In this study, a non-linear seven degrees of freedom vehicle model is used in order to design and check the performance of sliding mode controlled active suspensions. Force actuators are mounted as parallel to the four suspensions and a non-chattering control is realized. Sliding mode control is preferred because of its robust character since any change in vehicle parameters should not affect the performance of the active suspensions. Improvement in ride comfort is aimed by decreasing the amplitudes of motions and acceleration of vehicle body. Body bounce, pitch and yaw motions of the vehicle are simulated both in time domain in case of travelling on a limited ramp type of road profile. The robustness of the controller has been proved by using different vehicle parameters such as vehicle mass and damper ratios. Also, phase plane plots of them are plotted. Simulation results are compared with the ones of passive suspensions.

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This paper presents an adaptive control approach to a general multi-degrees-offreedom suspension model. A half car model, which involves bounce and pitch degrees of freedom for sprung mass and bounce degree of freedom for the unsprung mass is considered. The control concept diverts from the widely applied optimal control to adaptive control. The basic idea involves obtaining optimal performance of any nonlinear time varying suspension model by adaptively following a predefined reference model. The controller is designed for the first time to compensate for Squat and Nose-diving in the pitch mode of the vehicle during acceleration and deceleration maneuvers respectively. Discrete Model reference Adaptive Control (DMRAC) with parameter estimation is used to derive adaptation laws for the controller. The proposed control scheme is found to be computationally fast and does not require a priori knowledge of complex and nonlinear dynamic model and time varying parameters of the model. Simulation results for half-car model with all nonlinear suspension components subjected to deterministic input are presented. The results indicate good performance of adaptive controller even for large parametric variations in the model due to critical acceleration and deceleration maneuvers.

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For fast loading/unloading of the containers from a container ship, the quick suppression of the residual sway of the container at the end of trolley traveling is crucial. Due to the unmodeled dynamics of the plant and to disturbances like wind, a residual sway always exists. In this paper, a two-stage control for container cranes is investigated. The first stage control is a modified time-optimal control with feedback for the purpose of fast trolley traveling. The second stage control is a nonlinear control for the quick suppression of the residual sway while lowering the container at the target trolley position. The secondary control combines the partial feedback linearization to account for the unknown nonlinearities as much as possible and the variable structure control to account for the unmodeled dynamics and disturbances. The nonlinear control is investigated from the perspective of controlling an underactuated mechanical system. Simulations and experimental results are provided.

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We present experimental results on the vibrational characteristics of the automotive sub-system comprising the human body, seat, steering wheel and pedals. The magnitude of the vibrations transferred to a driver from the seat, steering wheel and pedals have been measured with both sinusoidal and random excitations in the vertical direction at frequencies up to 20 Hz. Measurement points were located on the surface of the head, chest, hip, thigh, shin, upper arm and lower arm. Eleven subjects were used to investigate the effect of some variable factors, such as arm angle, that may affect human dynamic behavior. It was found that arm angle in driving posture has a substantial influence on the dynamic behavior of the human body while driving. Some results are presented in the form of parametric graphs and tables. The results are useful for improving ride comfort, maneuverability, arid safety.

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Sliding Mode Control (SMC) as a Variable Structure System (VSS) and a nonlinear control theory, has been widely used in various engineering fields, and carried out excellent performances in practical use. The purpose of this study is to attempt to utilize SMC for hot strip hishing mill and present the details of design procedure of discrete time sliding mode servo-controller. The plant is described as a MIMO system and the thickness measuring dead-time is added into state space equation as a series of delay elements. The influence of this dead-time can be nullified by the use of an augmented VSS observer. A state predictor is also used to compensate for the time delay caused in calculation and transmission of process control computers. A new approach of discrete sliding mode control which can remove the chattering phenomenon entirely, is proposed with the use of linear reaching law. The usefulness and robustness of the SMC are demonstrated through computer simulations under plant perturbation and external disturbances, and compared with a conventional optimal servo-controller.

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The digital servo system of a magnetic disk drive has to overcome poor seek control performance caused by the mechanical gain variations and force disturbance variations in each head. This paper presents an adaptive seek control strategy which adjusts the acceleration feedforward gain to minimize the square of the velocity error. The adaptive seek control is implemented using a digital signal processor and its control performance is good.

