Design and Analysis of a Novel Reconfigurable Parallel Manipulator with Kirigami-inspired Bennett Plano-Spherical Linkages and Angular Pouch Motors

Drawing inspiration from kirigami, a creative art of papercutting, this paper first present a simple crease pattern of a kirigami model. In terms of artimimetics which bridges the origami/kirigami art and mechanisms, the kinematic equivalent, an overconstrained 6R linkage, is extracted from the kirigami model. In terms of screw theory, constraint singularity induced transitory position and distinct closed-loop motion branches of the 6R linkage is revealed. Using the Bennett plano-spherical linkage as a closed-loop subchain of kinematic limbs, this paper then introduce a new reconfigurable parallel manipulator with three hybrid kinematic limbs. Each limb of the manipulator consists of a Bennett plano-spherical linkage and a R(RR) serial chain. Using a geometric approach, the constraints exerted on the platform by the hybrid limb are explored by analysing the motion-screw systems of the equivalent serial kinematic limb corresponding to each motion branch of the closed-loop subchain. Motion characteristics in each motion branch of the parallel manipulator are revealed. Inspired by origami-folding and inflatable actuators for soft robotics, this paper further presents a new design of inflatable bending actuator for changing motion branches of reconfigurable mechanisms. The conceptual design of the actuator is verified with a prototype fabricated using adhesive fabric and further application in reconfiguring a 3D printed foldable Bennett plano-spherical linkage.

Design of Transformable Hinged Ori-Block Dissected from Cylinders and Cones

Design strategies for foldable mechanisms have been developed with inspiration from origami. In this study, we investigate a new direction that blocks are folded in a way that origami folds as the ori-blocks to generate a new type of foldable mechanisms consisting of multiple blocks. During the investigation, we propose a design approach to construct ori-blocks dissected from cylinders and cones, where “ori” is derived from the word “origami” in its original meaning as “folding”. In this way, we cut the solids into six portions and assign rotation axes to assemble the portions into movable blocks. Interestingly, this connects the Bricard classical linkages developed in 1897 to these ori-blocks with coincidence of the position and orientation of the axes when the blocks are replaced by links. The study bridges the gap between ori-blocks, origami, and mechanisms, which proposes a set of novel reconfigurable mechanisms as ori-blocks. As spatial linkages have been widely used in a broad range of technical fields, we anticipate that ori-blocks will find several potential applications owing to their kinematics in reconfigurability.

Reconfigurable Acoustic Arrays With Deployable Structure Based on a Hoberman–Miura System Synthesis

Curved surfaces are often used to radiate and focus acoustic waves. Yet, when tessellated into reconfigurable surfaces for sake of deployability needs, origami-inspired acoustic arrays may be challenging to hold into curved shape and may not retain flat foldability. On the other hand, deployable mechanisms such as the Hoberman ring are as low-dimensional as many origami tessellations and may maintain curved shape with ease due to ideal rigid bar compositions. This research explores an interface between a Hoberman ring and Miura-ori tessellation that maintain kinematic and geometric compatibility for sake of maintaining curved shapes for sound focusing. The Miura-ori facets are considered to vibrate like baffled pistons and generate acoustic waves that radiate from the ring structure. An analytical model is built to reveal the near field acoustic behavior of acoustic arrays resulting from a Hoberman–Miura system synthesis. Acoustic wave focusing capability is scrutinized and validated through proof-of-principle experiments. Studies reveal wave focusing phenomena distinct to this manifestation of the acoustic array and uncover design and operational influences on wave focusing effectiveness. The results encourage exploration of new interfaces between reconfigurable mechanisms and origami devices where low-dimensional shape change is desired.

Intelligent Modularized Reconfigurable Mechanisms for Robots: Development and Experiment

With the development of intelligent flexible manufacturing, traditional industrial manipulators with a single configuration are difficult to meet a variety of tasks. Reconfigurable robots have developed rapidly which could change their configurations and end effectors for different tasks. The reconfigurable connecting mechanism (RCM) is a core component of reconfigurable robots. In this paper, two types of intelligent modularized RCMs with light weight, high payload, and large pose (position and attitude) error tolerance are developed. One is driven by shape memory alloy (SMA) and recovery spring. It is locked by steel balls and key. The other is driven by electromagnetic coil and locked by permanent magnet and key. The locking principle, mechanical system and control system of the two RCMs are detailed introduced. Both of them meet the requirements of high precision and high payload in the industrial field. Finally, the developed RCMs are respectively integrated to a practical robot and experimented. The experiment results verified the performance of the two RCMs.

