Foldable Mechanism Research Articles

Portable Photovoltaic Power Generation System for Applications along the Railway and Its Improved Efficiency by Automatic Dust Removal by Foldable Solar Energy Collector

To meet the demands of power supply for applications along the railway in treacherous terrain, this article proposes a portable photovoltaic power generation system (PVPGS) based on a foldable mechanism for applications along the railway. First, the designed system mainly consists of a foldable solar energy collector (FSEC) and an energy conduit. Dust deposited on the photovoltaic panels is reduced while the FSEC is being folded or unfolded. Moreover, the characteristics of dust particles, effects of natural dust on photovoltaic glass transmittance, and power of portable PVPGS are investigated. In addition, the mechanism on improving the power generation efficiency of PVPGS is analyzed. The results demonstrate that the designed foldable mechanism can contain the dust deposition on photovoltaic power loss within 4%. Finally, Chengdu city and Sichuan–Tibet Railway are selected for an application prospect, and the results show that the average annual power generation of one portable PVPGS can reach up to 16.7 kWh, which is enough to power sensors and other applications along the railway. Simulations, theoretical analyses, and experiments confirm the feasibility of using the proposed portable PVPGS to power applications along the railway.

A Deployable Wideband Differential-Fed Dual-Polarized Patch Antenna Array

In this paper, a deployable wideband differential-fed dual-polarized high-isolation patch antenna array is proposed. To achieve dual polarization, every element has two pairs of differential ports. Because of the differential design, the couplings from the adjacent ports (the other pair of ports) are canceled and high isolation between the two polarization is achieved. In addition, capacitive feeds are applied to enhance the bandwidth. By integrating with two planar Marchand baluns, the two pairs of the differential ports are excited for dual polarization. Then, the wideband dual-polarization patch antenna element is expanded to a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4\times 4$ </tex-math></inline-formula> antenna array for better gain. In order to achieve deployment, we present a novel foldable mechanism suitable for low-frequency patch antenna array, which is different from the conventional design on the flexible printed board. The deployment concept is presented. One prototype is fabricated and measured. Its operating band is from 1.15 GHz to 1.35 GHz. The peak gains of the two polarizations are 14.4 dBi and 14.1 dBi respectively.

Rigid-Foldable Mechanism Inspired by Origami Twisted Tower

Abstract Rigid origami mechanisms have great practical utility in different fields. This paper presents a rigid and foldable mechanism based on the origami artwork Twisted Tower. The mathematical model of the funnel-shaped tower cell was developed for the first time, which accurately describes its kinematic behavior. Based on this model, criteria for the appropriate geometry of the tower components are proposed to prevent internal interference in the tower mechanism during the twisting movement. In this paper, two geometric design cases of twisted tower mechanisms, including a normal-shaped tower and a heteromorphic tower, are presented. Several additional modifications were also imposed to adapt the proposed mechanism to generalized and standardized manufacturing and assembly. Experimental results illustrate that the kinematic characteristics of the fabricated mechanism meet its designed performance. Furthermore, the proposed mechanism is suitable for applications such as continuum manipulators, which exhibit much better resistance to external loads than their flexible-rigid hybrid counterparts.

Towards Rapid Prototyping of Foldable Graphical User Interfaces with Flecto

Whilst new patents and announcements advertise the technical availability of foldable displays, which are capable to be folded to some extent, there is still a lack of fundamental and applied understanding of how to model, to design, and to prototype graphical user interfaces for these devices before actually implementing them. Without waiting for their off-the-shelf availability and without being tied to any physical foldable mechanism, Flecto defines a model, an associated notation, and a supporting software for prototyping graphical user interfaces running on foldable displays, such as foldable smartphone or assemblies of foldable surfaces. For this purpose, we use an extended notation of the Yoshizawa-Randlett diagramming system, used to describe the folds of origami models, to characterize a foldable display and define possible interactive actions based on its folding operations. A guiding method for rapidly prototyping foldable user interfaces is devised and supported by Flecto, a design environment where foldable user interfaces are simulated in 3D environment instead of in physical reality. We report on a case study to demonstrate Flecto in action and we gather the feedback from users on Flecto, using Microsoft Product Reaction Cards.

Analysis of a novel six-degree of freedom foldable parallel mechanism with optimized under-balance springs

The capacities of parallel mechanisms are limited by their height for the narrow space applications, such as the shipboard stability platforms, household simulators, aerospace mechanisms, etc. This paper proposes a novel foldable six-DOF parallel manipulator which has three main limbs with each actuated by two actuators. With the ability to fold in the vertical direction, this mechanism can be deployed from a height of about 0.278 m to 2.218 m, and the required driving stroke is only 0.67 m by the analysis results of the workspaces. However, this stroke enlargement leads to large driving forces. In order to improve the capacity for the heavy loading of this foldable mechanism, each leg is assisted by a balance spring. Static and dynamics models are built for the calculation of the driving forces and constraint forces. Two methods to calculate the optimal balance force for objective driving force are also proposed and based on the designed trace in the workspace, the springs’ linear stiffness is optimized. The simulation results demonstrate that the actuators’ driving forces are much reduced, and the homogeneity between the fully folded and deployed configuration is much improved by adding balance springs.

