time-averaged coherence times exceeding 90 μs, single-qubit gate fidelities exceeding 99.9%, and two-qubit gate fidelities above 98.6%. We also present device design methods and discuss the sensitivity of device parameters to variation in interchip spacing. Notably, the additional flip-chip fabrication steps do not degrade the qubit performance compared to our baseline state-of-the-art in single-chip, planar circuits. This integration technique can be extended to the realisation of quantum processors accommodating hundreds of qubits in one module as it offers adequate input/output wiring access to all qubits and couplers.

A General Design Method of Cam Profile Based on Cubic Splines and Dynamic Model: Case Study of a Gravity-Driven Tricycle

This paper proposes a general design method for cams based on the kinematics and dynamics of a mechanical system. According to the actuator’s trajectory, the cam profile is generated in reverse based on the kinematic model of the system. Firstly, the cam design’s optimising problem is converted into the execution trajectory’s optimisation to obtain the optimum operation trajectory according to the actuator’s requirements. Secondly, the relationship between the cam profile and the actuation trajectory is modelled based on the kinematics and dynamics of the mechanical system. Then, applying the cubic spline interpolation method, the cam profile is generated, and the error compensation methods are illustrated through numerical analysis. Finally, the validity of the presented design method is verified through experiments, which demonstrate the reliability of this method.

Performance Evaluation and Design Method of Lifting-Wing Multicopters

As a novel VTOL unmanned aerial vehicle, lifting-wing multicopter with simple structure, good stability and longer flight range has been unveiled to be in service. But how to make range as long as possible to realize its potential advantages is one of the key issues in the practical application of lifting-wing multicopter. Thus, this study aims to propose a range and transition time performance evaluation to realize a sizing optimization design method for the lifting-wing multicopter. First, the dynamic model and the propulsion system model are established. Based on these models, evaluation methods for range and transition time performance are obtained with the consideration of mounting angle. Second, the influences of the main parameters on range performance are studied to offer references for design. Then, an explicit design process is proposed. Finally, a prototype is implemented, and flight experiments are performed to verify the evaluation and design method. The results indicate that the performance evaluation method has enough accuracy and suggest that it is possible to design a lifting-wing multicopter using the presented design method.