A micromachined pressure sensor that is suitable for integrating on the tip of the grasper of an endoscopic surgical instrument is presented. Device operation to detect the pressure applied on the body tissues during endoscopic surgery is based on the change in the capacitance between a 5 micrometers thin boron doped silicon membrane and 1 micrometers thick Aluminium electrodes sputtered inside 15 micrometers deep cavities etched in glass. The design, structural optimization for obtaining high sensitivity and the fabrication process for the device are presented. The device has a peak sensitivity of 500 pFmm2/N. The range of the pressure sensor is from 0.01 N/mm2 up to 0.1 N/mm2 which is suitable for measuring the pressure on various tissues inside the body during endoscopic surgery. Since the device simulates the teeth like surface of the existing grasper it is possible to integrate the device on the tip of the grasper of the endoscopic surgical instrument.
Microfabricated silicon filters with a nominal pore size of 20 nm have been successfully fabricated and characterized. The filter consists of a filtration membrane on top of a silicon surface and a mechanical support on the silicon substrate. Two polysilicon layers together with a low temperature oxide layer are used to generate the filtration membrane on the front side of silicon wafers. The filtration function is accomplished by the flow channel generated from a sandwiched thin silicon dioxide layer. The thickness of the sandwiched oxide determines the particle size that can pass through the filter. Both distilled water and cell culture medium have been used to test the flow rate for this nanofilter. We have found that the flow rate of the nanofilter is highest at the beginning of the test, and then slowly decreases to its asymptotic values for both water and the cell culture medium. The observed flow rate is linearly proportional to the applied pressure in the ranges tested. The typical flow rate of distilled water for 20 nm filter with 1.19 cm2 effective filtration area is about 0.07 ml/min for applied pressure of 8 PSI. The filter successfully sustained pressure of up to 20 PSI.
We have newly developed a miniature optical scanning sensor capable of 3D recognition for pipe-inspection. The sensor, the size of (phi) 23 - 18 mm, consists of a miniature 2D optical scanner integrated with photo detector and piezoresistor a laser diode with collimating lens and an amplifier circuit. The 2D optical scanner actuated by piezoelectric actuator was applied to the sensor for miniaturization of the scanning mechanism. In order to detect on surface in pipe 3D, circular scanning pattern with variable scanning range, such as spiral pattern, was adopted. Reflected beam intensity from surface in pipe at each scanning position is detected by the photo detector. When scratches or obstructions exist on surface in pipe, the detected signal is changed. Shape recognition of the surface in pipe can be realized by detecting the change signals and its each scanning position information. In the case, piezoresistor fabricated on the torsional spring of the scanner was applied for detection of scanning position. Sensing range of 100 to 200 mm and resolution of less than 1 mm was obtained in 1 inch diameter pipe. This sensor could be useful for recognition sensors of miniature mobile robot in many inspection fields.
This paper deals with the structural proposal of the micro autonomous robotic system, and shows the design of the prototype. We aim at developing the micro robot, which autonomously acts based on its detection, in order to propose a solution to constitute the micro autonomous robotic system. However, as miniaturizing the size, the number of the sensors gets restricted and the information from them becomes lack. Lack of the information makes it difficult to realize an intelligence of quality. Because of that, the micro robotic system needs to develop the simple algorithm. In this paper, we propose the simply logical algorithms to control the actuator, and show the performance of the micro robot controlled by them, and design the Micro Line Trace Robot, which dimension is about 1 cm cube and which moves along the black line on the white-colored ground, and the programmable micro autonomous robot, which dimension is about 2 cm cube and which performs according to the program optionally.
In recent years, many new designs of micro robots have been developed. Miniaturization is a challenge and most mechanisms designed up to now are not autonomous, i.e. they don't have their intelligence and/or power supply on board. A new fully autonomous miniature mobile robot has been designed in our lab in a final year project. It has been programmed to follow a black line printed on the ground. An autonomous mechatronic system consists at least of a sensor, an actuator, a microprocessor to provide intelligence and a power supply. In our case, the robot's intelligence is based on a PIC16C71 microcontroller that controls its movement. To follow a black line, an infrared emitter and two receivers are placed at the front of the robot. As actuators, two watch motors are used. The gears of the watch's second hand are directly used as wheels to move the system. Two small batteries supply the energy to the motors and the microprocessor as well. The technical details of the mini mobile robot are as follows: dimensions: 20 mm * 8 mm * 15 mm; velocity: 40 mm/s; power consumption: 6 mW. This low power consumption allows the system to move autonomous for about 8 - 10 hours.
