Open-loop controller

About: Open-loop controller is a research topic. Over the lifetime, 16148 publications have been published within this topic receiving 224014 citations. The topic is also known as: non-feedback controller & open-loop control law.

Digital controllers for SISO systems: a review and a new algorithm

Abstract: Several digital control algorithms for linear single-input single-output systems are examined and the effect of the sampling period on their performance is analysed in terms of rippling, overshoot and settling time. The problem is addressed in the frequency domain (z-transform) and it is shown that each controller works for some classes of systems but that none works for all. The similarities and differences of these controllers are established and an explanation of their deficiencies is given based on the location of the zeros of the discrete system. The insight gained leads to a simple new rule for the design of a controller which combines the advantages of the different algorithms but at the same time is free of their problems. A single tuning parameter is included which directly affects the closed-loop speed of response and bandwidth. The parameter can be used to detune the controller in the event that the real system differs from the model on which the controller design is based. No tuning is necessa...

Low-Order Stabilization of LTI Systems With Time Delay

Abstract: This paper considers the problem of stabilizing a single-input-single-output (SISO) linear time-invariant (LTI) plant with known time delay using a low-order controller, such as a Proportional (P), a Proportional-Integral (PI), or a proportional-integral-derivative (PID) controller. For the SISO LTI system with time delay, the closed-loop characteristic function is a quasipolynomial that possesses the following features: all its infinite roots are located on the left of certain vertical line of the complex plane, and the number of its unstable roots is finite. Necessary and sufficient conditions for the stability of LTI systems with time delay are first presented by employing an extended Hermite-Biehler Theorem applicable to quasi-polynomials. Based on the conditions, analytical algorithms are then proposed to compute the stabilizing sets of P, PI and PID controllers. The resulting characterizations of the stabilizing sets for P, PI and PID controllers are analogous to the Youla parameterization of all stabilizing controllers for plants without time delay. Numerical examples are provided to illustrate the proposed algorithm.

Ultra-compact, high performance motor controller and method of using same

Abstract: Featured is a controller for a motor that is ultra-compact, with a power density of at least about 20 watts per cubic cm (W/cm 3 ). The controller utilizes a common ground for power circuitry, which energizes the windings of the motor, and the signal circuitry, which controls this energization responsive to signals from one or more sensors. Also, the ground is held at a stable potential without galvanic isolation. The circuits, their components and connectors are sized and located to minimize their inductance and heat is dissipated by conduction to the controller's exterior such as by a thermally conductive and electrically insulating material (e.g., potable epoxy). The controller uses a single current sensor for plural windings and preferably a single heat sensor within the controller. The body of the controller can also function as the sole plug connector.

Machine process controller

Abstract: The controller includes a power sensing device which monitors the instantaneous power drawn by the machine and compares it with a predetermined limit level of desired power consumption. A user programmable timer is manually accessible for loading a selected time delay period therein. The controller provides an output capable of altering the machine operation when the machine power consumption has continuously exceeded the limit value for the selected time period. The controller outputs may be latched or nonlatched once an overlimit condition is detected in accordance with a user selectable programmed parameter. In an adaptive mode, the controller forces the feed rate to a programmable feed rate for a selected period of time upon initial impact between the workpiece and the machine tool. The controller then maintains a normal adaptive power level in which the feed rate response may be selectively altered as a percentage of an exponential function of the difference between the actual machine power consumption and the programmable desired adaptive power level. Provision is made for automatically referencing the feed rate control signal to the voltage rating of the feed rate drive motor in the machine.