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In this paper, global exponential stability for a class of interval time-delay systems is investigated. Delay-independent and delay-dependent criteria are proposed to guarantee global exponential stability of the interval time-delay system. The guaranteed convergence rates of systems are obtained by finding the unique positive solution of some equations. Some comparisons are made to show that our results are less conservative than some results in recent literature.

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The automobile industry in Japan is moving towards high-per formance and highquality engines, which are high-powered and compact. In Europe and America, this goal has already been achieved and multicylinder high-powered engines have been developed. The maximum number of cylinders in an engine for a motorcar in these countries is 16 cylinders in a V-type and this engine is used in sports and racing cars. The next largest engine size below the 16 cylinders is the V-type 12-cylinder engine which is widely used in many luxury vehicles. In Japan, however, although the V-type 12-cylinder engine is the largest, it is loaded only into one type of car. In this paper, we analyze the exciting moment of the V-type 14-cylinder engine which is positioned between the V-type 16-cylinder and 12-cylinder engines, but does not yet have a practical use as a motorcar engine. Here, we consider the characteristics and evaluate the V-type 14-cylinder engine for use in a motorcar.

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This paper describes the dynamic characteristics and precision rotational positioning of the mechanism with a harmonic speed reducer. The harmonic speed reducer is the reduction gear that is often used for precision robots because they can be made very compact and lightweight without backlash. However they have the friction and the low stiffness which make the positioning performance low. The purpose of this research is to clarify the suitable control method for the rotational positioning mechanism with the reduction gear and to realize high speed and high precision rotational positioning over a wide range. For this purpose, first, the characteristics of the mechanism are examined experimentally. The experimental results show that the mechanism can be represented by two kinds of models, those are micro and macro dynamic models. Then, by using the controller including a disturbance observer, the mechanism has the positioning accuracy better than 1" on the working range more than 4.0×10⁵"

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This paper deals with simultaneous optimal design of structure and control systems. For structures with collocated sensors and actuators, a stabilizing statefeedback gain and an estimator gain can be obtained easily. Using these two gain matrices, we can parameterize all stabilizirlg controllers for the structure by Youla parameterization scheme. Since stability of the closed-loop system is guaranteed, we can optimmize design parameters in the structure and the controller simultaneously without taking two-step design procedures which consist of the step for controller synthesis and that for structural parameter tuning. Hence, convergence to the local optima is achieved with standard descent-based nonlinear optimization techniques (steepest descent, Newton method, etc. ). By a design example, we show the effectiveness of proposed design method.

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A new identification method for acoustic impedance of an acoustic duct system is developed in this study such that a proper working model for active noise control can be acquired. A bite-length acoustic duct system with an exciting input at one end and a partially reflective boundary condition represented by its acoustic impedance at the other end is considered. Two microphones placed at two different locations in the kite-length duct are used to obtain measured frequency responses. A simple genetic algorithm in corporation with an acoustic model is then utilized to identify the acoustic impedance from the measured frequency responses. Advantage of this proposed identification method is that the two microphones can be arbitrarily mounted. Both computer simulation and experimental results demonstrate the effectiveness and feasibility of the proposed identification method.

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The nonlinear response of a one-dimensional oscillator with two-sided amplitude constraints or with a single-sided amplitude constraint which is preloaded against a stop and subjected to nonharmonic excitation is investigated. Positive clearance and preload systems are discussed. The amplitude and stability of the periodic responses are determined and a bifurcation analysis of these motions is carried out. Perioddoubling bifurcations and degenerate impacts occur in our model. Some parametric regions are shown to possess chaotic motions. The stable linear motion can coexist with stable nonlinear motion or transient chaos. It is found that the degenerate impact can cause a sudden change in the response structure not only to a stable motion but also to chaos.

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In this article, a new and efficient multilayer neural networks learning algorithm is presented. The key concept of this new algorithm is the two-stage implementation of the steepest descendant method. At the first stage, the steepest descendant method is used to search the optimal learning constant η and momentum term a for each weights updating process. At the second stage, the Delta learning rule is then employed to modify the connecting Weights in terms of the optimal η and α. Computer simulations show that the proposed new algorithm outmatches other learning algorithms both in converging speed and success rate. On real industrial application, we first apply the new neural network learning algorithm to the identification of a highly nonlinear injection molding barrel system. Experimental results demonstrate that the new algorithm can precisely identify the complicate injection molding barrel system. Further more, a self-tuning PID controller for precise temperature control based on the trained neural network barrel model is developed. Real experiments show that the self-tuning PID controller can precisely control the barrel temperature within ±0.5°C.

