Microrobot Research Articles

Sensitivity Ellipsoids for Force Control of Magnetic Robots with Localization Uncertainty.

The navigation of magnetic medical robots typically relies on localizing an actuated, intracorporeal, ferromagnetic body and back-computing a necessary field and gradient that would result in a desired wrench on the device. Uncertainty in this localization degrades the precision of force transmission. Reducing applied force uncertainty may enhance tasks such as in-vivo navigation of miniature robots, actuation of magnetically guided catheters, tissue palpation, as well as simply ensuring a bound on forces applied on sensitive tissue. In this paper, we analyzed the effects of localization noise on force uncertainty by using sensitivity ellipsoids of the magnetic force Jacobian and introduced an algorithm for uncertainty reduction. We validated the algorithm in both a simulation study and in a physical experiment. In simulation, we observed reductions in estimated force uncertainty by factors of up to 2.8 and 3.1 when using one and two actuating magnets, respectively. On a physical platform, we demonstrated a force uncertainty reduction by a factor of up to 2.5 as measured using an external sensor. Being the first consideration of force uncertainty resulting from noisy localization, this work provides a strategy for investigators to minimize uncertainty in magnetic force transmission.

Tailored Magnetic Springs for Shape-Memory Alloy Actuated Mechanisms in Miniature Robots

Animals can incorporate large numbers of actuators because of the characteristics of muscles; whereas, robots cannot, as typical motors tend to be large, heavy, and inefficient. However, shape-memory alloys (SMA), materials that contract during heating because of change in their crystal structure, provide another option. SMA, though, is unidirectional and therefore requires an additional force to reset (extend) the actuator, which is typically provided by springs or antagonistic actuation. These strategies, however, tend to limit the actuator's work output and functionality as their force–displacement relationships typically produce increasing resistive force with limited variability. In contrast, magnetic springs—composed of permanent magnets, where the interaction force between magnets mimics a spring force—have much more variable force–displacement relationships and scale well with SMA. However, as of yet, no method for designing magnetic springs for SMA-actuators has been demonstrated. Therefore, in this paper, we present a new methodology to tailor magnetic springs to the characteristics of these actuators, with experimental results both for the device and robot-integrated SMA-actuators. We found magnetic building blocks, based on sets of permanent magnets, which are well-suited to SMAs and have the potential to incorporate features such as holding force, state transitioning, friction minimization, auto-alignment, and self-mounting. We show magnetic springs that vary by more than 3 N in 750 $\mu$ m and two SMA-actuated devices that allow the MultiMo-Bat to reach heights of up to 4.5 m without, and 3.6 m with, integrated gliding airfoils. Our results demonstrate the potential of this methodology to add previously impossible functionality to smart material actuators. We anticipate this methodology will inspire broader consideration of the use of magnetic springs in miniature robots and further study of the potential of tailored magnetic springs throughout mechanical systems.

Development of Path Planning Algorithm of Centipede Inspired Wheeled Robot in Presence of Static and Moving Obstacles Using ModifiedCritical-SnakeBug Algorithm

<p>Path planning for a movable robot in real life situation has been widely cultivated and become research interest for last few decades. Biomimetic robots have increased attraction for their capability to develop various kind of walking in order to navigate in different environment. To meet this requirement of natural insect locomotion has enabled the development of composite tiny robots. Almost all insect-scale legged robots take motivation from stiff-body hexapods; though, a different distinctive organism we find in nature is centipede, distinguished by its numerous legs and pliable body. This uniqueness is anticipated to present performance benefits to build robot of the said type in terms of swiftness, steadiness, toughness, and adaptation ability.</p>This paper proposes a local path planning algorithm of multiple rake centipede inspired robot namely ModifiedCritical-SnakeBug(MCSB) algorithm. Algorithm tries to avoid static and dynamic obstacle both. The results demonstrate the capability of the algorithm.

