| 1. |
- Ding, Limei, et al.
(författare)
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Application of fuzzy control to a flotation process
- 1999
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Ingår i: Elsevier IFAC Publications / IFAC Proceedings series. - Kildington : Elsevier. - 1474-6670. ; 32:2, s. 6998-7003, s. 391-396
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Tidskriftsartikel (refereegranskat)abstract
- The application of fuzzy logic in the control of flotation is studied in this paper. A general description of apatite flotation process is given and a dynamic model is developed. A fuzzy logic controller is proposed for a nonlinear isolated continuous flotation process. The knowledge base of the controller is constructed on the basis of the semi-batch results from the apatite flotation experiments and available knowledge sources. The design of the controller does not need an exact process model. The simulation result shows that the fuzzy logic controller can reduce collector dosage consumption of the apatite flotation process while maintaining the phosphorous content in magnetite concentrate within an acceptable limits less than 0.025% P. Stability of the fuzzy control system is discussed
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| 2. |
- Fischer, Britta, et al.
(författare)
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Control Relevant Identification in H∞ - Adaptive Information and Experiment Design
- 1996
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Ingår i: Elsevier IFAC Publications / IFAC Proceedings series. - 1474-6670. - 0080429084 ; 29:1, s. 4046-4051
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Tidskriftsartikel (refereegranskat)abstract
- Joint issues of modelling and control design are studied in a frequency domain setup. Stable systems with monotone Bode plots are chosen as the basis of the study presented in this work. Such dynamics is typical for plants in industrial process control. Adaptive information is considered and both open-loop and closed-loop experimental conditions are included. For systems with monotone Bode plots the information typically required for successful control design consists of a small part of the frequency response only. This can be exploited in experiment design.
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| 3. |
- Fischer, Britta, et al.
(författare)
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Laguerre domain estimation of time delays in narrowband ultrasonic echoes
- 1999
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Ingår i: Proceedings of the 14th World Congress. - Kildington : Publ. for the International Federation of Automatic Control by Pergamon. - 1474-6670. - 0080432190 ; , s. 361-366
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Konferensbidrag (refereegranskat)abstract
- The time delay of arrival (TDOA) is required in many areas in signal processing. In this paper we propose a novel and straightforward method to estimate small continuous time delays in narrowband signals out of a sampled sequence of the input and output signals. It is based on the parameterization of the identification problem in the Laguerre functions. An lp norm optimal estimator is then applied to estimate the delay. Furthermore, estimation bounds are studied and experiments from ultrasonic applications are presented to highlight the performance of the method
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| 4. |
- Forsberg, Johan, et al.
(författare)
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An autonomous plastering robot for walls and ceilings
- 1995
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Ingår i: Elsevier IFAC Publications / IFAC Proceedings series. - Oxford : Pergamon Press. - 1474-6670. - 0080423663 ; 28:11, s. 301-306
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a robot and algorithms for autonomous spray plastering of walls and ceilings during the construction of apartment houses. Successful experimental tests are described where the robot measures the size of the room and the location of doors and windows. The work sequence is then planned and executed autonomously. To sense the environment the robot uses a range measuring scanning laser. The range weighted Hough transform is used to observe the walls and the resulting observations are used to update estimates in an extended Kalman filter based map. Association of observations to estimates is performed using the estimated probability of a correct match, taking correlations between estimates into account when needed.
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| 5. |
- Hillerström, Gunnar, et al.
(författare)
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Repetitive control theory and applications : a survey
- 1996
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Ingår i: Elsevier IFAC Publications / IFAC Proceedings series. - 1474-6670. - 0080429084 ; 29:1, s. 1446-1451
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this paper is to present repetitive control, controllers for rejecting periodic disturbances or tracking periodic reference signals, This survey covers both continuous and discrete time theory, together with a number of applications
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| 6. |
- Högström, Tomas, et al.
