In this paper, we describe design and experimental results of repetitive calibration of an holonomic inchworm robot based on an inverse trajectory analysis of a tip of a probe for microscopic operations. The mobile robot has two U-shaped electromagnets and four piezoelectric actuators (PAs) for obtaining 3-degrees-of-freedom (3DoF) motion on well-polished ferromagnetic surfaces. We have proposed the kinematic model to get relationship among four input voltages to PAs and three displacements of the robot at a half step. We have also solved the inverse trajectory analysis of the probe to convert the motion errors of the probe into those of the robot. Moreover, we have proposed repetitive calibration formulas to calibrate 3DoF motion of the probe under a microscope simultaneously. In experiments, we have checked that the proposed formulas are surely working for decreasing the motion errors at straight motion although rotation around the tip is hard to calibrate because of its posture measuring error of an image processor. We discuss compact and flexible microscopic operations.

In this paper, we describe design and development of a 3-axis proportional-integral-derivative (PID) controller for a holonomic precision inchworm robot. The mechanism has two Y-shaped electromagnets and six piezoelectric actuators (PAs) for obtaining 3-degrees-of-freedom (3DoF) motion on well-polished ferromagnetic surfaces. To measure its 3DoF position simultaneously, an integrated 3DoF inner position sensor composed of 4 linear encoders are developed. In experiments, we have checked that this arrangement of the encoders is valid for measuring the 3DoF motion under a condition without disturbance. To be robust against the disturbance, we also discuss requirement of an acceleration feedforward controller with 3 motion sensors to detect disturbance and slips of supporting electromagnet. This paper is first article which demonstrates simultaneous 3-axis PID control with nanometer-scale positioning resolution of miniature mobile robot driven by PAs. We also discuss about the future direction of the realization of compact, precise, fast, flexible, and energy-efficient mobile robotic factory.

In this paper, we modeled and analyzed the shape-memory-alloy (SMA) heat engine in steady state. The heat engine is composed of two pulleys, three gears, and an SMA coil spring. We formulated an expression that optimizes the relationship among the parameters for the maximum power and the torque of the heat engine. This article is the first to present the basic procedure to solve the optimal solution for the pulley-gear-type heat engines that are driven by an SMA coil spring. We also discuss the miniaturization of the heat engine to actuate the Bio MEMS and the micro TAS devices as fluidic MEMS actuators.

In this paper, we describe a newly proposed design of an integrated three-degrees-of-freedom (3DoF) inner position sensor for an omnidirectional and holonomic inchworm mobile mechanism. The mechanism has two Y-shaped electromagnets and six piezoelectric actuators for obtaining 3DoF inchworm motion on well-polished ferromagnetic surfaces. We calculate conversion equations from four measured distances to X-, Y-, and θ-axis motion. We also explain how to make the input signals to realize the minimum time trajectory of free electromagnets with a newly proposed special kinematic model as an additional condition for energy-efficient control. Details of the design and performance are also described to realize flexible, compact, and high-accuracy positioning in precision engineering.

In this paper, we have described newly developed wet tweezers based on capillary force for micro-assembly of complex-shaped objects. The tweezers are composed of two movable rods driven by a piezoelectric linear motor and two thin tubes. The two rods penetrate the liquids in the thin tubes. If we simply stamp the rods on a base, we can apply a drop of even high viscosity liquids. If we contact them to an object, we can pick it up by capillary force. Because we use the pair of the rods for picking up, posture of objects are fixed. That is important for accurate micro-assembly. To investigate generative force of the wet tweezers, we study relationship among viscosity, surface tension, and shape of meniscus of the liquid. We also formulate the capillary force as a function of gap distance between the rod and the object with three different liquids. In several experiments, we have confirmed the wet tweezers have good assembling accuracy and possibility to realize heterogeneous and complex-shaped micro-assembly.

In this paper, we describe the design and development of the newly developed 3-DOF inchworm mechanism with 6 contact points on a surface to improve a positioning repeatability. The mechanism consists of a pair of Y-shaped electromagnets and six piezoelectric actuators and moves like an inchworm. We calculate a 3-DOF simple harmonic vibration model to get input signals in any 3-DOF motions. In several experiments, we confirm that the mechanism has better positioning repeatability than in previous mechanisms with 4 contact points, especially when the mechanism carries a payload. The design details and basic performance are described to contribute to flexible precise positioning technology.