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The stability test method for the observer-based time-delay control system is discussed. Because there are uncertain parameters and time-delay terms in the control system, the frequency response plot based graphical method is extended and adopted to analysis the stability of the closed-loop system. The stability of the synchronous control of a four-cylinder electrohydraulic servosystem studied in Part I is verified to be stable by using the proposed method.

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This research is concerned with the fault diagnosis for machines using neural networks. Generally, it is difficult to diagnose machine's fault by the conventional technique. In this research, two new fault diagnosis systems are proposed which one diagnoses a fault based on behavior of the object system, and another diagnoses a fault based on power spectrum of the object system. In the former, when an object system is a normal state, the system identification is performed by the neural networks. The diagnosis system detects a fault by finding the behavior's gap between the state of the real system and the identified normal one, and also the fault part is specified by fault diagnosis neural network. In the latter, neural network learns power spectrum of both the normal and fault states for the object. When a fault occurs, fault part is diagrnosed by fault diagnosis neural network based on power spectrum. Finally, through simulation and experiment, the effectiveness of proposed fault diagnosis systems is verified.

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The high operating speeds of a linkage result in the shaking force/moment and the driving torque to change significantly. The balancing effects by the mass redistribution method or the counterweight method are not satisfactory sometimes. In this paper, we propose a new mixed mass redistribution method. The optimum dynamic design using the new method is investigated, based on genetic algorithms. The results of the counterweight method, the mass redistribution method and the new method are compared, and it is shown that the new method can reduce the shaking force/moment and the driving torque more effectively than the methods used previously. Moreover, it is also demonstrated that using genetic algorithms we can obtain optimum dynamic characteristics more efficiently than by the traditional nonlinear optimization techniques. The small element method is used to obtain the shape of links according to optimized linkage design parameters.

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This study develops a flexible artificial hand system with slip sensors. The artificial hand is composed of four flexible actuators. Two pairs of two opposite actuators are driven by the independent air pressure sources each. In each pair, one of opposite pair of actuators is equipped with a slip sensor. The slip sensor is composed of a photo reflector and a conductive rubber sensitive to load force. The contact of the hand to an object is detected by the change of resistance of the conductive rubber. After the detection of contact, the slip velocity is measured by calculating the cross-correlation function of the output voltage wave forms of two photo transistors in the photo reflector. The grasping force of the hand is increased according to the measured slip velocity. The calculation of the cross-correlation function and the generation of control signals are made in a host personal computer. From the experimental results of holding several objects, the hand system is proved to grasp suitably the object whose weight is previously unknown.

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In general, there is no good hardware of tactile display for tele-robot and virtual reality, because to present the curvature of the curved surface with continuous values is too difficult. On the other hand, in the psychophysical studies, human visual arid tactile sensations have illusory fusion characteristics. Namely, the human sensory quantity on size, position and orientation of object is different from the real quantity. Therefore, we can recognize curved surface of real objects through visual and tactile sensations, even if exact tactile information is not presented. Furthermore the visual information is realize easily by computer graphical technology. So, by utilizing human characteristics of sensory illusory fusion, realization of the tactile display can be simplified. In this study, human characteristics of visual and tactile sensory fusion are measured by psychological experiments, arid a tactile display is designed based on the results of the experiments. In the designed tactile display, only some curved patterns are utilized of instead of presenting many curved surface patterns. Namely, using the human sensory fusion characteristics on visual and tactile sensory fusion, the tactile display carl be simplified.

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A simple strategy for carrying a large object with the cooperation of multiple position-controlled robots is proposed. In cooperative systems handling single objects, compliance is necessary for each robot to avoid excessive inner forces caused by mutual positioning errors. However, since the majority of commercial industrial robots have PID position controllers, the necessary compliance cannot be achieved by servo systems. Thus, mechanisms consisting of passive joints are installed in a cooperative System as mechanical compliance. First, the mechanical compliance required for the cooperation of position-controlled robots is derived. From the theoretical results, it is determined that the maximum number of robots that can directly support a single object is six. Second, the statics and error characteristics of cooperative systems including compliant mechanisms are analyzed. An example of the cooperation of three mobile robots is designed using passive joint mechanisms. Finally, the strategy is extended to cooperation among an arbitrary number of mobile robots by building hierarchical structures with passive joints.

