Towards the design of monolithic decoupled XYZ compliant parallel mechanisms for multi-function applications

Abstract

Abstract. This paper deals with the monolithic decoupled XYZ compliant parallel mechanisms (CPMs) for multi-function applications, which can be fabricated monolithically without assembly and has the capability of kinetostatic decoupling. At first, the conceptual design of monolithic decoupled XYZ CPMs is presented using identical spatial compliant multi-beam modules based on a decoupled 3-PPPR parallel kinematic mechanism. Three types of applications: motion/positioning stages, force/acceleration sensors and energy harvesting devices are described in principle. The kinetostatic and dynamic modelling is then conducted to capture the displacements of any stage under loads acting at any stage and the natural frequency with the comparisons with FEA results. Finally, performance characteristics analysis for motion stage applications is detailed investigated to show how the change of the geometrical parameters can affect the performance characteristics, which provides initial optimal estimations. Results show that the smaller thickness of beams and larger dimension of cubic stages can improve the performance characteristics excluding natural frequency under allowable conditions. In order to improve the natural frequency characteristic, a monolithic decoupled configuration that is achieved through employing more beams in the spatial modules or reducing the mass of each cubic stage mass can be adopted. In addition, an isotropic variation with different motion range along each axis and same payload in each leg is proposed. The redundant design for monolithic fabrication is introduced in this paper, which can overcome the drawback of monolithic fabrication that the failed compliant beam is difficult to replace, and extend the CPM's life.

Conceptual designs of multi-degree of freedom compliant parallel manipulators composed of wire-beam based compliant mechanisms

“…5) is adopted in terms of the proposed decoupled XYZ CPM (Fig. 4), which can be fabricated monolithically from a cubic material by three orthogonal directions' cutting [33]. The improved design is composed of eight rigid cubic stages organically connected by twelve identical WBBCM3-1s to form a monolithic and compact cubic configuration (extra three WBBCM3-1s are added compared with Fig.…”

“…When any four adjacent rigid stages are fixed in the non-deformed configuration (and therefore three WBBCM3-1s are inactive), the other four rigid stages act as the mobiles stages (X-, Y-, Z-, and XYZ-stages), displaced by the deformation of the nine WBBCM3-1s, to achieve the function of XYZ CPMs. The detailed linear analytical modelling and optimization results can be found in [33].…”

“…However, the present monolithic decoupled XYZ CPM in this paper is a redundant design with extended life [33] through three redundant building blocks (inactive WBBCM3-1s), and therefore the three redundant building blocks can swap the functions with the three passive mobile building blocks to extend the system life. In our design (Fig.…”

“…For example, a number of synthesis works for WBBCMs have been reported in [25][26][27][28][29][30][31], spatial 3-DOF translational compliant parallel manipulators only composed of identical WBBCMs have been proposed in [32,33], and nonlinear analysis/modelling has been carried out for WBBCMs in [34,35]. In comparison with the leaf-beam based distributed-compliance compliant mechanisms, the WBBCMs benefit from the following potential merits:…”

Design and analysis of a 3-DOF planar micromanipulation stage with large rotational displacement for micromanipulation system

“…Generally speaking, the flexure-based micromanipulation stage has limited workspace, to overcome this drawback, many different kinds of amplification mechanisms are adopted to amplify the stroke of piezoelectric actuators. Lu et al designed compliant parallel micro motion stage with two translations (along X and Y direction) and one rotation (around Z axis), also adopted piezoelectric actuators, but without amplification mechanism, the drawback of this design is the very small workspace (Lu et al, 2004); Bhagat et al also designed a planar 3-DOF micromanipulator, this mechanism adopted three piezoelectric actuators to achieve required displacements in X, Y and θ and utilized lever amplifier to enhance the displacement of the mechanism (Bhagat et al, 2014); Hao fabricated a flexure-based spatial 3-DOF compliant parallel mechanism with three translational motions along X, Y and Z axis, respectively, moreover this monolithic CPM can be used as positioning stage, acceleration sensor and energy harvesting device (Hao, 2013); Wang and Zhang proposed a 3-DOF nanopositioning stage with two-level lever amplifier with over two hundreds of microns translational displacement along x/y, however the rotational scope and natural frequency are relatively small in Wang and Zhang (2016). In addition, other researchers have also designed many kinds of 3-DOF compliant parallel stages with different characteristics (Dong et al, 2016;Tian and Shirinzadeh, 2009).…”