Straight-line compliant mechanisms are important building blocks to design a linear-motion stage, which is very useful in precision applications. However, only a few configurations of straight-line compliant mechanism...Straight-line compliant mechanisms are important building blocks to design a linear-motion stage, which is very useful in precision applications. However, only a few configurations of straight-line compliant mechanisms are applicable. To construct more kinds of them, an approach to design large-displacement straight-line flexural mechanisms with rotational flexural joints is proposed, which is based on a viewpoint that the straight-line motion is regarded as a compromise of rigid and compliant parasitic motion of a rotational flexural joint. An analytical design method based on the Taylor series expansion is proposed to quickly obtain an approximate solution. To illustrate and verify the proposed method, two kinds of flexural joints, cross-axis hinge and leaf-type isosceles-trapezoidal flexural（LITF） pivot are used to reconstruct straight-line flexural mechanisms. Their performances are obtained by analytic and FEA method respectively. The comparisons of the results show the accuracy of the approach. Both examples show that the proposed approach can convert a large-deflection flexural joint into approximate straight-line mechanism with a high linearity that is higher than 5 000 within 5 man displacement. This can lead to a new way to design, analyze or optimize straight-line flexure mechanisms.展开更多
Continuum robot has attracted extensive attention since its emergence.It has multi-degree of freedom and high compliance,which give it significant advantages when traveling and operating in narrow spaces.The flexural ...Continuum robot has attracted extensive attention since its emergence.It has multi-degree of freedom and high compliance,which give it significant advantages when traveling and operating in narrow spaces.The flexural virtual-center of motion(VCM)mechanism can be machined integrally,and this way eliminates the assembly between joints.Thus,it is well suited for use as a continuum robot joint.Therefore,a design method for continuum robots based on the VCM mechanism is proposed in this study.First,a novel VCM mechanism is formed using a double leaf-type isosceles-trapezoidal flexural pivot(D-LITFP),which is composed of a series of superimposed LITFPs,to enlarge its stroke.Then,the pseudo-rigid body(PRB)model of the leaf is extended to the VCM mechanism,and the stiffness and stroke of the D-LITFP are modeled.Second,the VCM mechanism is combined to form a flexural joint suitable for the continuum robot.Finally,experiments and simulations are used to validate the accuracy and validity of the PRB model by analyzing the performance(stiffness and stroke)of the VCM mechanism.Furthermore,the motion performance of the designed continuum robot is evaluated.Results show that the maximum stroke of the VCM mechanism is approximately 14.2°,the axial compressive strength is approximately 1915 N/mm,and the repeatable positioning accuracies of the continuum robot is approximately±1.47°(bending angle)and±2.46°(bending direction).展开更多
基金supported by National Natural Science Foundation of China(Grant No.51275552)Foundation for the Author of National Excellent Doctoral Dissertation of China(Grant No.201234)
文摘Straight-line compliant mechanisms are important building blocks to design a linear-motion stage, which is very useful in precision applications. However, only a few configurations of straight-line compliant mechanisms are applicable. To construct more kinds of them, an approach to design large-displacement straight-line flexural mechanisms with rotational flexural joints is proposed, which is based on a viewpoint that the straight-line motion is regarded as a compromise of rigid and compliant parasitic motion of a rotational flexural joint. An analytical design method based on the Taylor series expansion is proposed to quickly obtain an approximate solution. To illustrate and verify the proposed method, two kinds of flexural joints, cross-axis hinge and leaf-type isosceles-trapezoidal flexural（LITF） pivot are used to reconstruct straight-line flexural mechanisms. Their performances are obtained by analytic and FEA method respectively. The comparisons of the results show the accuracy of the approach. Both examples show that the proposed approach can convert a large-deflection flexural joint into approximate straight-line mechanism with a high linearity that is higher than 5 000 within 5 man displacement. This can lead to a new way to design, analyze or optimize straight-line flexure mechanisms.
基金supported in part by the National Natural Science Foundation of China(Grant No.U1813221)the National Key R&D Program of China(Grant No.2019YFB1311200).
文摘Continuum robot has attracted extensive attention since its emergence.It has multi-degree of freedom and high compliance,which give it significant advantages when traveling and operating in narrow spaces.The flexural virtual-center of motion(VCM)mechanism can be machined integrally,and this way eliminates the assembly between joints.Thus,it is well suited for use as a continuum robot joint.Therefore,a design method for continuum robots based on the VCM mechanism is proposed in this study.First,a novel VCM mechanism is formed using a double leaf-type isosceles-trapezoidal flexural pivot(D-LITFP),which is composed of a series of superimposed LITFPs,to enlarge its stroke.Then,the pseudo-rigid body(PRB)model of the leaf is extended to the VCM mechanism,and the stiffness and stroke of the D-LITFP are modeled.Second,the VCM mechanism is combined to form a flexural joint suitable for the continuum robot.Finally,experiments and simulations are used to validate the accuracy and validity of the PRB model by analyzing the performance(stiffness and stroke)of the VCM mechanism.Furthermore,the motion performance of the designed continuum robot is evaluated.Results show that the maximum stroke of the VCM mechanism is approximately 14.2°,the axial compressive strength is approximately 1915 N/mm,and the repeatable positioning accuracies of the continuum robot is approximately±1.47°(bending angle)and±2.46°(bending direction).
