Optimal Design of Hexapod Mechanism Parameters for Large Stroke Flexible Hinge_Hinge Knowledge_Talls1

Abstract:

The performance of a large-stroke flexible hinge Hexapod mechanism is heavily reliant on the performance of the flexible hinge. As the stroke increases, the off-axis stiffness decreases, leading to decreased static stability and accuracy. This paper discusses the solution for the inverse kinematics of the Hexapod mechanism, including the expansion and contraction length of each branch and the rotation angle of each hinge. Additionally, it explores the optimization of parameters for the large-stroke flexible hinge Hexapod mechanism. The goal is to minimize the stroke requirements for each hinge while still meeting the motion space requirements of the moving platform.

Optical systems are widely used in precision engineering fields such as microscopy, semiconductor production, and space exploration. Precise positioning of optical components is crucial for maintaining optical accuracy. The Hexapod mechanism offers precise positioning for traditional optical components using flexible hinges as kinematic pairs. These hinges have a simple structure, no friction, and high precision. However, traditional fully flexible parallel robots have limited working spaces, usually in the cubic micron range. To achieve larger strokes, a two-stage kinematic mechanism can be used. This approach increases system complexity and cost. This paper focuses on optimizing the parameter design of a large-stroke flexible hinge Hexapod mechanism, with a specific application to the precise positioning of optical components.

1. Kinematics Inverse Solution:

The paper establishes a pseudo-rigid body model of the flexible hinge Hexapod mechanism. The flexible hinge between the strut and moving platform is assumed to be a spherical joint with rotational stiffness, while the flexible hinge between the strut and fixed platform is assumed to be a universal hinge. The kinematics inverse solution involves determining the rotation angle of the flexible hinge. This is done by calculating the rotation matrix of each joint and solving for the joint rotation angles. The result is a set of inverse solutions for the five joints of each branch chain.

2. Hexapod Parameter Optimization:

The paper proposes a parameter optimization design for the Hexapod mechanism. The objective is to minimize the maximum deformation of all flexible hinges while meeting the workspace requirements. Design parameters include the radius of the circles where the flexible hinges are connected, the angle between lines connecting certain points, and the height between the fixed and moving platforms. The optimization is done by finding the minimum weighted sum of the maximum angle and movement of the flexible hinges under different parameter combinations. The results show that the design parameters can be classified into three categories: rotation-oriented, linear-guided, and comprehensive optimization.

In conclusion, this paper presents an optimal design for the parameter optimization of a large-stroke flexible hinge Hexapod mechanism. The inverse kinematics solution is analyzed, and the parameters of the Hexapod mechanism are optimized to minimize the deformation of the flexible hinge while meeting the workspace requirements. The results demonstrate the importance of considering both rotation and expansion in the design, and highlight the need for comprehensive optimization. The findings provide valuable insights for the design and optimization of Hexapod mechanisms in applications requiring large-stroke movements.