Research Targets

Insects and microorganisms show high athletic performance and have various sophisticated sensors, although they are often simple structures. The purpose of this laboratory is to develop small creative mechanisms, from cm to sub micrometer size, for actuating micro objects and sensing physical quantity. Fig.1 shows the target size for research and development. We have targeted the phenomena in the microscopic region through experiments and scientific analysis. We have also demonstrated our developments with their new benefits, such as lightweightness, small size, high sensitivity, cost-saving, energy efficiency and environmentally-friendly performances, through publications, presentations, and exhibitions.

Fig.1

Research Project from 2008 to 2012

<Title>
"Development of versatile miniature robots with micro/nano processing"

The final goal of this project is to develop an ultra-precise and flexible production system, which we call:, an “Intelligence Micro Robots Factory”, organized by insect-sized “Versatile micro robots” which move 3 DOF independently with less than a 10 nm resolution.

Our latest research topics are as follows.
1.Dynamics analysis of the Versatile miniature robot
2.Improvement of velocity and motion repeatability
3.Repepetive motion compensation
4.Visual feedback under microscopic image
5.Design and development of the fine tools for chip mounting and egg-cell processing

We have also developing two test benches for an "Intelligence Microrobot Factory".

6.Bio-medical application
Automatic egg-cells injection with feeding, gathering, holding, and rotating functions
7.Industrial assembling application
Compact chip-mounting organized by versatile miniature robots with various fine tools

Part of this study was supported by the "Promotion of Environmental Improvement for the Independence of Young Researchers" under the Special Coordination Funds for Promoting Science and Technology from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan.

A Versatile Miniature Robot

Fig.2 shows the structure of the precise miniature mechanism with 3 DOF. Two closed loop electromagnets, EM-1 and EM-2, arranged to cross each other, are connected by four piezoelectric actuators, PZT-F, PZT-B, PZT-R, and PZT-L, so that the mechanism can move precisely in any direction in the manner of an inchworm. As shown in Fig.3, the mechanism can move in X and Y directions as well as rotate at the specified point precisely in the manner of an inchworm. This small mechanism can move flexibly and widely on the well-polished iron surface. Fig.4 shows the photographs of mechanisms. The “G” type is the latest version. Table 1 shows the movement of coarse motions. Table 2 shows a typical performance of the G-type mechanism. Fig.4 shows the experimental result of 25nm step motion. We have improved this mechanism using dynamical analysis to improve motion performance as shown in fig.5. Improvement of repeatability is one of the most important points for industrial application; therefore we continue to improve the mechanism and the precise measuring device.

Fig.2

Fig.3

Fig.4

Table 1
Movement Type Driving Frequency
Amount of data
Combination of translational motions G 100 4Mbyte
Arc Trajectory T 100(3 times faster than original) 1Mbyte
Rotation G 100,200 4Mbyte
Orthogonal G 100,200 7Mbyte
Diagonal straight motion G 100,200,300 6,7,4Mbyte
Table 2
Performance of versatile miniature robot (G type)
Maximum velocity 23 mm/s
Frequency 0 to170 Hz
Movable load 120 g
Resolution less than 50 nm
Movable area 30cm x 30cm
Size 50mm x 50mm x 25mm
Weight 60g

Fig.4

Fig.5

[Research topics]
1.Computer simulation for dynamic motion
2.Development of precise distance sensor to measure relative movement between two electromagnets in X, Y, and rotational axes
3.Improvement of durability
4.Improvement of stability with various loading conditions
5.Analysis of magnetic circuit to increase the ratio of magnetic force to mass
6.Waveform optimization and analysis of the slip-based locomotion method

Compensation and Navigation

We have developed the CCD-camera-based positioning device as shown in Figs. 6 and 7. This device also has a compensation function that can control the robot more efficiently. Fig. 8 shows the principle of repetitive compensation. As shown in Figs. 9 and 10, we confirmed that we could compensate the robot motion very well. We have also developed navigation for 3 robots. Fig. 11 shows the sequential photograph of 3 robots' navigation in order to gather 3 tool tips in a very limited area. This function is important when we conduct microscopic operations because the size of the microscopic image is very narrow.

Fig. 6

Fig. 7

Fig. 8

Fig. 9

Fig. 10

Fig. 11

[Research topics]
1.Improvement of compensation functions
2.Study and analysis of relationship between durability and motion performance
3.5 robots' navigation

Cell Processing with multi-functions

Figs. 12 and 13 show a system configuration for cell processing. Precise miniature robots with various functions are put on the table of an inverted microscope. These robots are manually controlled by a joystick or automatically controlled by visual feedback of the microscopic image. Because each robot is very small, 3cm-cubed and 50g, we can use 6 robots on a conventional microscopic table, 20cm squared, simultaneously, without special reparation of microscopy. Even if we use conventional manipulators for injection, robots can still provide additional functions, such as “rotation”, “feeding”, and “gathering”, to support injection by conventional manipulators. Some interesting applications have been proposed and demonstrated. Figs. 14 and 15 show automatic egg-cell gathering supported by visual feedback. Another interesting application, 4 pipettes processing, as demonstrated by joystick control, is depicted in Fig. 16. We are now developing automatic processing organized by 5 pipettes as depicted in fig. 17. This unique concept combines various functions, such as rotation, gathering, feeding, injection, and holding and carrying to improve the efficiency of cell processing.

Fig. 12

Fig. 13

Fig. 14

Fig. 15
MOVIE 10Mbyte

Fig. 16
MOVIE 2.5Mbyte, 3 times faster than original

Fig. 17

[Research topics]
1.Automatic control of 5 pipettes by visual feedback
2.Compensation of pipette motion by using the microscopic image of pipette tip
3.Development of a small pump for feeding & gathering pipettes
4.Stokes flow analysis of viscous local flow around vibrated pipette by fluid dynamics and FEM analysis

Chip mounting organized by versatile miniature robots with fine tools

Recently, the miniaturization of portable device and that of electronic parts has become remarkable. Chip capacitance has already reached 0402 (0.4mm x 0.2mm) size and 1mg. Moving stages inside conventional chip-mounting devices are more than 100kg and big vibrations occur on the precise instruments around them, although electronic chip parts themselves are less than 1mg. The final goal of this study is the development of the low-vibration, low-power and low-floorage mounting devices supported by versatile miniature robots with compact chip-mounting tools. Fig. 18 shows a conceptual image of this project. Fig. 19 is the research strategy. The design procedure, basic performance and micro-assembling applications of these tiny robots are also discussed as part of the new field of micro-robotics requiring especially high precision in certain regions.

Fig. 18

Fig. 19

[Research topics]
1.Navigation of 9 robots at coarse and micro-region by visual feedback of CCD cameras
2.Fast positioning: less than 2 cm distance with 1 μm accuracy
3.Development of compact chip-mounting device using micro-viscous flow