The aim of our project is to control the position in 3D-space of a micro robot with sub micron accuracy and manipulate Microsystems aided by a real time 3D computer graphics (virtual reality). As Microsystems and micro structures become smaller, it is necessary to build a micro robot ((mu) -robot) capable of manipulating these systems and structures with a precision of 1 micrometers or even higher. These movements have to be controlled and guided. The first part of our project was to develop a real time 3D computer graphics (virtual reality) environment man-machine interface to guide the newly developed robot similar to the environment we built in a macroscopic robotics. Secondly we want to evaluate measurement techniques to verify its position in the region of interest (workspace). A new type of microrobot has been developed for our purposed. Its simple and compact design is believed to be of promise in the microrobotics field. Stepping motion allows speed up to 4 mm/s. Resolution smaller than 10 nm is achievable. We also focus on the vision system and on the virtual reality interface of the complex system. Basically the user interacts with the virtual 3D microscope and sees the (mu) -robot as if he is looking through a real microscope. He is able to simulate the assembly of the missing parts, e.g. parts of the micrometer, beforehand in order to verify the assembly manipulation steps such assembly of the missing parts, e.g. parts of a micromotor, beforehand in order to verify the assembly manipulation steps such as measuring, moving the table to the right position or performing the manipulation. Micro manipulation is form of a teleoperation is then performed by the robot-unit and the position is controlled by vision. First results have shown, that a guided manipulations with submicronics absolute accuracy can be achieved. Key idea of this approach is to use the intuitiveness of immersed vision to perform robotics tasks in an environment where human has only access using high performing measurement and visualization systems. Using also the virtual scene exactly reconstructed from the CAD-CAM-databases of the real environment being considered as the a priori knowledge, human observations and computer-vision based techniques the robustness and speed of such a simulation can be improved tremendously.
This paper presents a high-voltage generator circuit as power supply for an electrostatic micromotor with process integration based on a standard 2 micrometers CMOS technology. This voltage multiplier circuit utilizes n-type with in a standard 2 micrometers CMOS process as a vital innovation to achieve electrically isolated and floated diodes. This design secures a high- voltage output limited only by the breakdown voltage of n-well to p-substrate pn junctions. For the purpose we used, the power supply can provide approximately 50 V dc output by inputting 5 V dc power and two non-overlapping 0/5 V clock signals. The demonstrated design has application in microbiotic and microactuated systems.
A series of millimeter-sized, addressable linear and rotary surface-driven electrostatic positioners are currently being designed and fabricated. The major components of these positioners are a thin copper-coated glass epoxy stator board and a carbon-coated polymer film slider which is placed on top of the stator board. Using modified Printed Circuit Board technique, a group of conductive electrodes are linearly or radially arranged on the stator board. On application of an excitation voltage pattern to the stator electrodes, a mirror image of the stator electrical charges will be induced on the film slider. Sequential switching of the voltage pattern will lead to electrical charge interactions, resulting in continuous motion of the film slider. Compared to the electromagnetic counterparts, these electrostatics-based positioners do not require the conventional mechanical assembly of transmission gears and rails for operation, thus are compact in design and light in weight. The potential advantage of low manufacturing cost may help this new type of positioners find a wide range of industrial, military, and commercial applications.
A tilting mechanism using piezoelectric actuators which has two rotation degrees of freedom has been developed. The dimensions of the body of the tilting mechanism are 10 mm in diameter and 24 mm in length. We have achieved the following specifications of the tilting mechanism; +/- 20 degree(s) rotational angle in the orthogonal two axes, 30 seconds of the angular resolution, 10 degree(s)/sec of the maximum rotation speed, and 1.75 Nmm of the maximum torque. This paper describes the structure and the experimental results of the linear actuator and the tilting mechanism.