Force characterization and analysis of thin film actuators for untethered microdevices

In recent years, untethered microdevices have drawn significant attention due to their small size, weight and their ability to exert forces without the need for wires or tethers. Such microdevices are relevant to implantable biomedical devices, miniature robotics, minimally invasive surgery, and microelectromechanical systems. While devices using these actuators have been widely utilized in pick-and-place and biopsy applications, the forces exerted by these actuators have yet to be characterized and analyzed. Lack of precise force measurements and validated models impedes the clinical applicability and safety of such thin film microsurgical devices. Furthermore, present-day design of thin film microdevices for targeted applications requires an iterative trial-and-error process. In order to address these issues, we present a novel technique to measure the force output of thin film microactuators. Also, we develop and fabricate three designs of residual stress microactuators and use them to validate this technique, and establish a relationship between performance and design parameters. In particular, we find an inverse dependence of the thickness of the actuator and its force output, with 70 nm, 115 nm and 200 nm actuators exerting 7.8 μN, 4.7 μN, and 2.7 μN, respectively. Besides these findings, we anticipate that this microsystem measurement approach could be used for force measurements on alternate microactuators including shape memory, piezo and electromagnetic actuators.

The Drone and the Honey Bee

While scientists rush to pin down the cause of colony collapse disorder and race to find a cure, engineers have wondered whether we might one day supplement real bees with mechanical ones. Called DelFly, a miniature robot has been built by an engineering team of the Micro Air Vehicles Laboratory at Delft University of Technology in the Netherlands. The engineers there have various practical applications in mind. For example, when perfected, the bots could flit around greenhouses spotting diseases with their cameras. The robots could also be fitted with apparatuses to perform an even more vital and insect-like task—pollinating crops.

Single‐Crystalline Vanadium Dioxide Actuators

AbstractActuators that convert other forms of energy to mechanical energy have attracted extensive interest for their critical applications in microelectromechanical systems and miniature robotics. Recently, it is discovered that vanadium dioxide (VO2)‐based microscale bimorph actuators demonstrate comprehensive superiority of actuation performances, taking the good of the giant theoretical power density (7 J cm−3) and ultrafast response (∼picosecond) of crystalline VO2, while they still suffer from the intrinsic shortcomings of complex structures. Here, “single‐crystalline VO2 actuators” (SCVAs) that have unique self‐bending behavior upon temperature change are reported. This is realized by facilely and precisely controlling the phase structures via lateral stoichiometry‐engineering in VO2 nanobeams at the nanoscale level. These SCVAs exhibit remarkable actuation performances and admirable stability, which are equivalent or even superior to the reported VO2‐based conventional bimorph actuators. It is noteworthy that the gradual, reversible, and predictable bending of SCVAs enables a precise actuation control of related mechanics, such as the quantitative wind detector and thermal micromechanical claw. This work demonstrates the possibility of this strategy to enable single crystalline actuators excellent performance by internally lateral and gradual strain‐engineering.

Structure of nanocardboard could improve microrobotics

Structure of nanocardboard could improve microrobotics

Intelligent Autonomous Pollination for Future Farming - A Micro Air Vehicle Conceptual Framework With Artificial Intelligence and Human-in-the-Loop

Food security is one of the societal challenge topics. As one-third of all food consumed by humans relies on animal pollination currently, this research provides an emerging solution to food supply reduction caused by population shrinking of natural pollinators, so as to reduce its impact on ecological relationships, ecosystem conservation and stability, genetic variation in the crop plant community, floral diversity, specialisation and evolution. This paper develops a conceptual technical roadmap of autonomous pollination for future farming using robotic micro air vehicle pollinators (MPrs). The research provides new insights into autonomous design and manufacture and into possible ways to increase the production efficiency which shortens the time from lab to market. The autonomous MPrs are realized using artificial intelligence and human expertise in the loop for smart agricultural industry. Further, this work identifies scientific and technological advances that are expected to translate, within proposed regulatory frameworks, into the pervasive use of MPrs for agricultural applications and beyond.

The Survey of CNN-based Cancer Diagnosis System

This thesis summarizes the structure and image processing methods of miniature robot from the perspectives of miniature diagnostic robot, CSF (CNN-SVM-FCN) and expert systems, in which it highlights the key technologies and the latest research progress in various aspects, analyzes the advantages and disadvantages of each method, elaborates their respective implementation processes and system framework. It also further explores ways to promote their complementary advantages and makes a prediction of the possible opportunities brought by the combination of these three methods.

