Multiple Microrobots Research Articles

Unknown Environment Mapping Based on Multiple Micro-Robots

Currently, most mapping researches are deeply dependent on long range sensors such as sonar, laser range finders or cameras, but due to power or cost constraints, which often cannot be mounted in the sensor module. In response to the no long range sensors situation, this paper presents a method to complete indoor mapping tasks in real-time only using short range sensors installed on the multiple micro-robots. The key mapping problem needed to address in the paper is that each single robot created a map based on odometer and short distance sensor data, and then maps from multiple robots were consolidated to generate a greater coherence map. A kind of SRV mobile robots were tested in an artificial rectangular environment. The experimental results show that the multiple micro-robot system has good robustness to odometer and environmental noise.

Towards Mobile Microrobot Swarms for Additive Micromanufacturing

In this paper, a novel approach to achieving the independent control of multiple magnetic microrobots is presented. The approach utilizes a specialized substrate consisting of a fine grid of planar, MEMS-fabricated micro coils of the same size as the microrobots (≤ 500 μm). The coils can be used to generate real magnetic potentials and, therefore, attractive and repulsive forces in the workspace to control the trajectories of the microrobots. Initial work on modelling the coil and microrobot behavior is reported along with simulation results for navigating one and two microrobots along independent desired trajectories. Qualitative results from a scaled-up printed circuit board version of the specialized substrate operating on permanent magnets are presented and offer proof-of-concept results for the approach. These tests also provide insights for practical implementations of such a system, which are similarly reported. The ultimate goal of this work is to use swarms of independently controlled microrobots in advanced, additive manufacturing applications.

A distributed market-based boundary coverage algorithm for multiple microrobots with network connectivity maintenance

In this paper, the boundary coverage of known environments is investigated using multiple microrobots (MMR) involved in a distributed inspection case study. A strong need for an operator is able to control and receive feedback from microrobots. However, communication range is limited because of the size effect of microrobot, and obstacles may also prevent microrobots from communicating. To enable MMR to accomplish coverage task while maintaining the network connectivity with a base station, we propose a market-based boundary coverage algorithm. This algorithm can dynamically allocate the boundary coverage task to a microrobot, so as to adapt to the change of communication network topology. A motion control model based on virtual spring–damper system is established to prevent communication network splitting by monitoring infrared link quantity information among microrobot nodes. Simulations and experimental results, obtained using our MMR tested in a distributed inspection case study, demonstrate that the proposed solution fulfills the objective of maintaining network connectivity at all times while completing the allocated boundary coverage task.

Independent control of multiple magnetic microrobots in three dimensions

A major challenge for untethered microscale mobile robotics is the control of many agents in the same workspace for distributed operation. In this work, we present a new method to independently control multiple sub-mm microrobots in three dimensions (3D) using magnetic gradient pulling as the 3D motion generation method. Motion differentiation is accomplished through the use of geometrically or magnetically distinct microrobots which assume different magnetization directions in a rotating or oscillating magnetic field. This allows for different magnetic forces to be exerted on each, enabling independent motion control and path following of multiple microrobots along arbitrary 3D trajectories. Path following in 3D with less than 310 μ m mean error is shown for a set of two microrobots of size 350 μ m and 1500 μ m, and independent motions are shown with three microrobots. It is also shown that control of more microrobots could be possible using improved magnetic coil hardware. Microrobot diversity is analyzed with regards to the effect on independent control. The proposed addressability method could be used for the 3D control of a team of microrobots inside microfluidic channels or in the human body for localized therapy or diagnostics.

Unknown Environment Mapping based on Multiple Micro-Robots

Unknown Environment Mapping based on Multiple Micro-Robots

Bio-inspired magnetic swimming microrobots for biomedical applications

Microrobots have been proposed for future biomedical applications in which they are able to navigate in viscous fluidic environments. Nature has inspired numerous microrobotic locomotion designs, which are suitable for propulsion generation at low Reynolds numbers. This article reviews the various swimming methods with particular focus on helical propulsion inspired by E. coli bacteria. There are various magnetic actuation methods for biomimetic and non-biomimetic microrobots, such as rotating fields, oscillating fields, or field gradients. They can be categorized into force-driven or torque-driven actuation methods. Both approaches are reviewed and a previous publication has shown that torque-driven actuation scales better to the micro- and nano-scale than force-driven actuation. Finally, the implementation of swarm or multi-agent control is discussed. The use of multiple microrobots may be beneficial for in vivo as well as in vitro applications. Thus, the frequency-dependent behavior of helical microrobots is discussed and preliminary experimental results are presented showing the decoupling of an individual agent within a group of three microrobots.

