In this paper, we propose a design of output consensus control systems for heterogeneous discrete-time Multi Agent Systems (MASs). In the proposed method, Parallel Feedforward Compensator (PFC) is added to agents to have Almost Strictly Positive Real (ASPR)-ness, and Simple Adaptive Control (SAC) is used theory. The proposed method to achieve output consensus for MAS is designed in two main steps. First, the control law of the reference models to be followed by the agents is designed to achieve the output agreement of the reference model. Next, using SAC theory, the control law of the agents is designed so that the outputs of the agents follow those of the reference models. With the above design, the proposed method pursues tracking performance while simultaneously compensating for stability. Finally, numerical simulations are performed to demonstrate the effectiveness of the proposed method.

Data science has been attracting a great deal of attention in recent years because of its promise to extract value from the data that abounds in society. In the control engineering field, data-driven design, in which control system design can be performed directly from data, can also be considered a part of data science. Using the data-driven approach, a control system can be optimized directly from controlled data. However, even if a system is optimally designed, its behavior cannot be verified until the system is actually controlled. Therefore, in the present study, a data-driven response estimation-based tuning (DRET) is proposed in order to design a control system based on the estimated time response. It is applied to the control system design of not only stable systems but also unstable systems. In the design of DRET, a finite impulse response filter is used and a model matching problem is solved directly from the control data, to compensate for the difference between an original objective function and a data-driven objective function. The proposed method is applied to the control system design of a ball-and-beam system, which is an unstable system, and its usefulness is verified.

Cascade control structures are widely implemented in industries, due to the fact that they increase the performance of single-loop control. Nevertheless, their implementation requires a higher initial investment. Because of this, it is of great importance to be able to quantify their relative performance improvement. Very few studies handle this subject, and they do not obtain results which directly establish this quantification on a general basis. Therefore, the objective of this project is to conduct a study with help of computational tools, in order to determine the relative performance improvement of a cascade control structure with respect to a single-loop structure, for setpoint tracking and disturbance rejection. An overdamped second-order-plus-dead-time process, separable in two first-order-plus-dead-time subprocesses, was considered. The controllers were implemented using a PID algorithm. Simulations were conducted to obtain the ratio of the IAE performance indexes of each control structure, as a function of the time constant ratio, for different process parameters. The controllers were tuned by means of optimization routines, in order to guarantee that they provided the best IAE index. Finally, two general equations were obtained, which quantify the relative performance improvement of a cascade control structure with respect to a single-loop structure, as a function of the process parameters, for set point tracking and disturbance rejection.

Multi-agent systems (MASs) are used for distributed control purposes and substantial research attention has been directed to these systems because of their practical merits. In MASs, agents' information is shared through networks. In networked-control systems, the measured data is usually quantized because of sensor performance or specification, and its resolution is inadequate. Furthermore, because of network quality, the measurement interval is often longer than the control interval. Therefore, the present study introduces a design method for a dual-rate quantized control system, in which the measurement interval of agents is an integer multiple of the control interval.

The present study discusses a data-driven control method for the single-input single-output (SISO) dual-rate control system, in which the sampling interval of the plant output is shorter than the holding interval of the control input. Using the lifting technique, the SISO dual-rate system is converted to the single-input multi-output (SIMO) single-rate system, where the sampling intervals are the same as the holding interval, and the controller parameters are optimized using only the open loop data. Finally, the effectiveness of the proposed method is demonstrated through numerical examples.

This paper gives an optimal control law to eliminate ripples in inter-sample intervals of transient state of multi-rate sampled-control systems. As for ripples in steady state, there already exist several methods to remove the ripples. But to reduce the ripples in transient-state, so far there exists only trial and error method and there does not exist a systematic method. In this paper, first a reference model is defined which generates a reference output with no ripples and at sampled points, it has the same outputs with continuous time multi-rate control systems. Then the ripples in transient state are measured by the integrals of squared output errors. And equations to calculate the integrals are given by solving of Lyapunov equations. Finally the optimal control law is derived by differentiating the equations by the control input. The obtained optimal control input has a state feedback form and can be calculated at the short sampling time.

The present study proposes a design method for a single-input single-output dual-rate control system, in which the sampling interval of the plant output is twice the hold interval of the control input. In such a dual-rate control system, intersample ripples might occur even if the discrete-time response converges to a reference input because the control input can be updated between sampling intervals. The present study proposes a new design method for eliminating the intersample ripples without changing a pre-designed discrete-time response. In the proposed method, a pre-designed control law is extended using redundant input in the dual-rate control system, and the intersample response is enhanced independent of the discrete-time response.