It's a bug's life as a maintenance engineer [aircraft engine maintenance

The imperatives for any aircraft are that it has to be safe and available. In these respects the aircraft is only as good as its engines. Some collaborative work based on miniature robotics is looking at how these engines can be kept in good working order.

Structure design of a miniature and jumping robot for search and rescue

The extremely dangerous and complex environment caused by tremendous earthquakes or unnatural disasters usually brings great danger to survivors and salvagers. Therefore, search and rescue missions after any disaster indicate a huge need in special access to reduce the loss for human beings and, at the same time, to improve the capability of performing the tasks. In terms of the miniature robots which can go into the confined zone for the searching tasks, this project focuses specially on analysing climbing obstacle capability of the miniature robots, and introduces a new concept composed of a jumping robot which is mounted on a tracked mobile base. To design, calculate, and analyse this system, an appropriate mechanism, geometric dimensions, and specific properties are detailed, which include a dual-tracked articulated transformable locomotion system, a transmission system with a sleeve shaft, an incomplete gear jumping mechanism, and the selection and calculation of power system motors. To complete the design procedure, a three-dimensional sketch of each component of the robot was generated by means of Solidworks.

Design of a miniature modular inchworm robot with an anisotropic friction skin

SUMMARYThis paper presents the design, analysis, and experimental validation of a miniature modular inchworm robot (MMIR). Inchworm robots are capable of maneuvering in confined spaces due to their small size, a desirable characteristic for surveillance, exploration and search and rescue operations. This paper presents two generations of the MMIR (Version 1—V1 and Version 2—V2) that utilize anisotropic friction skin and an undulatory rectilinear gait to produce locomotion. This paper highlights design improvements and a multi-body dynamics approach to model and simulate the system. The MMIR V2 incorporates a slider-crank four-bar mechanism and a relative body revolute joint to produce high-frequency relative translation and rotation to increase forward velocity and enable turning capabilities. Friction analysis and locomotion experiments were conducted to assess the systems performance on various surfaces, validate the dynamic model and simulation results, and measure the maximum forward velocity. The MMIR V1 and V2 were able to achieve maximum forward velocities of 12.7 mm/s and 137.9 mm/s, respectively. These results are compared to reported results of similar robots published in the literature.

Mobile robot location algorithm based on image processing technology

To improve the reconfigurable micro mobile robot cluster system based on precision detection, a positioning and tracking system based on computer digital image processing technology was developed. The system consisted of three subsystems: image acquisition and preprocessing subsystem, rapid positioning subsystem based on robot marker recognition, and tracking subsystem based on position estimation. First, after studying the related algorithms in the subsystem, the threshold selection method of adaptive gray weight conversion was proposed for image preprocessing. Then, a fast positioning method based on marker recognition for miniature mobile robots was proposed. The selection of micro-robot markers and the basis for judging the selection of moments were given. A triangular projection positioning method was implemented, and related experimental results were given. Finally, the windowing scanning algorithm was optimized. According to the speed and direction of the robot, a tracking algorithm for position estimation was proposed. Through the simulation experiment, the effect of system positioning tracking and the system reference time in 0.270 s were given. The results showed that the system had high real-time performance.

A Magnetic Manipulator Cooled With Liquid Nitrogen

Miniature robots manipulated by external magnetic fields could enable less invasive surgeries. Magnetic tools, capsules, or medication can be controlled inside a human body using electromagnets. However, resistive magnetic devices able to produce strong magnetic fields in a large volume inefficiently use space and energy. This letter presents the design and testing of a magnetic manipulator cooled with liquid nitrogen. This technique reduces the electrical resistance of copper wires. It, therefore, reduces the amount of heat generated to produce a given magnetic field. Liquid nitrogen-cooled electromagnets are smaller than air-cooled ones and use less power. This letter examines how both effects scale with the size of the workspace. The system presented possesses six electromagnets and its ability to control a robot is demonstrated experimentally.

Untethered Miniature Soft Robots: Modeling and Design of a Millimeter-Scale Swimming Magnetic Sheet.

