Reconfiguration Mechanism Research Articles

System Level Modeling and Control Design of hTetrakis–A Polyiamond Inspired Self-Reconfigurable Floor Tiling Robot

Fixed morphology cleaning robots mostly face significant challenges in cleaning the narrow spaces in the environment. To overcome this, a new class of self-reconfigurable floor cleaning robot, hTetrakis, made of four triangular blocks, is built. This paper focuses on the modeling and controller design of the locomotion and reconfiguration mechanism of the platform. The locomotion of the platform with respect to the velocity of the wheels is formulated based on the kinematic analysis. By modeling the system in Simscape multibody toolbox of Matlab, the maneuverability of the platform is studied. The reconfiguration of the platform is studied based on the dynamics of individual block about the hinged joint. The control architecture of this platform has two distinct Proportional-Integral-Derivative (PID) controllers to eliminate the position error during reconfiguration, and to maintain the platform’s velocity. The coverage path planning of the platform is based on the classical Travelling Salesman Problem which finds the optimal sequence of waypoints as per the minimal energy consumption. Real time experiments are carried out to validate the effectiveness of the proposed control schemes in terms of eliminating the velocity errors, and maintaining the desired trajectory.

Fluidically Reconfigurable MIMO Antenna With Pattern Diversity for Sub-6-GHz 5G Relay Node Applications

A four-element frequency reconfigurable and pattern diverse multiple-input–multiple-output (MIMO) antenna array for fifth-generation relay node applications is presented to operate in LTE bands 42 (3400–3600 MHz), 43 (3600–3800 MHz), and 46 (5150–5925 MHz). A planar microstrip line-fed monopole antenna is utilized as the MIMO element. The antenna relies on fluidic reconfiguration mechanism to either serve LTE bands 42/43 or 46. It incorporates a substrate milled channel beneath each monopole arm to hold distilled water. The water in the channel perturbs the $E$ -field distribution in the vicinity of the antenna arm and modifies the effective permittivity of the dielectric medium. To realize pattern diversity, adjacent elements are placed orthogonal to each other. Measured prototype exhibits a total active reflection coefficient $|{\text{TARC}}|$ and $|S_{11} |\leq -10$ dB for the high band when the channel is vacant (case 1) and the low band when filled with water (case 2), while minimum isolation is above 19.6 dB. The peak measured gain is ~4.6 and ~2.8 dBi, while the worst case envelope correlation coefficient (ECC) is ~0.004 and ~0.016 for cases 1 and 2, respectively. It measures 82.4 $\times$ 82.4 mm2 and was fabricated on a 1.52-mm-thick substrate of $\epsilon_{r}$ = 3.55.

Towards deterministic FPGA reconfiguration

Rigid partitioning of components in hardware/software co-design flows can lead to suboptimal choices in embedded systems with dynamic runtime requirements. FPGAs allow systems to cope with such unforeseen conditions by changing portions of hardware dynamically while other parts are still active. Nevertheless, to guarantee a transparent reconfiguration, it is necessary to ensure that it does not disrupt the timing requirements of the running tasks and vice-versa. This work proposes a deterministic FPGA reconfiguration mechanism capable of mitigating the interference generated by I/O operations occurring in parallel. The reconfiguration is confined in the idle time without interfering with or being interfered by other activities occurring in the system, including peripherals performing I/O. The scheme decomposes the reconfiguration process in small steps such that it is preemptable, and compliant with timing requirements. To quantify the impact of I/O interference on FPGA reconfiguration, we measured the execution time to load bitstreams from memory to the FPGA reconfiguration interface with multiple peripherals performing I/O in parallel. Results show that if the I/O interference is not taken into account and mitigated, the reconfiguration time can grow up to 8,800% when peripherals are performing I/O operations through DMA.