A High‐Efficiency, Portable, Solar‐Powered Cooling System Based on a Foldable‐Flower Mechanism and Wireless Power Transfer Technology for Vehicle Cabins

In summer, the high temperature inside vehicles is a problem, because cooling a vehicle parked under the scorching sun is both time and energy consuming. Herein, a portable solar‐powered cooling system (SPCS) is proposed based on a foldable‐flower mechanism and wireless power transfer (WPT) technology. The proposed system consists of three main parts: a solar foldable‐flower module (SFFM), an energy transfer module, and a temperature control module. The SFFM is a novel foldable mechanism that achieves a high space utilization through a rotating process and a folding process, like a flower opening its petals. The SFFM, equipped with photovoltaic (PV) cells, collects solar energy and converts it into electricity. The energy transfer module stores electricity from the SFFM in a supercapacitor via a WPT unit. The temperature control module achieves automatic temperature regulation using a cooling device. Experimental results show that output power reaches up to 7.571 W with a load resistor of 5 Ω, whereas the efficiency of the WPT reaches up to 73.6% with a load resistor of 15 Ω. Moreover, thermal simulation results illustrate that the proposed system achieves an average temperature reduction of 27.45 °C, making it feasible and effective to cool a hot vehicle cabin.

A New Butterfly-Inspired Compliant Joint with 3-DOF In-plane Motion

This paper proposes a new butterfly-inspired compliant joint by combining a butterfly’s profile and a foldable mechanism. The joint can achieve three degrees of freedom in its fabrication plane, including two translations in the x- and y-axes and a rotary motion around the z-axis. Equivalent spring stiffness of the joint is easy to be adjusted by adopting a foldable mechanism, while a butterfly’s profile gives better compliance. Closed-form model of the joint is established to calculate stiffness, displacement, and rotational angle. Performances and effectiveness of the proposed joint are verified by comparing with other joints. A prototype is fabricated, and experiments are conducted. The results show a good agreement between the analytical model, simulation, and experiment. Compared with a conventional rectangular flexure joint in terms of bending displacement and compressive displacement, the results found that performances of the joint are greatly improved. Bending displacement and angular displacement of the joint are increased by up to 14.6% and 12.6%, respectively. The proposed joint can be considered as a potential candidate for a precise positioning system.

Design and Analysis of a Scissor-bending Deployable and Foldable Mechanism

Design and Analysis of a Scissor-bending Deployable and Foldable Mechanism

An origami-inspired, self-locking robotic arm that can be folded flat.

A foldable arm is one of the practical applications of folding. It can help mobile robots and unmanned aerial vehicles (UAVs) overcome access issues by allowing them to reach into confined spaces. The origami-inspired design enables a foldable structure to be lightweight, compact, and scalable while maintaining its kinematic behavior. However, the lack of structural stiffness has been a major limitation in the practical use of origami-inspired designs. Resolving this obstacle without losing the inherent advantages of origami is a challenge. We propose a solution by implementing a simple stiffening mechanism that uses an origami principle of perpendicular folding. The simplicity of the stiffening mechanism enables an actuation system to drive shape and stiffness changes with only a single electric motor. Our results show that this design was effective for a foldable arm and allowed a UAV to perform a variety of tasks in a confined space.

A Review of Thickness-Accommodation Techniques in Origami-Inspired Engineering

Origami has served as the inspiration for a number of engineered systems. In most cases, they require nonpaper materials where material thickness is non-negligible. Foldable mechanisms based on origami-like forms present special challenges for preserving kinematics and assuring non-self-intersection when the thickness of the panels must be accommodated. Several design approaches for constructing thick origami mechanisms by beginning with a zero-thickness origami pattern and transforming it into a rigidly foldable mechanism with thick panels are reviewed. The review includes existing approaches and introduces new hybrid approaches. The approaches are compared and contrasted and their manufacturability analyzed.

A Novel Axial Foldable Mechanism for a Segmented Primary Mirror of Space Telescope

Future space missions will have larger telescopes in order to look deeper into space while improvising on spatial resolution. The primary mirrors for these telescopes will be so large that using a monolithic mirror will be nearly impossible because of the difficulties associated with its fabrication, transportation, and installation on a launch vehicle. The feasibility of launching these huge mirrors is limited because of their small launch fairing diameter. The aerodynamic shape of the fairing requires a small diameter, but the height of the launch vehicle, which is available for designers to utilize, is larger than the fairing diameter. This paper presents the development of an axial deployment mechanism based on the screw jack principle. The mechanism was designed and developed, and a prototype was constructed in order to demonstrate a lab model.

Foldable Surgical Stereo Microendoscope With Continuously Adjustable Convergence

The paper presents a new design of a stereo endoscope for minimally invasive surgery with: cameras positioned at the tip of the instrument (inside the patient), angle of convergence of the optical axes of the cameras variable continuously, and a foldable mechanism reducing the outer diameter of the endoscope to almost the diameter of the single camera in order to reduce the size of the insertion port. After the insertion the endoscope is deployed and the two cameras move side by side. A very simple compliant mechanism is used to drive the deployment and the adjustment of the convergence angle.