Structural synthesis for 4-DOF parallel manipulators using screw theory issystematically studied. Motion properties and constraint conditions of 4-DOF parallel manipulatorsaccording to the relationship between screw a...Structural synthesis for 4-DOF parallel manipulators using screw theory issystematically studied. Motion properties and constraint conditions of 4-DOF parallel manipulatorsaccording to the relationship between screw and reciprocal screw are analyzed. Mathematicalexpressions for constraint screws and twist screws of moving platform are constructed, and allpossible limbs, which provide one or more force constraints, are enumerated. Finally, a parallelmanipulator with 3-rotation-DOF and 1-translation-DOF is used as an example to describe thesynthesis procedure for symmetrical and non-symmetrical 4-DOF parallel manipulators.展开更多
This paper presents a mechanism theory principle for equivalent substitution in kinematic chain of a higher pair for lower pairs. This is the opposite of the principle of the equivalent substitution of lower pairs for...This paper presents a mechanism theory principle for equivalent substitution in kinematic chain of a higher pair for lower pairs. This is the opposite of the principle of the equivalent substitution of lower pairs for a higher pair. Also presented here is a new approach for isomorphism identification in kinematic chains containing higher pairs(KCCHs). Based on this approach, an algorithm for generating nonisomorphic KCCHs has been developed. This algorithm is not restricted by the number of links, the degree of freedom or the number of higher pairs. Using this algorithm, nonisomorphic KCCHs can be generated automatically from the kinematic chains that contain only lower pairs. As an application of this algorithm, all the nonisomorphic KCCHs with N<10(N, the number of links), F≤3 (F, the degree of KCCHs), and H≤2(H, the number of higher pairs) are computer generated. 展开更多
文摘Structural synthesis for 4-DOF parallel manipulators using screw theory issystematically studied. Motion properties and constraint conditions of 4-DOF parallel manipulatorsaccording to the relationship between screw and reciprocal screw are analyzed. Mathematicalexpressions for constraint screws and twist screws of moving platform are constructed, and allpossible limbs, which provide one or more force constraints, are enumerated. Finally, a parallelmanipulator with 3-rotation-DOF and 1-translation-DOF is used as an example to describe thesynthesis procedure for symmetrical and non-symmetrical 4-DOF parallel manipulators.
文摘This paper presents a mechanism theory principle for equivalent substitution in kinematic chain of a higher pair for lower pairs. This is the opposite of the principle of the equivalent substitution of lower pairs for a higher pair. Also presented here is a new approach for isomorphism identification in kinematic chains containing higher pairs(KCCHs). Based on this approach, an algorithm for generating nonisomorphic KCCHs has been developed. This algorithm is not restricted by the number of links, the degree of freedom or the number of higher pairs. Using this algorithm, nonisomorphic KCCHs can be generated automatically from the kinematic chains that contain only lower pairs. As an application of this algorithm, all the nonisomorphic KCCHs with N<10(N, the number of links), F≤3 (F, the degree of KCCHs), and H≤2(H, the number of higher pairs) are computer generated.