TRIZ and AHP in Early Design Stage of a Novel Reconfigurable Wheelchair

The Reconfigurable wheelchair incorporated with sit-to-stand and sit-to-sleep capabilities is the technological solution for extensive wheelchair users to promote their quality of life (QoL), safety and comfort. This paper presents the conceptual design of a reconfigurable wheelchair using the TRIZ and AHP integrated approach. The objective of this study was to develop optimal conceptual designs of a reconfigurable wheelchair by overcoming identified design conflicts. The TRIZ contradiction toolkit was employed in the early conceptual design phase. Based on the TRIZ inventive principles and developed design strategy, new reconfigurable wheelchair mechanism was modelled in SolidWorks environment, using a top-down modelling approach. Dimensions of a wheelchair were kept within the dimensions of a standard wheelchair. The newly modelled mechanism was refined using motion simulation capabilities of the SolidWorks software. The new mechanism was further integrated with different wheelchair design features by means of the morphological chart in order to get innovative conceptual designs. Further, Analytical Hierarchy Process (AHP) was utilized as a multi-criteria decision making technique for optimal conceptual design selection. Conceptual design-I (joystick controller with electric drive) received highest weight among all conceptual designs, hence selected as the optimal conceptual design. Consistency ratio (CR) for the pair-wise comparisons made throughout the AHP method was found less than 0.10. All AHP calculations were supported by Microsoft Excel Add-in for multi-criteria decision problems. For the purpose of functionality testing of newly modelled wheelchair, 3D printed wheelchair parts have been fabricated (using ABS material) and tested for desired mechanical movements. The methodology implemented in the present work can be utilized for upcoming applications in design of new assistive devices.

El lenguaje de los otros, escenario de alteridades: Aportes a la aproximación teórica entre antropología y literatura

El lenguaje, en su multiplicidad de acción como mecanismo de reconfiguración simbólica, se presenta como un elemento constante en las relaciones sociales. En este sentido la antropología se ha preguntado no sólo por la utilidad del lenguaje en estas relaciones, sino por la forma en la cual este se utiliza dentro de los análisis antropológicos y sus implicaciones metodológicas. La literatura, por su parte, se muestra como un espacio en el que el uso del lenguaje responde principalmente a un ejercicio descriptivo, que trasmuta en la articulación de distintos conceptos simbólicos para la creación de una realidad en la que el autor es el artífice, lo cual crea relaciones entre la realidad simbólica del autor literario y los conceptos abstraídos que representan la organización simbólica de sociedades específicas. Este artículo de revisión busca explorar, a través del uso de las crónicas antropológicas y de textos literarios de ficción, las relaciones entre la antropología y la literatura desde la perspectiva del lenguaje como elemento de creación de alteridad, para proponer aproximaciones teóricas que cuestionen la relación entre el autor y el sujeto observado que, en consecuencia, se presenten como posibilidades de posturas metodológicas en las cuales se haga uso del lenguaje como herramienta analítica.

Research on the Structural Rigidity Characteristics of a\xa0Reconfigurable TBM Thrust Mechanism

To improve the adaptability of TBMs in diverse geological environments, this paper proposes a reconfigurable Type-V thrust mechanism (V-TM) with rearrangeable working states, in which structural stiffness can be automatically altered during operation. Therefore, millions of configurations can be obtained, and thousands of instances of working status per configuration can be set respectively. Nonetheless, the complexity of configurations and diversity of working states contributes to further complications for the structural stiffness algorithm. This results in challenges such as difficulty calculating the payload compliance index and the environment adaptability index. To solve this problem, we use the configuration matrix to describe the relationship between propelling jacks under reconfiguration and adopt pattern vectors to describe the working state of each hydraulic cylinder. Then, both the dynamic compatible equation between propeller forces of the hydraulic cylinders and driving forces, and the kinematic harmonizing equation between the hydraulic cylinder displacements and their deformations are established. Next, we derive the stiffness analytical equation using Hooke’s law and the Jacobian Matrix. The proposed approach provides an effective algorithm to support structural rigidity analysis, and lays a solid theoretical foundation for calculating the performance indexes of the V-TM. We then analyze the rigidity characteristics of typical configurations under different working states, and obtain the main factors affecting structural stiffness of the V-TM. The results show the deviation degree of structural parameters in hydraulic cylinders within the same group, and the working status of propelling jacks. Finally, our constructive conclusions contribute valuable information for matching and optimization by drawing on the factors that affect the structural rigidity of the V-TM.

A methodology to achieve the set of operation modes of reconfigurable parallel manipulators

The demand for increasingly more versatile machinery has boosted the development of the so-called reconfigurable mechanisms. In this paper, the authors present a general methodology to assess the multioperational capacity of a 6-DOF parallel manipulator basing on the possible motion patterns having Lie group structure that the manipulator owns. This ability of having different operation modes enables the manipulator to adapt to diverse tasks. To show the potential of the methodology, this approach has been applied to the 6-DOF 3-CPCR which is capable of generating multiple motion patterns. In addition to carrying out the complete theoretical study in which all the different operation modes are obtained, and validating the procedure with GIM software designed for kinematic analysis and design of mechanisms, a demonstration prototype of the 3-CPCR parallel manipulator has been also built.

