Topic
Servo
About: Servo is a research topic. Over the lifetime, 13078 publications have been published within this topic receiving 89880 citations.
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TL;DR: In this article, a sliding-mode control method based on one novel slidingmode reaching law (SMRL) is presented, which allows chattering reduction on control input while maintaining high tracking performance of the controller.
Abstract: In order to optimize the speed-control performance of the permanent-magnet synchronous motor (PMSM) system with different disturbances and uncertainties, a nonlinear speed-control algorithm for the PMSM servo systems using sliding-mode control and disturbance compensation techniques is developed in this paper. First, a sliding-mode control method based on one novel sliding-mode reaching law (SMRL) is presented. This SMRL can dynamically adapt to the variations of the controlled system, which allows chattering reduction on control input while maintaining high tracking performance of the controller. Then, an extended sliding-mode disturbance observer is proposed to estimate lumped uncertainties directly, to compensate strong disturbances and achieve high servo precisions. Simulation and experimental results both show the validity of the proposed control approach.
518 citations
TL;DR: Muscular movements are under the control of a servo similar in many ways to those used in engineering control systems but with a subtlety of design not found in man-made servo mechanisms—including an automatic gain compensation for altered load which must be useful for adjusting to reduced g on the Moon.
Abstract: Muscular movements are under the control of a servo similar in many ways to those used in engineering control systems but with a subtlety of design not found in man-made servo mechanisms—including an automatic gain compensation for altered load which must be useful, for example, for adjusting to reduced g on the Moon.
378 citations
TL;DR: In this article, the robust control of a general servomechanism problem is considered and sufficient conditions for asymptotic tracking to occur, independent of disturbances in the plant and perturbations in the parameters and gains of the system, are obtained.
377 citations
Patent•
IBM1
TL;DR: In this article, a track following servo system is described for magnetic tape systems in which magnetic servo track patterns contain transitions recorded at more than on azimuthal orientation across the width of the servo tracks.
Abstract: A track following servo system is disclosed for use with magnetic tape systems in which magnetic servo track patterns contain transitions recorded at more than on azimuthal orientation across the width of the servo track. The timing of a signal derived from reading at any point across the width of such a pattern varies continuously as the read head is moved across the servo track. The pattern is read by a servo read head whose width is small compared to the servo track pattern. The combination of a wide servo pattern and a narrow servo read head offers excellent position sensing linearity and dynamic range. In the preferred embodiment, the servo read head is also narrow with respect to the data tracks, which provides the additional advantages of superior immunity to position sensing errors caused by defects or temporal variations in the servo read head, defects in the servo pattern on the tape, wear of the head or tape, or debris collection on the head or tape. Position sensing with this system is achieved by deriving a ratio of two servo pattern intervals and therefore is insensitive to tape speed during reading. The servo patterns may include spacing intervals recognizable for error detection and correction purposes. Servo tracks are recorded using a patterned multiple gap servo write head whose magnetic gaps have geometries appropriate to generate the desired servo patterns. The patterned gaps of the servo write head are produced by photolithographically defined electroplating of permalloy on a ferrite ring head structure.
320 citations
09 Apr 1991
TL;DR: A visual feedback control scheme, called image-based visual servo, is proposed for manipulators with cameras on their hands that is stable even under noisy conditions, while the conventional position-based servo tends to be unstable.
Abstract: A visual feedback control scheme, called image-based visual servo, is proposed for manipulators with cameras on their hands. To accomplish specific tasks in unstructured environments, it is essential to have capabilities of recognizing the object position with respect to the manipulator hand. Using the Jacobian matrix relating the camera motion to the object position change in the acquired image, a state space formulation of a visual feedback system is established. On the basis of the task defined in the image plane, the desired motion of the hand is achieved by time-variant state feedback. The image-based scheme is applied to a task of tracking a moving object by the camera (and the hand). Simulations show that the control scheme is stable even under noisy conditions, while the conventional position-based servo tends to be unstable. Experiments on a PUMA 560 show the validity and the effectiveness of the image-based visual servo. >
320 citations