Skilled human operators can adjust various conditions of manufacturing system and deal with unexpected troubles flexibly and appropriately. However, the operators can possibly fail the adjustment and dealing at times, because of fatigue, carelessness, bad physical condition, etc. The failure may cause some serious delay of the manufacturing processes and even physical danger to the operators. So, an intelligent system for avoiding the failure or warning its signs is desired to improve their working environment. To develop the system, a reliable recognition technique of operator's motion is indispensable. In this research, the recognition system of five kinds of motion in cylindrical grinding machine operation has been investigated by utilizing a small gyro/acceleration sensor and DP matching method. The similarity between the reference motion (standard pattern) and an input motion has been evaluated by the index of DP matching, or the pattern distance. The reference motions have been derived by averaging several typical motion data after time normalization. As the result, to recognize the objective five motions, first, the similarity indices by only angle data should be compared each other. Then, the similarity indices by only acceleration data should be compared, if necessary.
This study focuses on the construction of an information processing and control system using an actual cell. The emphasis is placed on both the initial location of a cell and the cellular distribution density when a nerve cell is cultivated. On the basis of physiological knowledge, a calculation program was made which simulated the activity of a nerve cell. Then, the excitation transmission from a cell was observed in the simulation by randomly changing the initial cell location. The transmission performance of the excitation was evaluated by using the transmission ability function defined in this study. It is found from simulation results that a nerve circuit network forms a closed circuit when the distribution density of a cell becomes large, although it is a barrier in transmitting the excitation. Further, the cellular distribution density shows its optimal value when a cell condition is adequately arranged. As a result, there is the possibility of controlling the performance of a nerve circuit network by changing the initial cell location.
The application of dynamic system in the living organism is very instructive. The swimming of micro-organism, sea urchin spermatozoa, by flagellar propulsion is employed for the simulation study to discuss the control parameters for propulsion. The model consists of the arc units connected in series and each unit was approximated by multilink system. The movement of the model by flagellar propulsion was simulated based on the force coefficient introduced by Gray and Hancock. The movement of the model was determined by the function of curvature of each arc unit. Simulated velocity and efficiency of straight swimming were similar to the results of previous studies. The change of propulsion direction was simulated. The control parameters of curvature of arc unit which were proportional to the curvature of the track of swimming were obtained. The velocity and efficiency along the tracks had little difference with various radies of curvature of the tracks.
The purpose of this study was to develop a robot arm with human arm characteristics. For development of a robot arm that works with man, the robot arm must have characteristics of the human arm. The biceps brachii and triceps brachii of the upper limb were studied. Major characteristics of muscles are elastic factor and damping factor. In order to explore these characteristics of muscles, a human arm experiment was conducted. Using the characteristics obtained from the experiment, a robot arm was manufactured. The size of the robot arm was the same as that of the arm. An electromagnetic actuator system, which was developed to realize characteristics of human muscles, was employed. The actuator has a bobbin with some coils and the moving part that consists of a rare earth metal permanent magnet. The moving part of this actuator is driven by repulsive force in the magnetic field, which is generated by exciting each coil and the magnetism of the moving part. The excitation current is supplied to coils by the driver circuits, which is controlled by a personal computer. It was confirmed that the robot arm has the human arm characteristics.
It is estimated that twenty five percent people of Japanese population will be more than sixty five years old in 2020. Under the present conditions, development of a welfare machine is desired to assist the phisically handycapped person and old people. The machine which are developed at present are big system, or it is difficult to manipulate them. The purpose of this study is to develop compact, light weight, multi functions, easy manipulation and human friendly welfare machine. This system consists of lift and transfer part. It was developed lift part using two 3-DOF (degree-of-freedom) parallel robot which are driven by pneumatic actuators. In this paper, it was proved by these experimental results (position control, force control, cooperative control) that this system has good potential.
The accuracy of ordinary magnetic bearings is not high enough because displacement sensors used for feed-back are inaccurate. The aim of the paper is to clarify limitations of the positioning accuracy of an object of an electromagnetic levitation system in which a flux density sensor and a current sensor are used for estimat-ing the displacement of the object. First, a displacement estimation method using flux density and current signals in an electromagnet is discussed. Then a non-contact positioning system controlled by electromag-nets, Hall elements and current sensors is introduced. The system is provisionally positioned with a precision displacement sensor. Comparison of the resolution, frequency characteristics and measurement range is made between the estimated displacement and the output of the precision sensor to evaluate the accuracy of the estimation. After that, the object is controlled using the estimated displacement as the feedback signal and the accuracy and stability of the estimated displacement are examined. The experimental results show that the resolutions of estimated displacement and positioning were 0.25 μm, the positioning range was more than ± 100 μm, and the stability of positioning due to the ambient temperature variation was 3.0 μm/°C.
As the machine tools are shifting to high precision cutting, it is necessary to develop an effective instrumentation system and to establish an evaluation method for the spindle run-out error. In this paper, a new measurement system for the run-out error was developed by utilizing an transmitted light beam method. Also a new evaluation method was established by separating the run-out error into rotational error and tool chucking error. The measuring principle is based upon edge detection technique in which a halved photo detector is used to quantify the amount of the transmitted light through the both sides of the pin-gauge used as a master specimen. By providing two similar optical setups which are placed perpendicular to the rotating axis of the pin-gauge, an X-Y displacement measurement system of the pin-gauge was built up. The run-out error of the spindle can be known directly by evaluating the displacement of the pin-gauge through its Lissajous figure. Finally, it was clarified that the performance of the developed evaluation system is practically acceptable.
his study proposes a new coordinate measuring machine (CMM) based on a parallel mechanism consisting of closed loop link mechanism. The use of this mechanism instead of conventional orthogonal slide mechanism will potentially improve the stiffness, accuracy and efficiency of the CMM. This report describes the fundamentals, type synthesis, number synthesis and kinematics of the new CMM. Synthesized parallel mechanism with spatial three degree-of-freedom (DOF) comprises one base, one stage and three sets of three types of joints which are a revolutionary joint, a spherical joint and actuated prismatic joint. The direct kinematics calculated the coordinate of the probe from the link length, and estimated the measuring space. An experimental manipulator with 3 DOF was constructed to examine the validity of the new mechanism.