Lie Group Based Type Synthesis Using Transformation Configuration Space for Reconfigurable Parallel Mechanisms With Bifurcation Between Spherical Motion and Planar Motion

Abstract This paper investigates novel reconfigurable parallel mechanisms with bifurcation between planar subgroup SE(2) and rotation subgroup SO(3) based on a transformation configuration space. Having recollected necessary theoretical fundamentals with regard to compositional submanifolds and kinematic bonds, the motion representation of the platform of reconfigurable parallel mechanisms are investigated. The transformation configuration space of a reconfigurable parallel mechanism with motion branches is proposed with respect to the fact that the intersection of Lie subgroups or submanifolds is the identity element or a non-identity element. The switch conditions of the transformation configuration space are discussed, leading to establishment of a theoretical foundation for realizing a switch of motion branches. The switch principle of reconfigurable parallel mechanisms is further investigated with respect to the common motion between SE(2) parallel-mechanism motion generators and SO(3) parallel-mechanism motion generators. Under this principle, the subchains with common motion generators are synthesized and divided into two types of generators. The first type of generators generates kinematic chains with a common intersection of three joint axes, and the second type of generators generates a common intersection of two joint axes. Following this, two types of reconfigurable parallel mechanisms with three identical subchains are synthesized, resulting in 11 varieties in which platforms can be switched between SE(2) and SO(3) after passing through the singularity configuration space.

A Reconfigurable Method for Intelligent Manufacturing Based on Industrial Cloud and Edge Intelligence

The development of Industry 4.0 has provided the possibility to meet frequent changes in product type and batches, a sharp decline in the delivery cycle, constraints of quality cost, and other relevant parameters of customized production mode. Intelligent manufacturing, as a core of Industry 4.0, represents a deep integration of new IT technologies, such as the industrial Internet of Things and service-oriented architecture, and manufacturing process. To realize intelligent manufacturing, this article introduces a cloud-assisted and edge-decision-making manufacturing architecture that contains a cloud and production edges. An intelligent production edge is designed to provide the traditional devices the abilities of data access and self-decision making. Besides, the proposed architecture is modeled as a multiagent system with the edge intelligence support, describing the agent-based reconfiguration mechanism from the three aspects, namely, agent interaction, agent behavior, and negotiation mechanism. The experimental results show that the reconfigurable method based on the proposed architecture can be used in the mixed-flow production scenario based on random orders, to improve the adaptability and robustness.

Reconfigurable machine tools: a perspective

Short life cycle of the products, large product variants and unanticipated changes in customer demand in a dynamic social context pose a significant challenge for design of an appropriate manufacturing system. Reconfigurable machine tool, which is the foundation block for reconfigurable manufacturing system is envisaged as a solution that caters to the current market forces. This paper discusses the reconfiguration mechanisms, which enable transformation of conventional machine tools, such as, drilling, lathe and milling machines into reconfigurable machines that will achieve the objectives. It is expected that, this work will help designers and practicing engineers by making them aware of the reconfiguration mechanisms, which have become a necessity for the very survival of the manufacturing sector by lowering the overall capital costs and, therefore, the per unit fixed costs.

Design and Development of a Reconfigurable Screw-wheeled Omnidirectional Mobile Robot

Omnidirectional mobility plays an important role for mobile robots to provide flexibility in their motion. However, most of the existing omnidirectional mechanisms are only superior in indoor applications, but inappropriate for outdoor purposes. This paper introduces the design and development of an omnidirectional mobile robot with reconfigurable screw-wheeled mechanism. The orientation of the screw wheels is adjustable in order to enable flexibility in traction control to provide more propulsion drive in certain conditions. The experimental results are given to demonstrate the performance of the omnidirectional mobile robot on different ground surfaces and different wheel’s orientation.

Frequency and impedance reconfigurable antenna using magnetically-actuated low-loss Ferrofluid loads

ABSTRACTWith space and spectrum at a premium, antennas must be capable of operating well across a variety of frequencies and environments. This work presents a novel method of frequency and impedance reconfiguration through the actuation of a ferrofluid load with a permanent magnetic bias field, while still achieving up to 85% efficiency. Under a sufficiently strong bias field, the ferrofluid load behaves as a low-loss movable dielectric load, and the actuation method avoids the complexity associated with microfluidic pumps and DC bias networks. This work opens a new field of reconfiguration mechanisms for antennas through magnetic repositioning of low-loss ferrofluid loads.

