Nonlinear flexure coupling elements for precision control of multibody systems

Abstract

<jats:p>Conventional multibody systems used in robotics and automated machinery contain bearing components that exhibit complex and uncertain tribological characteristics. These limit fundamentally the precision of the automated motion and also cause wear. Replacing traditional bearing joints with flexure couplings eliminates these tribological effects, together with wear, reducing necessary system maintenance and offering a potential for increased motion precision. A flexure-coupled multibody system is considered and a novel general solution technique is presented. Derivation of a large deflection flexure coupling model is provided and subsequently validated using an experimental facility. A focused study of a unique double-flexure-coupling rigid body system is given; the formulated nonlinear mathematical model can be used for feedforward control. Equivalent control is also applied to a corresponding system with traditional bearing joints. The feasibility of replacing bearing joints by flexure couplings is demonstrated in terms of accurate large displacement control and reduction of high-frequency disturbances.</jats:p>

Iterative Feedforward Control for Bearing-Free Multibody Systems

“…A PF which consists of monolithic material with suitable elastic properties for large elastic deformation is investigated. A mathematical model for the PF is derived using nonlinear Euler-Bernoulli large deformation beam theory (Bailey et al, 2018). The PF model details are introduced in this section to demonstrate the difficulty associated with modelling more complex (e.g., cross-) flexure coupling designs.…”

“…Accurate and fast analysis of multiple planar compliant mechanisms with distributed or concentrated compliance is achieved. A plain large deformation flexure coupling consisting of a single section of spring steel has been investigated by Bailey et al (2018) for precision control in a two-flexure coupling-rigid body system. The control methodology was derived from a bespoke large deformation nonlinear mathematical model and results showed the advantages of flexure couplings included elimination of high frequency behaviour associated with the excitation of the nonlinear effects in conventional bearing components.…”