The actuation and control of miniature soft robots are challenging problems due to their limited onboard space and flexible bodies. Smart magnetic materials are promising candidates to address these challenges since they can be powered and guided remotely by magnetic field for functionalities, such as swimming, grasping, and pumping. In this study, we program an undulatory swimming gait into a small rectangular sheet that is made of a flexible magnetic homogeneous composite. The sheet bears a sinusoidal magnetization profile throughout its body and deforms into undulatory shapes in a rotating uniform magnetic field that aligns with its length. The traveling wave-like deformation of the sheet interacts with the surrounding liquid and propels the sheet in a bidirectional nonholonomic swimming gait. Previous studies on this sheet were not able to model the deformation accurately or characterize the swimming systematically due to a lack of understanding of the underlying physical principles involved. For the first time, we develop a model from underlying physical principles to explain and predict the sheet deformation, which enables it to swim at air-water interfaces and generate propulsive forces under water with an additional stiff frame. The swimming capability and maneuverability of the millimeter-scale sheet are demonstrated in experiments, and its swimming performances in various scenarios are characterized quantitatively. The soft swimming sheet can potentially be used for microrobotic tasks, such as delivering cargo or transporting individual cells in poorly accessible workspaces.

Light-Driven Micro/Nanomotor for Promising Biomedical Tools: Principle, Challenge, and Prospect.

A micro/nanomotor (MNM), as miniaturized machinery, can potentially bridge the application gap between the traditional macroscale motor and the molecular motor to manipulate materials at the cellular scale. The fascinating biomedical potential application for these tiny robots has been long envisioned by science fiction, such as "Fantastic Voyage", where complicated surgery can be performed at single cell precision without any surgical incision. However, to enter the highly conservative biomedical and healthcare industry in practice, the MNM must provide unique advantages over existing technology without introducing additional health risk, which has not been fully materialized. As an emerging approach, light-driven micro/nanomotors (LMNMs) have demonstrated several unique advantages over other MNMs, which will be addressed in this Account. As a control signal, light promises additional degrees of freedom to manipulate MNMs by modulating the light intensity, frequency, polarization, and propagation direction with spatial and temporal precision, which enables excellent controllability and programmability of LMNMs. Additionally, the fruitful knowledge and catalysts from the well-studied photocatalysis can be readily transferred to LMNMs for photoelectrochemical reactions, which provides a rich materials inventory for the development of advanced LMNM systems. A model LMNM in general can be regarded as a miniaturized solar cell combined with electrokinetic propulsion parts, where electric current is provided by the photovoltaic effect and then converted to propulsion thrust through a variety of electrokinetic mechanisms. It can be envisioned that the electric current may be further regulated with the onboard electronic circuit for advanced logic-controlled nanorobots. Finally, because incident photons instead of active chemicals provide the energy for LMNM propulsion, the highly active but toxic chemical fuels can be avoided, which suggested their better biocompatibility. It is essential to emphasize that all of these promises rely on the in-depth understanding of the photoelectrochemical reaction as well as the physics of electrokinetic phenomena, which requires further investigations. As a persistent endeavor, the biomedical application is the most attractive but challenging target for MNMs. Currently, most of the MNMs are demonstrated with in vitro conditions largely deviating from the biological environment, and nontrivial in vivo studies and cytotoxicity experiments are rarely reported. As merits of MNMs, the efficiency, biocompatibility, ion tolerance, and controllability critically determine the future success of MNMs. In this Account, existing and prospective solutions in these aspects are systemically discussed for light-propelled MNMs. We believe that, with a better understanding of the fundamental photoelectrochemical and electrokinetic processes, the development of motor design strategies, and improved fabrication methods, the promised practical biomedical application, such as early disease diagnosis, interventional therapy, targeted therapy, and microsurgery, could be realized in the near future.

Harmonious Cable Actuation Mechanism for Soft Robot Joints Using a Pair of Noncircular Pulleys

Various slim robots, such as surgical robots or humanoid robot fingers, are remotely actuated using transmission cables. If pull–pull drive is applied to actuate them using circular driving spools regardless of the shape of the joints, the tension of the driving cable becomes difficult to be maintained properly. Fortunately, it is possible to solve such a cable slack problem by providing an appropriate cable actuation length to the joint structure of the robot from the cable driving unit. Therefore, we propose a harmonious nonlinear cable actuation mechanism suitable for driving noncircular shaped joints. The proposed cable driver can mechanically provide the required cable actuation length to suit the angle change of the target joint using a pair of noncircular pulleys without increasing the number of actuators. In this paper, a design methodology of a noncircular pulley that can be applied to pulleyless rolling joints (PR joints) as well as pulleyless hinge joints is shown. Moreover, a practical cable driver is designed for actuating a hyper-redundant discrete bending joint composed of PR joints, and its effectiveness is verified through experiments. This novel cable actuation mechanism using noncircular pulleys or gears is expected to be applicable to various miniature robots such as surgical robots and animal robots of continuum structure in the future.

