This paper presents the design, and control of a sensorized microgripper using VCM (voice coil motor). In order to increase the sensitivity of the sensorized microgripper, shape design and determination of sensor position are performed using finite element analysis. Micro EDM (electric discharge machine) and wire cutting technique are employed to fabricate the microgripper. Empirical model of the microgripper is achieved to analyze the performance and to control the position and gripping force. By using this identification model, both the perfect tracking controller (PTC) for the position control, and the adaptive zero-phase error tracking controller (ZPETC) for the force control are implemented. The effectiveness of the proposed model-based control method is verified by both simulation and experimental studies. Simulation and experimental results show that the proposed control method can be effectively applied to improve the motion tracking performance. Especially, in case of force control to grip and manipulate soft materials such as biomaterials and tissues, the proposed controller can be very useful to prevent the invasion of the target material by excessive force.

In this paper, we present a novel integrated bio cell processor to handle individual embryo cells. Its functions are composed of transporting, isolation, orientation, and immobilization of cells. These functions are essential for biomanipulation of single cells, and have been typically carried out by a proficient operator. The purpose of this study is the automation of these functions for effective cell manipulation using a MEMS based bio cell processor. This device is realized with relatively simple design and fabrication process. To transport cells, microfluidic channel is employed. The isolation of a cell is performed by actuation of polypyrrole (PPy) valves. The orientation control of cells is accomplished by dielectrophoresis (DEP). By the suction from the micro-hole, the target embryo cell is immobilized. Experimental results show that this device can substitute the essential but very tiresome and repeatable embryo cell manipulation and contribute significantly to the improvement of speed and success rate of operation by facilitating the cell manipulation. The cell viability test for the device is studied through the distribution of mitochondria in mouse (B6CBA) embryo cells and cultivation of cells for 86 h after cell was manipulated by DEP.

An adaptive accommodation control for complex assembly (CA) is presented. The CA is defined as a task whose assembled parts have complex geometry including concavity. The concept of the adaptive accommodation, which is inspired by the insertion operation of a blindfold human, is to adaptively change the accommodation property depending on the sensed contact wrench and the current target twist. Both the bounded wrench condition and the target approachability condition can be satisfied simultaneously by applying the adaptive accommodation control law. By using the convex optimization technique, an optimum target approaching twist with adaptive accommodation properly can be determined at each instantaneous contact state as a global minimum solution. A new adaptive accommodation control law, which is independent of part geometry, is developed without motion planning nor contact analysis procedure. A VME-bus based real-time control system is built to various CA tasks experiments.

Presents a target approachable force-guided control for complex assembly. A complex assembly (CA) is a task which deals with complex shaped parts including concavity or whose environment is so complex that unexpected contacts occur during insertion. CA tasks are encountered frequently in manufacturing automation and robot applications. To make CA successful, both the bounded wrench condition and the target approachability condition should be satisfied simultaneously during insertion. The former can be satisfied by properly designing the damping control parameters, and the latter by determining an admissible twist minimizing the difference between the current and the target direction. By applying the convex optimization technique, the target approachable twist can be determined at each instantaneous contact state as a global minimum solution. Incorporated with an admissible perturbation method, a new CA algorithm using only the sensed resultant wrench and the target direction vector is developed without motion planning nor contact kinematic analysis procedure, which requires the geometry of the part and the environment. As a result of the simulation for the task of inserting a T-shaped object involving concavity, its feasibility and applicability have been verified The task of inserting a T-shaped part into a slot with a tight tolerance was successfully executed by the proposed target approachable force-guided controller.

This paper presents a compliant control method for insertion of complex objects with concavities. Most work on robot assembly using compliant motion control focuses on overcoming jamming conditions for simple peg-in-hole problems, and cannot be used for complex shapes frequently encountered in assembly applications. When an object is being inserted into a hole or slot with a small clearance, a contact path issued to compensate for uncertainties. When the object shape is complex, however, the contact state changes several times and severely, making compliant control difficult. Our algorithm is capable of controlling compliant motion in spite of changing contact states. During the execution of a nominal motion plan, it computes the actual position of the contact point from the force/torque sensor reading using a contact localization algorithm. It then dynamically updates the center of compliance to the computed contact point, and minimizes the chance of jamming and unwanted collisions. The control scheme has been implemented on hardware and tested on the task of inserting a T-shape into a C-shape involving a very tight tolerance. The insertion motion was accomplished by a sequence of 2 translational and 1 rotational compliant motions, and successfully executed by the proposed compliant motion controller.