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This paper presents preliminary experiments on automatic programming of motions of a humanoid robot by human demonstrations. Aiming to develop the "teaching by human demonstrations" system, three preliminary experiments are performed: (a) oN-line recognition of human postures, (b) on-line imitation of human postures, and (c) recognition of the pick and place task and generation of a motion of a robot arm to play it back. The humanoid robot having its head with stereo camera arrangement, a 2-DOF neck and dual 7-DOF arms, is used in these experiments. The experimental results prove the potential of an easy and natural teaching by human demonstrations.

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We have previously developed a navigation system for autonomous mobile robots. It can find landmarks on the ceiling to move and work. However it is impossible to recognize landmark in case that the size of landmark is different from the size of template. In such cases, the robot cannot continue to work. Therefor we proposed Variable Template Matching (VTM) which makes it possible to recognize landmarks of different sizes. We realize VTM by using the optimization method that is called Evolution Strategy (ES). The robot can recognize the landmark faster by binary density projection to infer landmark parameters. Minus Fuzzy Template is useful for the robot to avoid misidentifying.

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We present a method of route selection for a vision guided mobile robot with art odometry system, given an uncertain map. The robot first generates candidates of the routes, which are expanded to possible loci in consideration of the map uncertainty. It then makes an observation and movement plan along each locus and computes the minimum traveling time. Uncertainties of movement and visual sensing are considered in this step. Finally, for each candidate route, the robot computes its expected traveling time from probabilities of loci It selects the route with the least expected traveling time as the optimal route. The advantage of the planning method is that the observation and movement planning are incorporated in path planning to obtain the optimal plan. The three sources of uncertainty are considered in a unified manner in our method. The method has been implemented and tested to validate our claim.

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This paper proposes a simulator that can depict the rotational vibration of a spur gear having any types of tooth surface deviation including both tooth profile deviations and tooth helix deviations. The developed simulator is based on a single degree-of-freedom model consisted of equivalent mass, damping and mesh stiffness of a gear pair. The mesh stiffness is calculated by considering the effect of the tooth helix deviation which brings non-uniform load distribution along the contact line of the tooth pair. The dynamic load tests have been performed to verify the simulator changing both helix slope deviations of the driven gear and torque. The analytical result under each operating condition is in good agreement with the experimental result. Moreover, the damping ratio of the test gear system is evaluated as 0.03 with the measured vibration responses, which is less than conventional expectation value of 0.07.

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The fatigue strength of carburized gears is influenced by the latent defect in the surface layer. To clarify this influence, the bending fatigue strength of carburized gears with an artificial notch is evaluated in this paper. The notches are processed by wire-cut electrical discharge machining (WEDM) and focused ion beam (FIB) etching to obtain the required depth. The fatigue strength of the tooth with the notch over 35 pm in depth decreases markedly in comparison with the nonnotched tooth. In the case where the notch is shallower than 20 μm, cracks initiated from the notch are not observed and the strength is not reduced. By assuming a crack of the same length as the notch, the stress intensity factor K_I is calculated considering the effect of residual stress. The strength expected from the stress intensity factor range is higher than the obtained strength of the gear with the notch.

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The monitoring and diagnostics of the bearing have been received considerable attention for many years because the majority of problems in rotating machines are caused by faulty bearings. The malfunction of rotating machinery in plants due to some defects may cause shutdown of the plants, resulting in high maintenance cost. Overly generalized predictions are problematic due to concept classification. In particular, the boundaries among classes are not always clearly defined. To avoid such problems, the idea of fuzzy classification was proposed. In this paper, in order to automatize the diagnosis of a rolling element bearing using the fuzzy classification along with their construction algorithm, the fuzzy dichotomy techique as an acquisition of structured knowledge from held case history data is used for validating the diagnosis capability.

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When a path of contact and its contact normals of a gear pair which has symmetrical convex tooth surfaces (elastic) modified slightly from true involute helicoids for one member and the conjugate surfaces (rigid) of the true involute helicoids for the other are given under load as functions of angle of rotation, the equations of motion are solved to obtain the dynamic incremental load algebraically. The equations of motion of all kinds of gear pairs having modified involute helicoids like mentioned above are expressed by the same ones which have been already obtained for the involute helical gears with the modified tooth surfaces. So that the solution, namely the dynamic incremental load is also expressed the same from cylindrical to hypoid gears. The variation of bearing loads is calculated, which consists of both the dynamic incremental load and the fluctuation of the static load that is generated by the wrong selection of the path of contact in the small contact ratio.