An overview of multiple DoF magnetic actuated micro-robots

This paper reviews the state of the art of untethered, wirelessly actuated and controlled micro-robots. Research for such tools is being increasingly pursued to provide solutions for medical, biological and industrial applications. Indeed, due to their small size they offer both high velocity, and accessibility to tiny and clustered environments. These systems could be used for in vitro tasks on lab-on-chips in order to push and/or sort biological cells, or for in vivo tasks like minimally invasive surgery and could also be used in the micro-assembly of micro-components. However, there are many constraints to actuating, manufacturing and controlling micro-robots, such as the impracticability of on-board sensors and actuators, common hysteresis phenomena and nonlinear behavior in the environment, and the high susceptibility to slight variations in the atmosphere like tiny dust or humidity. In this work, the major challenges that must be addressed are reviewed and some of the best performing multiple DoF micro-robots sized from tens to hundreds μm are presented. The different magnetic micro-robot platforms are presented and compared. The actuation method as well as the control strategies are analyzed. The reviewed magnetic micro-robots highlight the ability of wireless actuation and show that high velocities can be reached. However, major issues on actuation and control must be overcome in order to perform complex micro-manipulation tasks.

Control of Multiple Heterogeneous Magnetic Microrobots in Two Dimensions on Nonspecialized Surfaces

In this paper, we propose methods to control multiple untethered magnetic microrobots (called Mag-μBots), with all dimensions under 1 mm, without the need for a specialized surface. We investigate sets of Mag-μBots that are geometrically designed to respond uniquely to the same applied magnetic fields. By controlling the magnetic field waveforms, individual and subgroups of Mag-μBots are able to locomote in a parallel but dissimilar fashion. The control of geometrically dissimilar Mag-μBots and a group of identically fabricated Mag-μBots are investigated, and control strategies are developed for 1-D and 2-D motion. This is accomplished by learning the velocity response of each microrobot to various control signals and using the uniqueness of each microrobot response to achieve independent control. The effect of high-level control parameters are investigated in simulation and in experiments, and the simultaneous independent global positioning of two and three microrobots is demonstrated in 2-D space. As this control method is accomplished without the use of a specialized surface, it has potential applications in areas such as microfluidic systems and biomanipulation.

Congestion Avoidance for Multiple Micro-Robots Using the Behaviour of Fish Schools

This article summarizes a research topic which discusses one of the most common problems in multiple micro-robots' navigation, namely congestion avoidance. This situation occurs when troops of micro-robots moving in different directions meet each other at a common area causing congestion situations. To avoid this risky state - which can create an inextricable scenario - firstly, we established a local and a global communication network that manages the robots' displacement through formation control. This warns each of them of the existence of a risk of congestion and manages the choice of the priority group, which is a new concept that we introduce in order to deal with this kind of congestion conflict. Secondly, we consider a new algorithm based on chaotic equations and inspired by the behaviour of schools of fish, which solves the congestion problem by creating a bifurcation of the troop's configuration and enables the proper avoidance of the conflict exhibited by congestion.

Modeling and Control of a Continuum Style Microrobot for Endovascular Surgery

This paper presents a microrobot of continuum type that satisfies constraints in terms of degrees of freedom, size, and safety for endovascular surgery. The proposed instrument, which integrates multiple microrobots and a catheter, is called the Multi Active LInk CAtheter (MALICA). Its structure is redundant, compliant, and compact, which makes it a well-suited solution to control the catheter shape. In this paper, we focus on a single microrobot and its actuation to control the orientation of the catheter's distal extremity. The kinematic and differential kinematic models of the microrobot are developed. Because of its kinematic redundancy, the orientation control is formulated as an optimization problem. A differential model-based control scheme is proposed and experimentally validated.

