ABSTRACT
206Kinematics is the study of motion, without regard for the cause of the motion, of a rigid body in space and its relation to other bodies. In designing precision mechanics, kinematic considerations are always important when parts of a mechanism move relative to each other both in operating conditions and during assembly of the mechanism. The accuracy and stability of precision mechanics can be improved significantly by following fundamental kinematic principles. Since the role of kinematics is to ensure the functionality of the mechanism, to be effective, a kinematic approach to design will include: (1) adherence to kinematic principles, (2) evaluation of kinematic design options based on practical considerations and (3) design, such as position, velocity and acceleration analysis, of the mechanism or machine. Hence, this chapter is organised focusing on the first two criteria, while the third is introduced in Chapter 8 (system modelling). In this chapter, the basic kinematic principles are explained, followed by a discussion of some practical considerations that demonstrate the motivation for the development of pseudo-kinematic design as opposed to pure kinematic design. Readers will also be familiarised with fundamental kinematic structures most commonly used in precision machines and mechanisms. Illustrated examples are used to demonstrate how kinematic principles are realised in design.
