A vibration-type measurement system characterized by the use of an undamped dynamic vibration absorber has been developed. However, inevitable damping in the absorber may cause measurement error. A new method of measuring mass is proposed to overcome this problem. The measurement system utilizes the fixed point of a mass-spring system with a dynamic vibration absorber so that the mass is estimated regardless of damping in the absorber. A phase-looked loop (PLL) is used to achieve tuning. The principle of measurement is described on the basis of a mathematical model. A measuring apparatus was designed and fabricated, and several of its basic characteristics were studied experimentally. Damping of the primary system was found to affect fixed point formation. By reducing the damping of the primary system by a voice coil motor, the measurement conditions were achieved. The efficacy of the apparatus was studied both analytically and experimentally. The measurement conditions were realized automatically by the PLL. Mass measurement was performed while the PLL was operated; the average measurement error was within 0.21 [%].

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This study develops an active vibration control unit for flexible booms for crop spraying. The unit consists of a fly-wheel, servo-motor, gyro sensor, and micro computer, and is termed an Active Wheel Damper (AWD). The AWD can be simply mounted on any flexible boom structure and enables effective damping of vibrations. The study further combines an adaptive disturbance cancellation controller and a sky-hook controller to obtain better vibration suppression performance, and names this controller a Sky-hook with Adaptive Disturbance Cancellation control (SWADC). The effectiveness of the developed vibration suppression unit is demonstrated by experiments of suppression of horizontal vibrations, which are in a direction parallel to the traveling direction of a spraying vehicle, of a flexible boom mounted on the vehicle pulled by a tractor. In the experiments, the AWD increases in damping for the motion of the deflection angle, which is the slope of deflection curve, of the flexible boom to suppress the translational flexible vibrations of the boom.

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This paper presents a sliding mode controller of semi-active suspension systems. The sliding mode controller is designed by the describing function method so that a switching function is enforced into a desired limit cycle instead of a perfect sliding mode. Although the proposed sliding mode controller cannot generate the limit cycle as desired because of the passive constraint of controllable dampers, restricting the switching function in the vicinity of the origin can suppress the deterioration due to the passive constraint, such as increase of jerk of the sprung mass. Finally, simulation results show the effectiveness of the proposed controller.

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The design method of a robust adaptive trajectory tracking control strategy of nonholonomic wheeled mobile robots is discussed. The aim is to develop a dynamics control system, because kinematics control laws of mobile robots is well known. The resulting dynamics control strategy can compensate not only the physical parameters of mobile robot, but also the input torque uncertainty and the input torque disturbance based on adaptive H_∞ method. Numerical simulations are given to show the effectiveness of the proposed method.

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This paper deals with an approximate linearization control of 2-DOF underactuated-by-1 nonlinear systems, proposing a novel linearization coordinate which reduces the approximation error over the state space around the operating point. The coordinate is analytically constructed in a systematic way by solving two first order linear partial differential equations and the solution is given in an infinite series of configuration variables. The resulting linearization feedback is highly nonlinear and the basin of attraction of the stabilized system using proposed coordinate is large, comparing with those of a conventional first order or other lower order linearization coordinates. The approximate linearization control based on the proposed coordinate is applied to the stabilization of a rotational inverted pendulum; the advantage is verified in simulations and experiments. Some perspectives on availability of the linearization coordinate are discussed and they are computed also for a mobile inverted pendulum, Acrobot, and for Pendubot as examples.

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This paper presents development of a control system for ecological driving of an automobile. Prediction using traffic signal information is considered to improve the fuel economy. It is assumed that the automobile receives traffic signal information from Intelligent Transportation Systems (ITS). Model predictive control is used to calculate optimal vehicle control inputs using traffic signal information. The performance of the proposed method was analyzed through computer simulation results. It was observed that fuel economy was improved compared with driving of a typical human driving model.

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In this study, the objective is to build a wheeled mobile robot which can move independently avoiding obstacles. To move autonomously, this robot is enabled to detect obstacles' shapes and conduct self-localization. Also, this robot can move by tracking trajectories designed by the robot itself, based on the information about the obstacles' shapes and the robot's position and attitude angle. The optimal trajectories which lead the robot to its destination are designed by using a unique optimization method. As convergent calculation is performed by setting the variables within a certain range in this proposed optimization method, the optimal solutions can be obtained approximately, even in cases where there is a difference between the number of input and output variables, and when the nonlinearity is strong with restraint conditions. In this thesis, the effectiveness of the optimal track designing method used is proven and the method deemed as appropriate.

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Recently, R/C helicopter is used in fields of aerial photography and aerial investigation. But helicopter rotor blades are not covered, and the thrust is generated by high rotational speed. Thus R/C helicopter has a high risk of damage. In this study, we developed a new flying object using ducted fans instead of rotor blades. At first, PD control was employed for pitch and roll attitude control, but it caused steady state error. Moreover, PI-D control was used instead of PD control, and it reduced the steady state error. We succeeded to achieve stable hovering by 3-axes (roll, pitch and yaw axis) attitude control.

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This paper proposes a traction control system for an electric vehicle with GPS system to measure the vehicle-body speed. This control system is a nonlinear system, which is designed by following Lyapunov stability theorem. The main objective is to control the wheel slip when the vehicle accelerates on a slippery road condition. The effectiveness of this control system is verified by satisfactory experiment results.

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In this study, we construct an evaluation system for the muscular activity of the lower limbs when a human pedals an electric power-assisted bicycle. The evaluation system is composed of an electric power-assisted bicycle, a numerical simulator and a motion capture system. The electric power-assisted bicycle in this study has a pedal with an attached force sensor. The numerical simulator for pedaling motion is a musculoskeletal model of a human. The motion capture system measures the joint angles of the lower limb. We examine the influence of the electric power-assisted force on each muscle of the human trunk and legs. First, an experiment of pedaling motion is performed. Then, the musculoskeletal model is calculated by using the experimental data. We discuss the influence on each muscle by electric power-assist. It is found that the muscular activity is decreased by the electric power-assist bicycle, and the reduction of the muscular force required for pedaling motion was quantitatively shown for every muscle.

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Recently, engineering design environment of Japan is changing variously. Manufacturing companies are being challenged to design and bring out products that meet the diverse demands of customers and are competitive against those produced by rising countries⁽¹⁾. In order to keep and strengthen the competitiveness of Japanese companies, it is necessary to create new added values as well as conventional ones. It is well known that design at the early stages has a great influence on the final design solution. Therefore, design support tools for the upstream design is necessary for creating new added values. We have established a research society for 1D-CAE (1 Dimensional Computer Aided Engineering)⁽²⁾, which is a general term for idea, methodology and tools applicable for the upstream design support, and discuss the concept and definition of 1D-CAE. This paper reports our discussion about 1D-CAE.

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