Akihiko Yoneya

Two-valued PID controller

A discrete-time proportional integral derivative (PID) controller, the manipulated variable of which takes two values, i.e., ON and OFF, is proposed and analyzed. Oversampling technology is employed in the controller design. As to the structure of the controller, a cascade type and a built-in type are proposed. An experimental example is presented.

Piecewise linear controller improving its own reliability

Abstract Although the capability of neural networks in nonlinear dynamics modelling is well-established, the reliability of the output heavily depends on the training data. The reliability is a serious problem in applying it to real problems. In this paper, we propose a radial basis functions network (RBFN) which evaluates its own reliability and improves itself recursively. This network approximates the input-output relationships with a piecewise linear regression. An adaptive internal model control algorithm in which the reliability of the model is used to tune the controller performance, is also proposed.

Spread Spectrum PWM Signal Generator for Fully Digital Audio Amplifier

A generation scheme to make a low noise low distortion PWM signal spreading its spectrum for the fully digital audio amplifier is proposed. The carrier frequency of the PWM is fluctuated randomly to spread the spectrum of the carrier component. The noise-shaping filter in the delta-sigma modulator is implemented so that the filter works with a changing sampling period preserving the designed frequency characteristics. Such a filter is designed in continuous-time manner considering the distortion due to the PWM and is realized as a digital filter to compensate the effect of the sampling period fluctuation with feedback manner. A S/(N+D) ratio of over 120 dB is achieved for the generated PWM signal.

Anti-saturation discrete-time nonlinear controllers and observers

Abstract In this paper, a nonlinear controller design method based on a nonlinear state space model is proposed. By adding differentiable saturation elements, this controller design scheme can deal with the saturation of the manipulated variables. Linear approximation is successively executed at each sampling time. The velocity-type controller and observer are designed based on the linear model. For the calculation of linear approximation, the information of the states at the previous sampling time must be known. A nonlinear observer using integration of nonlinear state equations is adopted for the state estimation. The observer gain of the linear observer is applied to the nonlinear observer. This control system can stabilize open-loop unstable processes and non-minimum phase systems. The performance is demonstrated by its successful application to control problems of a CSTR, which has two stable points and one unstable steady-state point.

Pulse width and position modulation for fully digital audio amplifier

A modified pulse width modulation approach is proposed. The pulse position is modulated as well as the pulse width to have a higher resolution of the modulation. Employing a noise shaping filter with a state-space form utilizing the sliding mode scheme enables the proposed approach. The fully digital audio amplifier is selected as an application to realize a high resolution effectively.

Pulse density modulation using pulse pattern approach for zero-cross switch control

An approach of the pulse density modulation allowing a high modulation factor for the zero-cross switch control is proposed. The pulse pattern for the pulse density modulation is determined over an interval of several clock to allow a high modulation factor. The noise shaping filter is designed utilizing a continuous-time one to realize a high effective resolution of the modulation. In the presented example, the effective resolution is above 20 levels with the bandwidth of the Nyquist frequency using eight-clock pulse patterns with a third order noise shaping filter.

Low distortion digital pulse width modulation for audio class-D amplifier

A pulse width modulation scheme for a high fidelity digital audio amplifier is presented. The uniform PWM is used to utilize the over sampling technology, but the UPWM causes harmonic distortion. The harmonic distortion components at the PWM output are estimated using the derivatives of the input signal and cancelled at the input of the delta-sigma modulator. The output signal of the delta-sigma modulator is coarsely quantized with shaped noise and fed to the pulse width modulator. A simulation result for a dual tone test is presented to illustrate the effectiveness of the proposed method.

Abnormal situation correction based on controller reconfiguration

Abstract It is desirable to support operator activity in abnormal correction of chemical plants. Although fault diagnosis systems have very fertile grounds for theoretical and industrial development, multiple possibilities of faults are diagnosed. A countermeasure against one cause might be dangerous when used against another cause. A countermeasure might be effective to multiple causes. Countermeasure planning is necessary to complete fault diagnosis. An operator manipulates one variable while observing one variable in each countermeasure. It resembles the controller configuration of a single loop controller. An algorithm for controller reconfiguration is proposed for the first stage of countermeasure planning.

Model following controller with specified sensitivity function

A design method for a model-following servo control system whose output sensitivity function is specified with a reference model is presented. Using this method, the plant output responses to reference input change and the output sensitivity function can be specified separately and directly. >

Zero-cross switch control of AC resistive load with multi-cycle period delta-sigma modulator

An approach to adjust the feeding power to resistive electric heaters using zero-cross switching of the power line with delta-sigma modulator is proposed. The switch is on or off with a unit of a half cycle of the power line suppressing low frequency components of the load voltage to prevent the transformer saturation. To manage this constraint of the switching sequence, the pulse sequence for the switch is determined with a period of several cycles of the line voltage with a criterion of the noise-shaping filter in the delta-sigma modulator. As a result, the quantization noise in the lower frequency region becomes lower than the case the switch is controlled with a unit of the line cycle.