Kinematic design
Linkages are among the most classical and typical constructs in general mechanical engineering. In precision engineering, oftentimes flexures are applied, which are covered in Chapter 3. Nonetheless, in many important cases, linkage type transmissions are useful, while also the kinematic concepts that were developed for linkages bear direct relevance for flexure mechanisms. Therefore, this chapter will treat some basics of kinematics and linkage synthesis.
This chapter will treat basic kinematic concepts like degrees of freedom, mobility, static determinacy, kinematic determinacy, exact constraintness, instantaneous center of rotation, singularity, mechanical and geometrical advantage, transmission angles and their relationships. Normally, singularities are to be avoided but situations will be discussed where profitable use is made of them. Similarly, while exactly constrained designs have important advantages, there can be good reasons to consciously deviate from this paradigm. Methods for kinematic analysis and synthesis will be explained, from classical ones such as Grübler-Kutzbach-Chebychev to modern ones like Freedom and Constraint Topology.
Special attention is directed to elements to constrain degrees of freedom, ranging from joints or kinematic pairs, typically used to allow certain motions, to kinematic couplings that are typically used for repeatable positioning. In the latter case, unilateral constraints are used which leads to the need for an extra constraint or so-called nesting force. Methods for the determination of suitable configurations will be provided.
Cases:
- Statically determined long stroke linear guide
- Additive manufactured laser alignment mechanism
- Allowable misalignment in an overconstrained flexure mechanism
- Allowable misalignments in an overconstrained flexure mechanism: The cross-hinge
- Effects of misalignments on the static and dynamic behavior of a multiple overconstrained compliant 4-bar mechanism
- Exact Constraint Design of a Two-Degree of Freedom Flexure-Based Mechanism
- 5 DOF bike hub force sensor
- Spherical kinematic mount for a Fizeau interferometer
- Large stroke high off-axis stiffness 3DOF spherical flexure joint
- Fully flexure-based large range of motion precision hexapod
- Large range of motion flexure hinge: Infinity flexure
- Flexure based 6 DOF parallel manipulator for fast adaptive optics
- Flexure mechanism for eye surgery pump
- Flexures in a heavy duty H-drive gantry
- Optimal release locations in assembled overconstrained mechanisms for static determinacy
- Bed of Nails increase vibration mode frequencies
- Collimator for CT scanner with 35g centrifugal load
- Improved dynamics by overconstraining using viscoelastic material
- Ultra-stable iso-static bonded optical mount design
- Tip-tilt mirror mechanism with large dynamic range
- Donator, a precision large reduction single-stage transmission mechanism.
- Increasing load capacity and support stiffness of flexures by overconstraining
- T-Flex-LC: A flexure-based hexapod with a simplified kinematic structure
- Double Watts flexure mechanism for a precision vacuum adhesion and friction tester
- Flexure assembly by brazing
- Flexure assembly using Dove tail clamps
- Superconducting magnet plate for planar motor application