Design of compliant mechanisms using continuum topology optimization: A review

Lattice structures, which are also known as architected cellular structures, have been applied in various industrial sectors, owing to their fascinated performances, such as low elastic modulus, high stiffness-to-weight ratio, low thermal expansion coefficient, and large specific surface area. The lattice structures fabricated by conventional manufacturing technologies always involve complicated process control, additional assembly steps, or other uncontrollable factors. Furthermore, limited types of unit cells can be used to construct lattice structures when using conventional processes. Fortunately, additive manufacturing technology, based on a layer-by-layer process from computer-aided design models, demonstrates the unique capability and flexibility and provides an ideal platform in manufacturing complex components like lattice structures, resulting in an effective reduction in the processing time to actual application and minimum of material waste. Therefore, additive manufacturing relieves the constraint of structure design and provides accurate fabrication for lattice structures with good quality. This work systematically presents an overview of conventional manufacturing methods and novel additive manufacturing technologies for metallic lattice structures. Afterward, the design, optimization, a variety of properties, and applications of metallic lattice structures produced by additive manufacturing are elaborated. By summarizing state-of-the-art progress of the additively manufactured metallic lattice structures, limitations and future perspectives are also discussed.

Additive manufacturing of metallic lattice structures: Unconstrained design, accurate fabrication, fascinated performances, and challenges

Vibration control based metamaterials and origami structures: A state-of-the-art review

Improving the functionality of soft continuum manipulators to expand their application space has always been an important development direction for soft robotics. It remains very challenging to calculate the deformations of soft materials and predict the basic structure of soft fingers under complex objective functions and constraints. This work develops a cable-driven soft robotic gripper with multi-input and multi-output using topology optimization considering geometric nonlinearity, which not only performs adaptive grasping but also enables finer manipulations such as rotating or panning the target. A scheme that can describe adaptive grasping behavior is proposed, which converts the contact between the clamping surface and the object into a boundary condition to circumvent complex contact nonlinearities. An additive hyperelasticity technique is used to overcome numerical instabilities, and the finite element analysis is performed in ANSYS. Numerical simulations and experimental results are performed to demonstrate the effectiveness of the optimization algorithm and to illustrate the application potential of the proposed gripper.

Topology optimization of a cable-driven soft robotic gripper

The piezoelectric-actuated compliant microgripper (PEACM) plays an essential role in the application fields such as biomedical engineering, microelectronics, and optical engineering. As compared with other categories of grippers, PEACM exhibits the advantages of high accuracy of displacement, large power to weight ratio, low energy consumption, and fast response speed. This paper reviews the recent advances on performance indices, classification, structural composition, optimization and modeling method, and control of PEACM. First, the gripper's performance indices and classifications are elaborated, which is beneficial to determine the design goal. Then, the compliant mechanisms adopted in the microgripper design are discussed, including the flexible hinge, displacement amplifier, and guiding mechanism. In addition, the optimization and modeling methods of the microgripper are presented. Popular types of position/force sensors and different displacement/force control strategies employed in the microgripper are surveyed. Moreover, the prospect on future development trend of the PEACM is discussed. The paper provides the reader with an overview of the recent advances on PEACM design and also a guideline on further development of the microgripper.

Recent design and development of piezoelectric-actuated compliant microgrippers: A review

Topology optimization of bistable mechanisms with maximized differences between switching forces in forward and backward direction

Compliant kaleidocycles can be widely used in a variety of applications, including deployable structures, origami structures, and metamorphic robots, due to their unique features of continuous rotatability and multistability. Inspired by origami kaleidocycles, a type of symmetric multistable compliant mechanism with an arbitrary number of units is presented and analyzed in this paper. First, the basic dimension constraints are developed based on mobility analysis using screw theory. Second, the kinematic relationships of the actual rotation angle are obtained. Third, a method to determine the number of stabilities and the position of stable states, including the solution for the parameterized boundaries of stable regions, is developed. Finally, experimental platforms are established, and the validity of the proposed multistable mechanisms is verified.

Hongchuan Zhang

Papers

Design of compliant mechanisms using continuum topology optimization: A review

Topology optimization of a cable-driven soft robotic gripper

Topology optimization of bistable mechanisms with maximized differences between switching forces in forward and backward direction

Origami Kaleidocycle-Inspired Symmetric Multistable Compliant Mechanisms

A novel flexural lamina emergent spatial joint