In micro or nanorobotics, high precision movement in two or more degrees of freedom is one of the main problems. Firstly, the positional precision has to be increased (< 10 nm) as the object sizes decrease. On the other hand, the workspace has to have macroscopic dimensions (1 cm3) to give high maneuverability to the system and to allow suitable handling at the micro/macro-world interface. As basic driving mechanisms for the ETHZ Nanorobot Project, two new piezoelectric devices have been developed. `Abalone' is a 3-dof system that relies on the impact drive principle. The 38 mm X 33 mm X 9 mm slider can be moved to each position and orientation in a horizontal plane within a theoretically infinite workspace. In the stepping mode it achieves a speed of 1 mm/s in translation and 7 deg/s in rotation. Within the actuator's local range of 6 micrometers fine positioning is possible with a resolution better than 10 nm. `NanoCrab' is a bearingless rotational micromotor relying on the stick-slip effect. This 10 mm X 7 mm X 7 mm motor has the advantage of a relatively high torque at low rotational speed and an excellent runout. While the maximum velocity is 60 rpm, it reaches its highest torque of 0.3 mNm at 2 rpm. Another benefit is the powerless holding torque of 0.9 mNm. With a typical step of 0.1 mrad and a local resolution 3 orders of magnitude better than the step angle, NanoCrab can be very precisely adjusted. Design and measurements of the characteristics of these two mechanisms will be presented and compared with the theoretical analysis of inertial drives presented in a companion paper. Finally their integration into the Nanorobot system will be discussed.
The need for high precision robots dedicated to the assembly of microsystems has led to the design of new kinds of actuators able to reach very high positional accuracy over large distances. Among these, inertial sliders have received considerably interest in the last years. They have the advantage of being based on a simple principle that leads to a simple mechanical design. However, because they are based on the nonlinearity of friction, it is not easy to predict their stepsize repeatability. In order to understand the most important parameters affecting the precision of inertial drives, a theoretical study of a 1 degree of freedom inertial slider has been established. Analytical formulas describing the influence of different parameters, such as static and dynamic friction and mass distribution, have been developed. The effect of applied functions (sawtooth and parabolic), have also been studied. The theoretical cut off frequency has been found for each of the different waveforms, allowing us to predict the maximal and minimal working frequencies for the system. Thus, for each curve form, the repeatability of inertial sliders can be evaluated taking into account the uncertainties in the friction coefficients. The best suited waveforms for given constraints can therefore be selected. Simulations carried out from this have been successfully compared to experimental results.
Spherical motor, in principle, can make 3D rotation, with the advantages of small volume, less transmission chains and flexibly-controlled so as to be used for the drive in robot joints. This paper establishes a mechanics model of 3D drive of spherical motor with Lagrangian energy method. The result displays that there are serious nonlinear coupling torques among the shafts when the motor make 3D rotation. It further studies the method that rebuilds equivalent coupling torques with the help of spatial state detector, and decoupling control tactics to realize robot's 3D drive by means of feed forward, etc. It also gives a tactics of decoupling control in order to real-time implement this theory, and computer-aided numerical results of the entirely decoupling control, simplified decoupling control and undecoupling control are presented and compared. The results of simulation and sample machine's experiments are given to present this mathematics model and the decoupling control tactics are available and feasible.
In studying the properties of the attractor of an Iterated Function System, similarities were noted between bacterial chemotaxis and the asymptotic properties of a Random Iteration Algorithm (RIA). We have previously demonstrated global optimization by a swarm of agents using an RIA-like action selection rule, the Random Selection Rule. This capability suggests a least action approach to the specification of collective behaviors. In this paper we present simulations of a simple example of such a behavior--an emergent Braitenberg Vehicle whose frame, propulsion, control and sensing are all emergent properties, evolving from the behavior of simple `chemotactic' agents.
An initial concept is presented for a set of communications and command-control capabilities that can facilitate the development process for a system consisting of an arbitrarily large number of relatively simple (and probably small and inexpensive, although not necessarily `micro') robots--mechanisms to allow the human developer to quickly and easily see into the internal state of large numbers of robots, and to quickly and easily make changes to the robots' behaviors. The interface between the control station and the developer must be carefully designed in order to provide a serviceable development environment, and this environment, or subsets of it, should then evolve into the operator's station for deployed systems that require active control and monitoring. The development environment must provide the developer with a precise model for (re-) programming the elements of the system, while the system operator will require only the simplest functional model of the system as a whole that can support mission needs, combined with a convenient way to tell the system what to do.