Design, Fabrication and Implementation of Kinematic Coupling Technology
Martin L. Culpepper, Massachusetts Institute of Technology

Precision engineers face a constant battle to provide practical fixturing technologies for experiments and manufacturing processes. It is important for them to be able to identify appropriate fixturing technologies and then design, fabricate and implement these technologies. This tutorial will cover the concepts and theory which govern how kinematic couplings/fixtures are designed, manufactured and best-used in practice. Emphasis is placed on deterministic modeling of performance (accuracy, precision and stiffness) and hands-on experiments. The tutorial consists of four sections:

(1) Passive alignment [1 hour]:
Covers the concepts and theory which govern the design and optimization of kinematic couplings. We will examine:
(a) How to design coupling constraints: selecting the appropriate number, location, orientation, and geometric/material properties of constraints
(b) Factors that limit coupling repeatability and accuracy: surface finish, thermal errors, variable loading, friction and wear

(2) Active alignment [1 hour]:
Many emerging applications require nanometer-level accuracy and precision. This can be achieved by incorporating mechanisms, actuators and sensors which work together within a fixture to actively correct misalignment errors. We will cover the fundamental concepts and the theory which govern the kinematic motions of active fixtures, fixture performance and the choice of actuators and sensors.

(3) Design simulators [0.5 hours]:
Participants will learn how to use simulation tools (Excel spread sheets) to design/optimize passive and active kinematic couplings. Tablet PCs will be provided for the purpose of this exercise. The simulation results obtained in section 3 will be compared with experimental results obtained in the following section.

(4) Hands-on experiments [1.5 hours]
Experiments will be run to demonstrate the proper use of these technologies and to enable attendees to gain hands-on experience with the technologies. Exercises will explore concepts such as stiffness, repeatability, effect of lubrication, effect of preload, order of engagement.