Intelligent Modularized Reconfigurable Mechanisms for Robots: Development and Experiment

With the development of intelligent flexible manufacturing, traditional industrial manipulators with a single configuration are difficult to meet a variety of tasks. Reconfigurable robots have developed rapidly which could change their configurations and end effectors for different tasks. The reconfigurable connecting mechanism (RCM) is a core component of reconfigurable robots. In this paper, two types of intelligent modularized RCMs with light weight, high payload, and large pose (position and attitude) error tolerance are developed. One is driven by shape memory alloy (SMA) and recovery spring. It is locked by steel balls and key. The other is driven by electromagnetic coil and locked by permanent magnet and key. The locking principle, mechanical system and control system of the two RCMs are detailed introduced. Both of them meet the requirements of high precision and high payload in the industrial field. Finally, the developed RCMs are respectively integrated to a practical robot and experimented. The experiment results verified the performance of the two RCMs.

Intelligent Modularized Reconfigurable Mechanisms for Robots: Development and Experiment

With the development of intelligent flexible manufacturing, traditional industrial manipulators with a single configuration are difficult to meet a variety of tasks. Reconfigurable robots have developed rapidly which could change their configurations and end effectors for different tasks. The reconfigurable connecting mechanism (RCM) is a core component of reconfigurable robots. In this paper, we developed two types of intelligent modularized RCMs with light weight, high payload, and large tolerance. One of them is driven by shape memory alloy (SMA) and recovery spring. It is locked by steel balls and key. The other is driven by electromagnetic coil and locked by permanent magnet and key. The locking principle, mechanical system and control system of the two RCMs are detailed. Both of them meet the requirements of high precision and high payload in the industrial field. Finally, the developed RCMs are respectively integrated to a practical robot and experimented. The experiment results verified the performance of the two RCMs.

Three Novel Symmetric Waldron–Bricard Metamorphic and Reconfigurable Mechanisms and Their Isomerization

This paper explores a class of metamorphic and reconfigurable linkages belonging to both Waldron's double-Bennett hybrid linkage and Bricard linkages, which include three novel symmetric Waldron–Bricard metamorphic and reconfigurable mechanisms, and further presents their three extended isomeric metamorphic linkages. The three novel Waldron–Bricard metamorphic and reconfigurable linkages are distinguished by line-symmetric, plane-symmetric, and line-plane-symmetric characteristics. The novel line-symmetric Waldron–Bricard metamorphic linkage with one Waldron motion branch and two general and three special line-symmetric Bricard motion branches is obtained by integrating two identical general Bennett loops. The novel plane-symmetric Waldron–Bricard reconfigurable linkage with two plane-symmetric motion branches is obtained by coalescing two equilateral Bennett loops. The novel line-plane-symmetric Waldron–Bricard metamorphic linkage with six motion branches is obtained by blending two identical equilateral Bennett loops, including the plane-symmetric Waldron motion branch, the line-plane-symmetric Bricard motion branch, the spherical 4R motion branch, and three special line-symmetric Bricard motion branches. With the isomerization that changes a mechanism structure but keeps all links and joints, each of the three novel Waldron–Bricard linkages results in an extended isomeric metamorphic linkage. This further evolves into the study of the three isomeric mechanisms. The study of these three novel metamorphic and reconfigurable mechanisms and their isomerization are carried out to demonstrate the characteristics of bifurcation and to reveal motion-branch transformation. Furthermore, by exploring the intersection of given motion branches and using the method of isomerization, more metamorphic and reconfigurable linkages can be discovered to usefully deal with transitions among possible submotions.

First- and Second-Order Kinematics-Based Constraint System Analysis and Reconfiguration Identification for the Queer-Square Mechanism

Reconfiguration identification of a mechanism is essential in design and analysis of reconfigurable mechanisms. However, reconfiguration identification of a multiloop reconfigurable mechanism is still a challenge. This paper establishes the first- and second-order kinematic model in the queer-square mechanism to obtain the constraint system by using the sequential operation of the Lie bracket in a bilinear form. Introducing a bilinear form to reduce the complexity of first- and second-order constraints, the constraint system with first- and second-order kinematics of the queer-square mechanism is attained in a simplified form. By obtaining the solutions of the constraint system, six motion branches of the queer-square mechanism are identified and their corresponding geometric conditions are presented. Moreover, the initial configuration space of the mechanism is obtained.

Reconfigurable Trusses of Nonlinear Morphing Elements

Reconfigurable mechanisms are capable of changing their behavior during operation and perform different tasks through changes of their configuration. A compliant, multistable, reconfigurable mechanism is introduced which consists of nonlinear morphing elements assembled in a truss-like configuration. These constituent elements are made of composite strips assembled to form a double-helix and exhibit tailorable nonlinear stiffness characteristics, including bistability. The mechanism’s behavior can be tailored by tuning the inherent properties of the helical components, leading to a wide range of responses. This work explores the reconfigurability of the mechanism, based on the ability to change the helical pitch and the resulting stiffness.