《机械原理》课程PPT教学课件（Theory of Machines and Mechanisms）Chap2 Kinematics fundamental

Chap.2 Kinematics fundamental 2.1 Basic Concept 2.2 Determining Degree of Freedom 2.3 How does a kinematic chains transform into a mechanism? 2.4 Kinematic Diagram of Mechanism 2.5 Principle of Mechanism Constitution

Chap.2 Kinematics fundamental 2.1 Basic Concept 2.2 Determining Degree of Freedom 2.3 How does a kinematic chains transform into a mechanism? 2.4 Kinematic Diagram of Mechanism 2.5 Principle of Mechanism Constitution

2.1 Basic Concepts of Mechanisms Degree of freedom(自由度) Link(构件) Kinematic Pairs(Joints)(运动副) Machine Element(机械零件) Fixed link(frame)(机架) Crank,couple,rocker(曲柄、连杆、摇杆) Kinematic Chain(运动链) Mechanism(机构) Machine(机器)

2.1 Basic Concepts of Mechanisms Degree of freedom (自由度) Link （构件） Kinematic Pairs (Joints)（运动副） Machine Element（机械零件） Fixed link ( frame)（机架） Crank, couple,rocker（曲柄、连杆、摇杆） Kinematic Chain（运动链） Mechanism（机构） Machine（机器）

Degree of Freedom(自由度) The system's DOFis equal to the number of independent parameters which are needed to uniquely define its position in space at any instant of time

Degree of Freedom（自由度） The system’s DOF is equal to the number of independent parameters which are needed to uniquely define its position in space at any instant of time

Link(构件)：is a rigid body which possesses at lease two nodes which are points for attachment to other links. Ternary link nodes nodes Binary link Quaternary link

Link（构件）:is a rigid body which possesses at lease two nodes which are points for attachment to other links. nodes Ternary link Binary link Quaternary link nodes

Joint(铰链或运动副) Joint:is a connection between two or more links(at their nodes),which allows some motion,or potential motion,between the connected links. Joints (also called kinematic pairs)can be classified in several ways: 1. By the type of contact between the elements,line, point,or surface. 2. By the number of degree of freedom allowed at the joint. 3. Others

Joint: is a connection between two or more links(at their nodes), which allows some motion, or potential motion, between the connected links. Joints (also called kinematic pairs) can be classified in several ways: 1. By the type of contact between the elements, line, point, or surface. 2. By the number of degree of freedom allowed at the joint. 3. Others Joint (铰链或运动副)

Lower pairs(低副)：joints with surface contact Prismatic joint Revolute joint Cylindric joint Spherical joint Helical joint Planar joint Type Pjoint R joint Cjoint S joint Hjoint F joint DOF 2 3

Lower pairs（低副）:joints with surface contact Prismatic joint Revolute joint Cylindric joint Spherical joint Helical joint Planar joint Type P joint R joint C joint S joint H joint F joint DOF 1 1 2 3 1 3

Higher pairs(高副)：joints with point or line contact DOF

Higher pairs（高副）:joints with point or line contact DOF 5 2

Examples of higher pairs Form-closed Force-closed closed by its geometry need external force

Examples of higher pairs Force –closed need external force Form –closed closed by its geometry

Diagram of Kinematic pairs(运动副简图) Prismatic joint Revolute joint Cylindric joint Spherical joint Helical joint Diagram Type Pjoint R joint C joint S joint Hjoint DOF 1 2 3 1

Diagram of Kinematic pairs（运动副简图） Prismatic joint Revolute joint Cylindric joint Spherical joint Helical joint Type P joint R joint C joint S joint H joint DOF 1 1 2 3 1 Diagram

Machine Element(机械零件)：minimum unit during manufacturing This link has several machine elements Binary link

Machine Element（机械零件）: minimum unit during manufacturing Binary link This link has several machine elements