Selective control method for multiple magnetic helical microrobots

Microrobots have been investigated in recent years with the objective of discovering applications in the biomedical industry. The selective control of multiple microrobots is a challenging task; however, such control would allow for the dexterous manipulation of microscale objects. In this paper, we present a novel control method for the selective actuation of microrobots using only an external magnetic field. Such selective actuation of microrobots can be achieved by combining two types of external magnetic field rotations and two microrobotic designs, one with a bar-shaped head and the other with a cross-shaped head. After the type of rotation is chosen, the bar-shaped or the cross-shaped head can be individually actuated or both of them can be actuated simultaneously. To demonstrate the feasibility of the proposed method, millimeter-sized prototypes were fabricated and their individual actuation was successfully demonstrated in silicone oil. The prototypes showed the ability to swim in silicone oil (viscosity: 100 cSt) with a synchronized frequency of up to 0.25 Hz. This result suggests that the proposed method can be used in water at high input frequencies while taking the scaling effect into consideration. Hence, this method is expected to have many practical applications.

Control methodologies for a heterogeneous group of untethered magnetic micro-robots

In this work, we develop methods for controlling multiple untethered magnetic micro-robots (Mag-µBots) without the need for a specialized substrate. We investigate Mag-µBots that are geometrically and magnetically designed to respond uniquely to the same input magnetic fields. Designs include: (1) geometrically similar Mag-µBots with different values of magnetization; (2) geometrically dissimilar Mag-µBots with similar magnetization; and (3) geometrically dissimilar Mag-µBots with dissimilar magnetization. The responses of both magnetically hard and soft Mag-µBots are investigated. By controlling the input magnetic fields, individual and sub-groups of Mag-µBots are able to locomote in a parallel fashion. Specifically, the magnitude and frequency of the imposed driving magnetic fields are used as selection methods among the Mag-µBots. Various methods for accomplishing motion discrimination are discussed, modeled, and tested. It is found that while fully decoupled control is not possible with this method, parallel actuation of sub-groups of Mag-µBots is possible and controllable.

Fast Visual Servoing of Multiple Microrobots using an FPGA-Based Smart Camera System

AbstractIn microrobotics, visual servoing is often the only way to track the position of a robot or manipulator. To allow for automated high-speed micromanipulation, reliable highspeed visual servoing systems are needed. This paper presents a smart camera implementation that is capable of tracking multiple microrobots with an accuracy below 2 μm inside a working range of 120 × 80 mm2using a state of the art CMOS vision sensor. The implementation of the tracking algorithm was partly carried out in hardware to allow for predictable signal latency and high update rate. The system is capable of tracking a single robot with an update rate of over 200 Hz.

2A1-N-082 XYθ型自走機械による精密ドリル加工システムの開発(マイクロナノ作業1,生活を支援するロボメカ技術のメガインテグレーション)

2A1-N-082 XYθ型自走機械による精密ドリル加工システムの開発(マイクロナノ作業1,生活を支援するロボメカ技術のメガインテグレーション)

2A1-3F-F8 遠隔制御された超小型ロボットによる微細加工搬送システム

本発表では, 複数の小型自走機械をインターネットを介して遠隔制御することで顕微鏡視野までの誘導を行い, その視野内においてマイクロドリルによる微細作業を実現するシステムの構築を行った結果について報告する。

The multi-agent system's design based on behavior-based on-line learning model

The central issue in the design of cooperative multi-agent systems is how to coordinate the behavior of the agents to meet the goals of the designer. Traditionally, this had been accomplished by hand-coding the coordination strategies. However, this task is complex due to the interactions that can take place among agents. Recent work in the area has focused on how strategies can be learned. Yet, many of these systems mainly put emphasis on the learning strategies of individual agent. So they suffer from the complexity, convergence and time-consuming problems and so on. This paper presents a novel learning method named Behavior-based On-line Learning on Multi-agent Domain. As tests bench a kind of multiple micro-robots soccer-playing system is built up in our laboratory. The construction of such experimental system involves kinds of challenges. In this paper we want to focus on how to evolve the coordination among agents automatically based on our new learning model. At first we give a brief introduce of our experimental system and present learning model in common sense, and then explain how to apply it to the experimental system. In end we will give some results showing that the proposed approach is feasible to guide the design of common multiple agents system.