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Noncollocated sensors and actuators, and/or fast sample rates with plants having high relative degree, can lead to nonminimum-phase (NMP) discrete-time zero dynamics that complicate the control system design. In this paper, we examine three stable approximate model-inverse feedforward control techniques, the nonminimum-phase zeros ignore (NPZ-Ignore), the zero-phase-error tracking controller (ZPETC),...
The IEEE Control Systems Society was established in 1954 and thus celebrates its fifty-fifth anniversary as the IEEE celebrates its 125 this year. As part of that celebration, we have compiled an overview of the history of this group. This paper will tell the story of the society as we have gleaned it from those who were around when it was founded, and who played critical roles in the development...
Students studying control problems often learn a lot of wondrous algorithms that impart near mythical properties to the systems that they are applied to. At least this is how it works in theory and simulation. In practice, however, a thorough understanding of the system, the use model, and the market is often far more important than the differences between any two optimization algorithms. Knowing...
Although phase-locked loops (PLLs) are arguably the most ubiquitous control loop designed by humans, system theory analysis seems to lag behind the practice of implementation. In particular, full simulation of PLLs is rare. This paper will explain the reasons for this and offer an efficient and flexible simulator for PLLs. This part presents the simulator requirements and design. Part II presents...
The control of a typical commercial Atomic Force Microscope (AFM) is through some variant on a Proportional, Integral, Derivative (PID) controller. Typically, the gains are hand tuned so as to keep the bandwidth of the system far below the first resonant frequency of the actuator. This paper shows a straightforward method of selecting PID gains from the actuator model so as to allow considerably higher...
Noncollocated sensors and actuators, and/or fast sample rates with plants having high relative degree, can lead to nonminimum-phase (NMP) discrete-time zero dynamics that complicate the control system design. In this paper, we examine three stable approximate model-inverse feedforward control techniques, the nonmimimum-phase zeros ignore (NPZ-Ignore), the zero-phase-error tracking controller (ZPETC)...
The atomic force microscope (AFM) is one of the most versatile tools in nanotechnology. For control engineers this instrument is particularly interesting, since its ability to image the surface of a sample is entirely dependent upon the use of a feedback loop. This paper will present a tutorial on the control of AFMs. We take the reader on a walk around the control loop and discuss each of the individual...
Images in atomic force microscopy (AFM) are built pixel-by-pixel through a raster scan process and can take on the order of minutes to obtain. The problem of imaging a sample can be characterized as using a short-range or point-like sensor to obtain information about a system over a region and is common across a broad range of fields in science and engineering. In many cases, as in most AFM images,...
The atomic force microscope (AFM) is a powerful imaging and nanofabrication tool that allows the user to observe and manipulate samples at the atomic level. However, one limitation of current AFMs is the long time required to obtain a quality image of a sample. Several researchers have investigated this problem in recent years, and we give an overview of the approaches explored, including Hinfin,...
Small disk drives are inherently designed for portable applications and thus must be able to reject external shock and vibration. This paper expands on previous efforts at using the signal from a rotational accelerometer to minimize the effects of these disturbances by dealing with several issues that come up: accelerometer beam resonances, low sample rate of the embedded servo on the disk drive,...
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