In this paper, we describe the dynamical analysis and improvement of velocity for a precise inchworm mechanism with 3 DOF. This mechanism is composed of 4 piezoelectric actuators and pair of electromagnets and moves like an inchworm with less than a 10 nm resolution. We calculate the dynamical relationship between 3 DOF motion and 4 piezoelectric displacements. We also calculate the maximum velocity with no slip of electromagnets because the no slip condition is very important for motion repeatability. In several experiments, we have checked the theoretical validity and we confirm that the analysis procedure works well as an initial design of the inchworm mechanism. The design procedure, basic performance, and chip-mounting applications are also discussed as an advance in the new field of micro-robotics used in precision regions.

In this paper, we describe development of the multi-axial micromanipulation organized by versatile micro robots using micro tweezers. To conduct microscopic operations, a unique locomotion mechanism composed of four piezoelectric actuators and two electromagnets is proposed. Here two legs arranged to cross each other are connected by four piezoelectric actuators so that the robot can move in any direction, i.e. in X and Y directions as well as rotate at the specified point precisely in the manner of an inchworm. To manipulate micro objects by these versatile micro robots, we have developed micro tweezers driven by 3 piezoelectric actuators. We have also developed an electromagnetic spherical micromanipulator to position the micro tweezers. The electromagnetic spherical micromanipulator rotates in yaw, roll and pitch directions independently. The electromagnetic spherical micromanipulator is a 1-inch cube size, so we can easily attach them on top of the versatile micro robots. We have developed the multi-axial micromanipulation organized by 3 versatile micro robots with the electromagnetic spherical micromanipulator and micro tweezers. The whole manipulation device is very small, 200 mm in diameter and 70 mm in height, so we can easily attach the device to micro processing instruments even if the working area is very small. This device has 21 DOF with less than 100 nm resolution. In experiments, we have demonstrated flexible handling of miniscule glass spheres with a diameter of 20 mum. We have also succeeded in fixing miniscule glass spheres on a sample table by an ultraviolet cure adhesive. The design procedure, basic performance and micro-assembling applications of this tiny robot are also discussed as part of the new field of micro robotics requiring especially high precision in certain regions.

In this paper, we describe the design and development of a positioning and compensation device for a versatile micro robot. To provide microscopic operations, the versatile micro robot has developed. The robot can move in any direction in the manner of an inchworm. However many positioning errors exist because of an assembling error in the four piezoelectric actuators and two electromagnets. We need an automatic positioning device for more accurate work. Motion compensation is also highly required for more effective work. This robot is very small, so it can easily be set to work with the various devices. The positing device should also be small so that we can carry the device easily and set it up in a narrow working area. In this report, we propose a USB camera based positioning device with special compensation function. In experiments, we succeeded in controlling the robot on an octagonal path with controlling the posture angle freely. When we compensate for the motion, the positioning time becomes 60 % compared to that of no compensation. The design procedure, basic performance and biomedical application are also discussed as an advance in the new field of micro-robotics used in precision regions.

In this paper, we describe the newly-developed microscopic operation system assisted by one cubic inch sized micro robots under an inverted microscope. These micro robots, which are composed of piezo elements, are capable of moving in any direction, i.e. in X and Y directions as well as precisely rotate at the specified point. And they can convey several surgical fine tools such as a holding pipette and injection pipette so that they can execute flexible operations in a bio-cell while the well-trained operator can conventionally manage this operation. To automate these operations in the bio-cell, the tiny robots can be navigated and positioned by the combination of two styles of coordination measurement. At first as a coarse navigation manner, several micro robots can be guided into the range of the microscope from the arbitrary positions based on the analog signal feedback used by a PSD sensor. And then the microscopic operations can be carried out by monitoring the position of fine tools by analyzing the microscopic images obtained from the CCD camera. The experimental results show that the proposed system succeeds in maneuvering these small robots to provide microscopic operations.

We describe the newly developed flexible micro processing system assisted by 1 inch size robots in the scanning electron microscope (SEM). The basic performances of the small robot composed of piezo-elements and electromagnets are presented and then the magnetic shield property is considered to prevent the SEM image distortion due to magnetic flux. In order to handle some small objects, an electrostatic micromanipulator driven by the piezo-bimorph is also incorporated on the robot. The small sliding table on the robot can transport them at SEM focusing point accurately. This arrangement can allow the X-Y accurate positioning at any location within the chamber. On the sample table, a micromanipulator from another small robot can pick up and down the small objects simultaneously. In addition, the fiber guided YAG-laser is also employed to provide the micro-material abrasion. The operator can control each small robot easily with the help of the real time monitoring of SEM image and the PC assisted interface.