Type Synthesis of Self-Alignment Parallel Ankle Rehabilitation Robot with Suitable Passive Degrees of Freedom

The current parallel ankle rehabilitation robot(ARR)suffers from the problem of difficult real-time alignment of the human-robot joint center of rotation,which may lead to secondary injuries to the patient.This study investigates type synthesis of a parallel self-alignment ankle rehabilitation robot(PSAARR)based on the kinematic characteristics of ankle joint rotation center drift from the perspective of introducing"suitable passive degrees of freedom(DOF)"with a suitable number and form.First,the self-alignment principle of parallel ARR was proposed by deriving conditions for transforming a human-robot closed chain(HRCC)formed by an ARR and human body into a kinematic suitable constrained system and introducing conditions of"decoupled"and"less limb".Second,the relationship between the self-alignment principle and actuation wrenches(twists)of PSAARR was analyzed with the velocity Jacobian matrix as a"bridge".Subsequently,the type synthesis conditions of PSAARR were proposed.Third,a PSAARR synthesis method was proposed based on the screw theory and type of PSAARR synthesis conducted.Finally,an HRCC kinematic model was established to verify the self-alignment capability of the PSAARR.In this study,93 types of PSAARR limb structures were synthesized and the self-alignment capability of a human-robot joint axis was verified through kinematic analysis,which provides a theoretical basis for the design of such an ARR.

RhMYB108,an R2R3-MYB transcription factor,is involved in ethylene-and JA-induced petal senescence in rose plants

Rose(Rosa hybrida)plants are major ornamental species worldwide,and their commercial value greatly depends on their open flowers,as both the quality of fully open petals and long vase life are important.Petal senescence can be started and accelerated by various hormone signals,and ethylene is considered an accelerator of petal senescence in rose.To date,however,the underlying mechanism of signaling crosstalk between ethylene and other hormones such as JA in petal senescence remains largely unknown.Here,we isolated RhMYB108,an R2R3-MYB transcription factor,which is highly expressed in senescing petals as well as in petals treated with exogenous ethylene and JA.Applications of exogenous ethylene and JA markedly accelerated petal senescence,while the process was delayed in response to applications of 1-MCP,an ethylene action inhibitor.In addition,silencing of RhMYB108 alter the expression of SAGs such as RhNAC029,RhNAC053,RhNAC092,RhSAG12,and RhSAG113,and finally block ethylene-and JA-induced petal senescence.Furthermore,RhMYB108 was identified to target the promoters of RhNAC053,RhNAC092,and RhSAG113.Our results reveal a model in which RhMYB108 functions as a receptor of ethylene and JA signals to modulate the onset of petal senescence by targeting and enhancing senescence-associated gene expression.

Author Correction: RhMYB108, an R2R3-MYB transcription factor, is involved in ethylene- and JA-induced petal senescence in rose plants

After publication of our article[1],we became aware that there were errors in Fig.7b,namely the negative control of pLacZi+pJG4-5-RhMYB108(2nd row,panel 1).The error does not affect the result,discussion or conclusion in the article.The correct version of Figure is shown below.We apologise to the journal and to readers for this error.

Topological Configuration and Rotation Analysis of the Three⁃Order Rubik􀆳s Cube

The mechanism of three⁃order Rubik􀆳s Cube(RC)has the characteristics of recombination and variable degree of freedom,and it is difficult to accurately describe the degree of its freedom.This paper takes RC as the research object,and the adjacency matrix is constructed based on topology and graph theory in order to describe the variation rule of topological configuration in the single layer rotation of RC.In this paper,the degree of freedom of the RC in any shape can be described by defining the concept of entanglement degree of freedom,establishing a set of adjacency matrix,and determining the degree of freedom of the RC which is attributed to the number of non⁃zero elements in the set of adjacent matrix.The prime number is proposed to describe the rotation of the RC combined with the rotation recognition of RC,which is simple and convenient for computer processing.The research contents in this paper are beneficial to the study of RC from the perspective of mechanism science.Meanwhile,it is of great significance to the study of other complex mechanisms with variable degrees of freedom.

A general methodology for mobility analysis of mechanisms based on constraint screw theory

It is well known that the traditional Grübler-Kutzbach formula fails to calculate the mobility of some classical mechanisms or many modern parallel robots,and this situation seriously hampers mechani-cal innovation.To seek an efficient and universal method for mobility calculation has been a heated topic in the sphere of mechanism.The modified Grübler-Kutzbach criterion proposed by us achieved success in calculating the mobility of a lot of highly complicated mechanisms,especially the mobility of all recent parallel mechanisms listed by Gogu,and the Bennett mechanism known for its particular difficulty.With wide applications of the criterion,a systematic methodology has recently formed.This paper systematically presents the methodology based on the screw theory for the first time and ana-lyzes six representative puzzling mechanisms.In addition,the methodology is convenient for judgment of the instantaneous or full-cycle mobility,and has become an effective and general method of great scientific value and practical significance.In the first half,this paper introduces the basic screw theory,then it presents the effective methodology formed within this decade.The second half of this paper presents how to apply the methodology by analyzing the mobility of several puzzling mechanisms.Finally,this paper contrasts and analyzes some different methods and interprets the essential reason for validity of our methodology.