This paper describes a miniature robot which has been developed for the flexible micro indentation. The basic mechanism of this small robot is the combination of piezo elements for microscopic locomotion and electromagnet for clamping on the working surface. This arrangement can give the precise mobility on any curved surface without special guideways. In order to provide micro manipulation, the small electromagnet actuator of voice coil motor with 2 control axes is mounted on it. This electromagnet actuator is also capable of locating the position of micro tool in lateral and indenting the tool on the sample. In the experiment, the performances such that the small robot can travel precisely and provide several micro dents of 2 μ m to 200 μm in diameter are presented. With the help of the CCD camera vision instrument and the computer assisted control system that can monitor the coordinate position of the small robot and govern its motion, it succeeds in moving to the specified working area automatically and providing small Japanese characters which are composed of microscopic dents within 100 μm square.
This report deals with the way to decide tool posture, the way to analytically calculate tool path and the way to check the interference between tool system and work one. In the tool path calculation, basic equations are derived using the principle that the tangent slope at a cut point on a work and the one at a cutting point on a tool edge are identical. A tool posture decision procedure using the tangent slope at each cut point on a work is proposed for any shape of tool edge. A checking method for collision interference between a tool system (tool, tool holder, spindle head etc.) and a work system (work and its fixing equipment etc.) is also shown. The reliability and calculation efficiency of this algorithm is verified by test cutting of an impeller.
This paper describes the mechanical strength of the cobaltless sintered WC which is suitable for the substrate of diamond-coated tool. Cobaltless WC is sintered under different sintering conditions by Spark Sintering. Then, its mechanical characters are evaluated by Rockwell hardness on the A scale and the bending strength. As a result, by selecting the proper sintering condition, the particle size is 1.0-1.4 μm, sintering temperature is 1800-1900°C, sintering pressure is 50 MPa and sintering time is 600 s, the hardness of the cobaltless sintered WC is improved to 98 (HRA), and the bending strength is improved to 1.3 GPa.
The lapping of ceramic green balls are very difficult because of causing breakage or chipping easily in lapping process. This paper deals with the experimental result obtained by the lapping tool newly developed. This new tool, which is called the elastic contact lapping tool, provides the cutting edge which is covered the edge of ordinary tool with the nylon mesh clothe. In the lapping work of green ball by this, the stock removal in lapping is able to control by adjusting the height of tool edge stuck out of the nylon mesh clothe. Since the chip collected in the valley of tool is prevented to adhere the surface of ball with the nylon mesh clothe, it is able to obtain the high quality surface ball. The optimum lapping conditions in the new tool is found for the rapid improvement of green balls.
The influences of specific gravity, hardness, surface area and material of workpieces on finishing results are investigated in the dry centrifugal barrel finishing. The media used in experiment is triangular prism of nylon mixed with abrasive grains of aluminum oxide (#320). Its size is 4mm in each side and 4mm in height. The turret rotation speed is fixed at 240rpm and media charging ratio is varied from 20 to 50vol% of barrel capacity. The volume of workpieces is fixed throughout all the experiments. Materials of workpieces are steel, aluminum alloy, brass and titanium alloy. The edge radius increases with the specific gravity of workpiece while the surface roughness is almost independent of it. The relative stock removal, the edge radius and the surface roughness decrease with the increase of the hardness of workpiece. The relative stock removal increases with the surface area of workpiece while the surface roughness and the edge radius are almost fixed with the exception of the surface roughness at a smaller surface area and the edge radius at 20vol%. The influence of material of workpiece on finishing results is a combination of influences of its specific gravity and hardness.
It is very important to get fine surface roughness in the milling process for reducing the production time of plastic molds. However, few research works on the effect of cutting conditions to the surface roughness have been conducted in the fiveaxis controlled machining centers. In this paper, both of the radial and axial motions of the ball-end mill including the spindle axis of the machining center are considered in the computer simulation as well as the profile of cutting edge. In the experiments, actual milling has been also done changing the tilting angle of the spindle axis relative to the surface of the workpiece. The simulated results have a good agreement with the experimental ones, and the best surface roughness is obtained at around 5 degrees of the tilting angle. In addition, it is made clear that there are several patterns on the finished surface and those patterns are generated corresponding to the relationship between the angle position of cutting edge and the linear position of tool relative to the table position as well as the run-out of the tool.
This paper describes the mechanism of brittle-ductile transition of monocrystal silicon at a high temperature and its feasibility for ductile mode cutting. The micro-cutting tests were carried out at various temperatures, and for various cutting speeds and depth of cut by using a newly developed cutting device. The critical depth of cut is closely related to the material temperature and cutting speed. When the material temperature is 973K at a cutting speed of 1mm/s, the critical depth of cut is about two times that at room temperature. The critical depth of cut decreases with increasing in cutting speed. The specific cutting force is nearly constant at various temperatures. The residual stress on the ductile-mode cutting surface is compressive about 200MPa.