Design and analysis of a compliant parallel pan-tilt platform

In combination of the advantages of both parallel mechanisms and compliant mechanisms, a compliant parallel mechanism with two rotational DOFs (degrees of freedom) is designed to meet the requirement of a lightweight and compact pan-tilt platform. Firstly, two commonly-used design methods i.e. direct substitution and FACT (Freedom and Constraint Topology) are applied to design the configuration of the pan-tilt system, and similarities and differences of the two design alternatives are compared. Then inverse kinematic analysis of the candidate mechanism is implemented by using the pseudo-rigid-body model (PRBM), and the Jacobian related to its differential kinematics is further derived to help designer realize dynamic analysis of the 8R compliant mechanism. In addition, the mechanism’s maximum stress existing within its workspace is tested by finite element analysis. Finally, a method to determine joint damping of the flexure hinge is presented, which aims at exploring the effect of joint damping on actuator selection and real-time control. To the authors’ knowledge, almost no existing literature concerns with this issue.

A multi-technology approach to identifying the reasons for lateral drift in professional and recreational darts

This work performs an extensive charterisation of precision targeted throwing in professional and recreational darts. The goal is to identify the contributing factors for lateral drift or throwing inaccuracy in the horizontal plane. A multitechnology approach is adopted whereby a custom built body area network of wireless inertial measurement devices monitor tilt, force and timing, an optical 3D motion capture system provides a complete kinematic model of the subject, electromyography sensors monitor muscle activation patterns and a force plate and pressure mat capture tactile pressure and force measurements. The study introduces the concept of constant throwing rhythm and highlights how landing errors in the horizontal plane can be attributable to a number of variations in arm force and speed, centre of gravity and the movements of some of the bodies non throw related extremities.

Broadband cavity-enhanced absorption spectroscopy with incoherent light

Although broadband incoherent light does not efficiently couple into a high-finesse optical cavity, its transmission is readily detectable and enables applications in cavity-enhanced absorption spectroscopy in the gas phase, liquid phase and on surfaces. This chapter gives an overview of measurement principles and experimental approaches implementing incoherent light sources in cavity-enhanced spectroscopic applications. The general principles of broadband CEAS are outlined and general “pros and cons” discussed, detailing aspects like cavity mirror reflectivity calibration or the establishment of detection limits. Different approaches concerning light sources, cavity design and detection schemes are discussed and a comprehensive overview of the current literature based on a methodological classification scheme is also presented.