Influence of Link Lengths & Input Angles on the Foot Locus Trajectory of Klann Mechanism

Locomotive drive mechanisms for robots have been an active research area in the field mobile robotics. Several drive mechanisms such as wheeled, legged, hybrid & reconfigurable mechanisms have been extensively studied. The legged locomotive drive mechanism has several advantages to its credit & it is often bio-inspired. The disadvantage of legged locomotive drive mechanism in general is it is often considered as complex in design due to its multi degrees of freedom which requires complex control scheme. This has led roboticists to explore minimal legged locomotive drive mechanisms consisting of single degrees of freedom. The present work focuses on synthesis and analysis of one such planar mechanism such as klann mechanism for a mobile robot application. In this work, we have synthesized the various linkages of klann mechanism to find the optimal foot locus trajectory. The synthesis and analysis of mechanism is performed using SAM (Synthesis and analysis of mechanism) software. We have described influence of various parameters such linkage length and input crank angle on the foot locus. We have compared the foot locus trajectory for three different foot locus by performing the kinematic analysis. Various parameters such as position, velocity and acceleration of linkages are compared & illustrated in detail. The information provided in this work will help the roboticists to select appropriate link length for klann mechanism to obtain various foot locus designs. This information may be further used to design efficient legged locomotive drive mechanisms for various terrain conditions.

Rational Design of pH-Responsive DNA Motifs with General Sequence Compatibility.

Reconfigurable molecular events are key to molecular machines. In response to external cues, molecular machines rearrange/change their structures to perform certain functions. Such machines exist in nature, for example cell surface receptors, and have been artificially engineered. To be able to build sophisticated and efficient molecular machines for an increasing range of applications, constant efforts have been devoted to developing new mechanisms of controllable structural reconfiguration. Herein, we report a general design principle for pH-responsive DNA motifs for general DNA sequences (not limited to triplex or i-motif forming sequences). We have thoroughly characterized such DNA motifs by polyacrylamide gel electrophoresis (PAGE) and fluorescence spectroscopy and demonstrated their applications in dynamic DNA nanotechnology. We expect that it will greatly facilitate the development of DNA nanomachines, biosensing/bioimaging, drug delivery, etc.

Rational Design of pH‐Responsive DNA Motifs with General Sequence Compatibility

AbstractReconfigurable molecular events are key to molecular machines. In response to external cues, molecular machines rearrange/change their structures to perform certain functions. Such machines exist in nature, for example cell surface receptors, and have been artificially engineered. To be able to build sophisticated and efficient molecular machines for an increasing range of applications, constant efforts have been devoted to developing new mechanisms of controllable structural reconfiguration. Herein, we report a general design principle for pH‐responsive DNA motifs for general DNA sequences (not limited to triplex or i‐motif forming sequences). We have thoroughly characterized such DNA motifs by polyacrylamide gel electrophoresis (PAGE) and fluorescence spectroscopy and demonstrated their applications in dynamic DNA nanotechnology. We expect that it will greatly facilitate the development of DNA nanomachines, biosensing/bioimaging, drug delivery, etc.

Varactor Loaded Pattern Reconfigurable Patch Antenna With Shorting Pins

A varactor loaded pattern reconfigurable patch antenna with shorting pins is presented. Continuous beam reconfigurability and null scanning are realized by introducing two sets of shorting pins and only four varactors into a square patch antenna. For this antenna, the edge-shorting pins are placed along with the parallel edges of the square patch for different $E$ -fields. Another set of shorting pins are fixed symmetrically along the diagonal of the square patch for directivity and null depth enhancement. To achieve continuous pattern reconfiguration, varactors are connected with the edge-shorting pins to provide continuously tunable phase difference. The mechanism of the pattern reconfiguration and effects of the shorting pins are discussed based on a transmission-line model. The proposed antenna has a compact size of $0.4\,\,\lambda _{0} \times 0.4\,\,\lambda _{0} \times 0.06\,\,\lambda _{0}$ . Both the simulated and measured results confirm that the proposed antenna has the capabilities of beam steering and null scanning. The measured main beam scans from −55°to −15.5°and 19° to 54°, with a gain reduction of 3.22 dB relative to maximum (7.55 dBi). Meanwhile, the coverage of radiation pattern null is from −74° to 62°.