In the present study, we propose a design method for a dual-rate control system, in which the sampling interval of the plant output is twice the hold interval of the control input. Noniterative correlation-based tuning (NCbT) has been proposed in a single-rate system, in which both the intervals are same. In NCbT, a controller parameter is optimized using a set of input-output data when the plant model is unknown. In the present study, we extend NCbT to a dual-rate control system. Finally, the effectiveness of the proposed method is demonstrated through a simulation example.

In this study, a nonlinear system is controlled using a linear adaptive method. A nonlinear system is approximated a linear model at each operating point, and a control law is designed based on the approximated linear model. To obtain a suitable linear model at each operating point, many linear models are simultaneously identified. However, the computation load for identifying many models is considerably heavy. Hence, many linear models are identified using General-Purpose computing on Graphics Processing Units (GPGPU). In this study, the assessment of modeling performance is newly introduced. As a result, the control system is updated only when modeling performance is degraded, and frequent update of a control law can be avoided. Finally, numerical results are shown to demonstrate the effectiveness of the proposed method.

This paper proposes a new design method for a drum boiler system, which is a benchmark problem for PID control. The boiler is a multi-input multi-output (MIMO) system with interference, but it is divided into independent single-input single-output (SISO) systems. In the proposed method, interference is considered a disturbance, and a controller is designed for each system. Because the controlled plants are time-varying systems, the control system is adaptively updated based on generalized minimum variance control (GMVC).

This paper presents measured results of dynamic voltage drop caused by pulse and periodic injection of spot noise. The test structure being fabricated by a 45 nm low-power process has 1024 delay probes to measure spatial distributions in response to the spot-noise generation. The test structure is the advanced version of our predecessor being fabricated by a 65-nm node, and can trace changes in the spatial distributions with time after the noise injection. The measured results are compared with SPICE simulations, in which package/socket LCR as well as power-line RC within the die is modeled. It is found that the simple model agrees well with the measured results.

This paper describes observations of supply-voltage-noise dispersion by using a test structure fabricated with a 65-nm low-power process. The test structure can capture the phenomenon in two domains: One is a space domain. The 1 kbit probes distributed uniformly over the entire test-module region detect the spread of the noise, which is induced in the center of the module. The noise is generated by simultaneous activation of 8 kbit flip-flops (FF), which are placed in a dense area. Each delay probe consists of a short buffer-chain between a pair of FFs to detect the delay shift caused by voltage drop in the area. The other is a time domain. The probes being different in the length of the buffer-chains can capture the time dependency. The measurement results have revealed how the supply-voltage-noise spreads over the entire test-module region in a very short time (sub-nsec).

This paper presents a clock-skew test module for exploring reliable clock distribution under process, voltage, and temperature (PVT) variations. The proposed test module enables direct evaluation of the following two important issues: 1) the clock-skew process variations and 2) the robustness against race problems under environmental variations such as voltages and temperatures. The test module was fabricated by using a 90-nm low-power process for system-on-chip (SoC). It contains eight blocks including H-tree blocks and clock tree synthesis (CTS)-tree blocks (i.e., blocks formed by clock-tree synthesis), each of which has 1024 flip-flop (FF) pairs with small hold-time margins. A statistical method has been developed for analyzing the measured hold-time margins of the 1024 FF pairs for 80 chips. The example of the analysis for the measured results is presented, confirming the effectiveness of the proposed test module and analysis method toward reliable design of clock distribution.

Viewing environment is an important factor to understand the mechanism of visually induced motion sickness (VIMS). In Experiment 1, we investigated whether the symptom of VIMS changed depending on viewing angle and physical display size. Our results showed that larger viewing angle made the symptom of sickness severer and nausea symptom changed depending on physical display size with identical viewing angles. In Experiment 2, we investigated effects of viewing angle and amplitude of oscillation. The results showed that the effects of viewing angle were not only related to amplitude of oscillation but also to the other factors of viewing angle.

We examine whether visual motion induces a sensation of motion for a static sound in order to investigate dynamic visual-auditory interactions in the virtual environment. The dynamic interaural time difference (ITD) was employed as the cue for sound motion, and the effect of the size of the visual stimuli on biasing the perceived direction of dynamic ITD was examined As a result, induced motion sensation for static sound was obtained, and its direction was dependent on the size and direction of the applied visual stimuli. For a small visual stimuli (an 1-deg disk), sound with a static ITD moved in the same direction as the moving visual stimuli. For a large visual stimuli (a 90-deg random-dot pattern), however, sound with a static ITD moved to the opposite direction to that of the moving visual stimuli.