Multi-axial non-contact in situ micromanipulation by steady streaming around two oscillating cylinders on holonomic miniature robots

In the field of micromanipulation, an in situ three-axial rotation of a microscale object remains difficult to realize, with rotational resolution and repeatability remaining low. In this paper, we describe the fundamental principle, properties, and experimental results of multi-axial non-contact in situ micromanipulation of an egg cell driven by steady streaming generated around an oscillating cylinder. A continuously oscillating cylinder generates the steady streaming that draws an egg cell toward the cylinder. If it is trapped by an eddy near the tip of the cylinder, it continuously rotates around the vertical axis at a fixed point. If it is trapped by a swirl flow generated around the side of the cylinder, it rotates around the horizontal axis. We define Reynolds number, Re, as arcω/ν, where a is half of the oscillation’s amplitude, rc is the cylinder’s radius, ω is the oscillation’s angular frequency, and ν is the kinematic viscosity. We demonstrate that the conditions of the vertical and horizontal rotations are determined by two dimensionless numbers: Re and a/rc. In our experiments, we obtained rotational resolutions of 0.05° and 0.11° and maximal angular velocities of 34.8°/s and 188°/s for the vertical and horizontal rotations, respectively. We also developed unique micromanipulation methods using two oscillating pipettes attached to holonomic miniature robots. We successfully manipulated five degrees of freedom (DoF) of the cell (three posture angles and two translational displacements along the X and Y axes) with the steady streaming. The proposed method enables a multi-axial, non-contact, in situ, and compact micromanipulation independent of the electrical, optical, magnetic, shape, and stiffness properties of the objects; moreover, it can be applied in microfluidics, biomedical, and heterogeneous microassembly applications.

Studying the Dynamics of Miniature in-Pipe Vibration Type Robots

Actual problem is the study of oscillation acting on functional characteristics of miniature robots based on frequency modulation and changing of pulse recurrence frequency. Such robots are the systems with electromagnetic action, investigation of which is performing in many scientific centers of the world. Study of oscillation processes satisfy the receiving of relationships between functional and frequency characteristics, determine conformity working and required parameters and to extend robot's possibilities. Miniature robots with electromagnetic drive system and technological on board sensors are intended mainly for direct or inverse motion inside of pipes with small diameter (5-20 mm) and analyze of the quality internal surfaces of the pipes, for nondestructive testing and other inspection operations in energy, nuclear power stations for example, in aviation and space technologies. In this paper the motion equations of electromagnetic in-pipe robot are presented, as so as nomographs and characteristics, those may use under design of miniature robots for the purposes of target applications. The results of investigations of oscillatory processes in miniature in-pipe robots of the electromagnetic principle of action are presented. Robots are equipped with coupling devices with internal surfaces of small diameter pipes. Dependences of the robot's parameters on the frequency, length and duration of the control pulses are given. The oscillations effects for a different frequency on the characteristics of the robot with the possibility of reversible motion when moving in media of different viscosities are analyzed.

Macro–micromanipulation platform for inner ear drug delivery

This paper describes the pulling and steering of magnetic therapeutic microparticles for drug delivery based on a macro–micromanipulator system. The macromanipulation system is composed of a 6 Degree Of Freedom (6 DOF) serial manipulator while a linear permanent-based actuator (1 DOF) is equipped at the end-effector as a micropart to precisely steer and pull magnetic microparticles. Using the classical mathematical tools of robotics, we developed the global kinematic model of the robot-device assembly, thus defining a reference trajectory to propel the microparticles. A novel actuator-based permanent magnet has been designed and realized as a robot micro end-effector to control the trajectory of a microparticle along a millimeter-sized workspace. Simulations and experiments were conducted to show the ability of the macro–micromanipulator system to steer particles on a viscous fluid simulating a biological media.