Fragmentation-avoiding spectrum assignment algorithm based on time-spectrum partition for elastic optical networks

Abstract In order to address the fragmentation problem in the time domain and the spectrum domain in elastic optical networks, a fragmentation-avoiding spectrum assignment algorithm based on time-spectrum partition (FASA-TSP) is proposed. Firstly, a time-spectrum partition method, splitting whole optical spectrum into several spectrum partitions and then split every spectrum partition into multiple time-spectrum partitions, is proposed. On the basis of this, a spectrum assignment policy is proposed, where each time-spectrum partition is first used to transmit requests with the same rate and the closest holding time. Besides, each spectrum partition is executed last-fit policy to search available spectrum resources when requests with the same rate are not successfully transmitted in dedicated time-spectrum partition. Lastly, other spectrum partitions are used to search available spectrum resources when there are no available spectrum resources in dedicated spectrum partition. Meanwhile, when there is only one available spectrum partition, execute last-fit policy. When there are several available spectrum partitions, we design a partition selection equation to minimize spectrum collision. Moreover, a spectrum collision avoidance reconfiguration mechanism, moving requests that are not transmitted in their dedicated time-spectrum partition to their dedicated time-spectrum partition, is also proposed. Simulation results show that the FASA-TSP algorithm can effectively reduce the bandwidth blocking probability and improve spectrum utilization ratio.

A novel 6R metamorphic mechanism with eight motion branches and multiple furcation points

The furcation point in a mechanism is a salient feature of reconfigurable mechanisms and change of a joint from an unconstrained condition to a geometrically constrained condition resulting in naturally link annexing with this geometrical constraint is a typical feature of metamorphic mechanisms. This paper presents a novel 6R metamorphic mechanism by inserting two revolute joints to a Bennett mechanism. From parameters of this novel 6R metamorphic mechanism, the source mechanism before changing is a special case of the Bricard 6R line-symmetric mechanism while the closure equation gives constraint conditions of joints. The geometrically constrained conditions result in variable motion branches of the mechanism. When all joints are unconstrained geometrically, two 6R motion branches can be obtained and when two joints are under geometric constrained, three 4R motion branches can be obtained. Further, three further motion branches with coaxial joints are obtained and motion branch transformation is illustrated with kinematic curves. For each of the motion branches, motion screws of this novel 6R metamorphic mechanism present corresponding geometry morphology and are analysed with screw algebra.

Kinematic Optimization of a Reconfigurable Spherical Parallel Mechanism for Robotic-Assisted Craniotomy

Abstract The craniotomy is a surgical task that is required to allow access to the patient's brain. It consists of using neurosurgical drills to open a path through the skull. The high risk resulting from human dexterous limit justifies the use of an accurate robotic system to perform craniotomy. The present work introduces the kinematic design of a mechanism for a robotic manipulator dedicated to craniotomy. Motion capture experiments have been carried out to measure the motion of a surgical drill during the execution of craniotomy on human cadavers. The results of the experiments are discussed. As this medical application requires a remote center of motion (RCM), a new type of 3-RRR spherical parallel mechanism (SPM) is proposed to manipulate the surgical drill. The novelty of this mechanism is the integration of a reconfigurable base that re-orients the first revolute joint of the RRR legs. A mechanical architecture concept is introduced to implement this reconfiguration. It is made of three pantographic linkages that manipulate the base of the SPM. The kinematics of the new mechanism is analyzed. The influence of this reconfigurable parameter is studied on two different aspects: the mechanism workspace and kinematic performances. Based on these kinematic data, the optimization of a mechanism is performed. The drill motion trajectories are used to evaluate the behavior of the optimized mechanism. It is finally compared to the classical SPM with a trihedral base, showing the contribution of the new reconfiguration variable on the mechanism dexterity.

Flow-seaweed interactions of Saccharina latissima at a blade scale: turbulence, drag force, and blade dynamics

Physical interactions between seaweed blades of Saccharina latissima and unidirectional turbulent flow were examined in an open-channel flume, focussing on flow velocities, drag force acting on a blade, and blade reconfiguration. The data reveal that seaweed blades adjust to high-energy flow conditions relatively quickly, efficiently reducing flow-induced drag via compaction, a mechanism of blade reconfiguration. The drag coefficient of blades of S. latissima varied between 0.02 and 0.07 over a range of mean flow velocities from 0.1 to 0.55 m/s. Both flow action and blade biomechanical characteristics influenced the blade dynamics, with the flow role being predominant in highly energetic conditions. The interaction mechanisms and their strength were found to be scale-dependent, with the combined effect of reduced mean flow velocity and enhanced turbulence in blade wakes. The thickness of the diffusive boundary layer, an important factor in nutrient uptake from the surrounding water, was estimated to be in the range from 0.010 to 0.067 mm. Mechanisms of blade adjustment to the flow and scale-dependent dynamic interactions between blades and turbulent eddies have direct implications for seaweed growth, acclimation, and survival. The estimates of the drag coefficient and the thickness of the diffusive boundary layer will be useful for the development of bio-physical models, environmental assessments, and design of seaweed farms.