We demonstrate mass-producible, tetherless microgrippers that can be remotely triggered by temperature and chemicals under biologically relevant conditions. The microgrippers use a self-contained actuation response, obviating the need for external tethers in operation. The grippers can be actuated en masse, even while spatially separated. We used the microgrippers to perform diverse functions, such as picking up a bead on a substrate and the removal of cells from tissue embedded at the end of a capillary (an in vitro biopsy).

Tetherless thermobiochemically actuated microgrippers.

Besides continuing effort in developing MEMS-based manufacturing techniques, latest effort in micro-manufacturing is also in non-MEMS-based manufacturing. Research and technological development in this field is encouraged by the increased demand on micro-components as well as promised development in the scaling down of the traditional macro-manufacturing processes for micro-length-scale manufacturing. This paper highlights some EU funded research activities in micro/nano-manufacturing, and gives examples of the latest development in micro-manufacturing methods/techniques, process chains, hybrid processes, manufacturing equipment and supporting technologies/device, etc., which is followed by a summary of the achievements of the EU MASMICRO project. Finally, concluding remarks are given, which raise several issues concerning further development in micro-manufacturing.

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Micro-manufacturing: research, technology outcomes and development issues

High-speed simultaneous position and contact force control is vital for microgrippers dedicated to automated high-throughput microassembly tasks. This paper presents the design and validation of a new robust impedance control for high-speed position and force regulation of a compliant gripper which is driven by a piezoelectric stack actuator. Unlike traditional position/force switching control, the proposed scheme enables a smooth transition between the free and constrained motions of the gripper. A single controller is devised to regulate both the gripper tip position and the contact force, rendering a simplification in control design. The stability of the closed-loop system in the presence of piezoelectric nonlinearities is guaranteed by a digital sliding mode impedance control algorithm. Moreover, the proposed control scheme is applicable to high-order systems, and the control algorithm simplification enables a high-speed loop rate. The high-speed control is realized by deploying the algorithm to a field-programmable gate array controller. The effectiveness of the proposed scheme is verified through experimental studies on grasp–hold–release operation of a graphite microrod. The control scheme can be extended to other microassembly systems as well.

Robust Impedance Control of a Compliant Microgripper for High-Speed Position/Force Regulation

Industry 4.0 aims at integrating machines and operators through network connections and information management. It proposes the use of a set of technologies in industry, such as data analysis, Internet of Things, cloud computing, cooperative robots, and immersive technologies. This paper presents a training system for industrial operators in assembly tasks, which takes advantage of tools such as virtual reality and process mining. First, expert workers use an immersive interface to perform assemblies according to their experience. Then, process mining algorithms are applied to obtain assembly models from event logs. Finally, trainee workers use an improved immersive interface with hints to learn the assemblies that the expert workers introduced in the system. A toy example has been developed with building blocks and tests have been performed with a set of volunteers. The results show that the proposed training system, based on process mining and virtual reality, is competitive against conventional alternatives. Furthermore, user evaluations are better in terms of mental demand, perception, learning, results, and performance.

A training system for Industry 4.0 operators in complex assemblies based on virtual reality and process mining

Reconfigurable Manufacturing System (RMS) is one of most promising paradigms that provide an effective solution to changes and uncertainties in a competitive manufacturing environment. A Reconfigurable Assembly System (RAS) is a key component of an RMS. In this paper, our survey on the development of RAS has been summarised. The objectives of this literature survey are to: • clarify the needs and drivers in developing reconfigurable assembly systems • identify both academic and practical issues critical to the development of reconfigurable assembly systems • understand the state of the art of R&D related to the studies on the critical issues

Current status of reconfigurable assembly systems

This paper provides a comprehensive review of research efforts in the emerging field of micro devices assembly (MDA) as well as identifies future directions for research. The general domain dealing with both manual and automated assembly of micro devices can be referred to as MDA. The study of computer-based methods to accomplish the assembly of micron-sized parts can be described as Automated MDA (AMDA). The primary focus of this paper is to provide an overview of concepts related to MDA as well as a review of various segments of MDA research including study of the role of interactive forces at the micro level, the design of innovative gripping and assembly techniques as well as the use of information technology (IT) based approaches.

Assembly and manipulation of micro devices-A state of the art survey

This paper provides a review of micro-assembly-related research activities and their findings. The assembly of micro-devices involves handling of parts that are extremely small (in the order of 10−6 m). Part designs, which are complex in shape and require the use of material of varying properties, cannot be manufactured using Micro-Electro Mechanical Systems (MEMS) technology; in such situations, assembly of micron-sized parts is necessary. Gripping techniques using micro-grippers and other manipulation/assembly tools are needed to accomplish micro-assembly tasks. The literature reviewed in this paper includes micro-gripping techniques and manipulation strategies, integrated micro-assembly systems design and implementation as well as computer-based approaches to aid in micro-assembly applications.

A review of gripping and manipulation techniques for micro-assembly applications

In this paper, the design and development of a physical and virtual environment to support assembly of micron sized devices is discussed. Micro assembly involves handling and assembling of micron sized parts (10−6 m). As manual assembly of micron-sized parts is difficult and tedious, the design of computer assisted micro-assembly techniques becomes crucial. An Integrated Physical and Virtual Reality (VR) environment has been created to aid in the assembly of such micro devices, which supports the establishment of an interface between a virtual and physical micro assembly work cell. The overall architecture and the various modules implemented in this environment are outlined in this paper.

Derek Powell

Papers

Assembly and manipulation of micro devices-A state of the art survey

A review of gripping and manipulation techniques for micro-assembly applications

Micro devices assembly using virtual environments