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In interferometric measurement, it is important to obtain a clear interference fringe pattern. A high density of fringes in interferometric measurements of involute gear tooth induces noises in the measuring signal and makes analysis difficult. In this paper, we propose a new optical system to obtain an interference fringe pattern of low density. A spherical concave lens is added in the optical path of the reference beam to deform the curved figure of phase of the reference beam over a charge-coupled device image sensor. By selecting a suitable focal length of the inserted concave lens, the phase difference between the reference beam and the object beam becomes fairly small over the CCD image sensor and the fringe density of the interference fringe pattern decreases. The effect of this new optical system is investigated.

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In this study, we investigated the influence of secondary factors, i.e., the slip velocity, gas leakage from the edges of porous surface, thickness of restricted layer and the effective area of porous surface on the characteristics of an externally pressurized porous annular thrust gas bearing which has a thin restricted surface layer. By comparing numerically calculated results with experimental ones, it was found that the numerically calculated results which take account of secondary factors agree well with the experimental results in a clearance region greater than 2 μm.

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The opposed dies shearing process is one of the precision shearing processes based on the idea of smooth surface formation by cutting mechanism and can be applied to brittle materials. This feature is considered to be available for finishing of cast products and a new demand for this process is expected. In this paper, precision shearing of cast materials by the opposed dies shearing process was studied. Four kinds of cast iron and cast aluminum under practical use were tested and unique characteristics in shearing brittle materials were cleared. Influences of working conditions on the quality of sheared edge were investigated and optimum conditions were given for each material. In comparison with other shearing processes, it was conned that the sheared edge quality by this process was much better than that by conventional shearing process and almost equal to that by shaving process.

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Concurrent Engineering is a methodology that allows designers and manufacturing engineers to work in parallel, or concurrently, during various stages of product design and manufacturing. This paper proposes a concurrent design method for mechanical systems that utilizes operator-acting modules. In this method, in order to simplify the system being considered, it is first divided into modules, and then the modules' specifications are changed via operators, which act to expand the design space. By using simple modules to express the mechanical system, several stages of design and the attendant manufacturing variables can be treated within the modules concurrently and in parallel, so that high performance and high quality machine products can be realized in a short time. The proposed method is applied to the design of a material handling manipulator consisting of several links, and the validity of this design method is discussed.

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This paper presents a new working method of controllable Electro-Chemical Honing (ECH) of gears as follows. A gear shaped cathode which is meshing with a workpiece gear during machining is exposed as cathode pole only on a strip on the tooth dank. By varying the center distance between the cathode and the gear slowly, the electrolysis zone sweeps over the tooth flank from root to tip (slow scanning as we call it). Since the center distance is varied by a step motor, so the time of dwelling of the pole, and hence the amount of metal removal on different spots of the profile can be controlled by programming. An on-line profile error measuring device is provided. The computer calculates the required discharging time which has a relationship with dwelling time, and sends out the programming to control the metal. removing rate so as to cancel the error or to produce profile correction needed by silent transmission. A mathematical model is built for calculating the required discharging time. Several ground gears with typical profile errors are subjected to trial machining on this working principle. It cancels the profile errors very efficiently. The experiment demonstrates that the machining method can step up the profile accuracy to very high order on the basis of the general accuracy guaranteed by the proceeding operationgear grinding.

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A PC-based virtual machining simulator has been developed to evaluate the machining operation performed by the NC program in the process planning stage. The virtual machining simulator consists of an NC program simulator, a geometric simulator and a physical simulator. The NC program simulator can calculate the CL (Cutter Location) data and operational time and detect cutting conditions such as feed rate and spindle speed by interpreting the NC program. The geometric simulator demonstrates the machining process and detects implicit cutthg conditions such as depths of cut and metal removal rate. The physical simulator estimates the instantaneous cutting force and machining error based on the cutting models. Process planners easily recognize the problem in NC programs and evaluate machining accuracy before the real machining operation using these estimated results. It is easy to understand the differences in the operational time, cutting force and machining accuracy of two NC programs based on their case studies.

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