(författare)
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On Segmentation, Shape Estimation and Navigation Using 3D Laser Range Measurements of Forest Scenes
- 1998
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Ingår i: Elsevier IFAC Publications / IFAC Proceedings series. - 1474-6670. - 0080429297 ; 31:3, s. 423-428
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Tidskriftsartikel (refereegranskat)abstract
- The problem addressed is segmentation and shape estimation of three-dimensional laser range measurements of forest scenes. For each tree the position as well as the three dimensional shape of the trunk is estimated. The detection uses a two-dimensional histogram of the measurements, followed by segmentation by fitting cylinders around the measurements of each detected tree trunk. The shape estimation consists of fitting a 3D spline to each tree trunk's centre curve and computing the trunk width by extracting the range discontinuities at the edges. For the experiments a mobile robot carrying a scanning laser range finder was used. Navigation was done by matching the extracted tree trunk positions from subsequent range scans, determining the relative movements
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| 7. |
- Högström, Tomas, et al.
(författare)
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Telecommands for Remotely Operated Vehicles
- 1995
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Ingår i: Elsevier IFAC Publications / IFAC Proceedings series. - 1474-6670. - 0080423663 ; 28:11, s. 301-306
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Tidskriftsartikel (refereegranskat)abstract
- The problem addressed is controlling a robot over a communication channel with low bandwidth, a non-neglectable time delay and time jitters. The external sensors on the robot are a time-of-flight range measuring laser and a video camera. Video images are used by the operator for interpreting the scene and are only sent at “fax rate”. The operator is thus interpreting the workspace around the vehicle, making plans for the individual operations in a composite task and is giving high level commands. The telecommands are to be executed autonomously by the robot. Inside the robot the control loop is closed with full bandwidth when each command is executed.This paper reports on work in progress and focus on:1. Incremental map building, especially simplifications for large buildings and robustness when the vehicle returns to a previously mapped area. This is a very useful support function for the operator.2. Tests of telecommands on a mobile robot available for experiments over the Internet. Available sensors are inclinometers, odometry, CCD intensity images and range measuring laser data.Other needed telecommands studied previously are:Travelling along corridors, follow walls etc. The operation is based on the range weighted Hough transform and is both robust and precise. The repeatability is about 1 cm at 1 m/s. The robot is not disturbed by people passing in the corridor.Commands for passage through an open door works within 1 cm and 0.5 degrees at a speed of 0.5 m/s. Passing between irregular obstacles is less accurate.Using rate gyros, lock the heading of the robot when driving on a straight line. Also preprogrammed 90- and 180-degrees turns.Automatically enter a camera defined line. The direction of the camera can be used to drop a new coordinate frame at any time (using a button on the keyboard). The robot will automatically enter this new line and also compensate for the overshoot.To integrate these different commands into a complete system is a resource demanding task for the future.
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| 8. |
- Larsson, Ulf, et al.
(författare)
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On rate gyros for improved navigation by reducing dead-reckoning errors
- 1998
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Ingår i: Elsevier IFAC Publications / IFAC Proceedings series. - Oxford : Pergamon Press. - 1474-6670. ; 31:3, s. 207-212, s. 207-212
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Tidskriftsartikel (refereegranskat)abstract
- Consider a vehicle using a number of landmarks for navigation. Between the observation of the landmarks, the motion of the vehicle is estimated using internal sensors like odometers and rate gyros. The output from a dead reckoning algorithm is used in a Kalman filter and/or used to make association of observed landmarks. In such a system the accuracy of the dead reckoning algorithm is essential for the overall performance. In the paper `slip angles' at the wheel-surface contact point are included in the kinematic model. The slip angle is assumed to be essentially proportional to the side force. The topics considered in the paper are: dead reckoning model with a slip angle; improved dead reckoning when a rate gyro is used; and equations for comparing the error growth. Four different algorithms for dead reckoning are studied and compared. Two of them just model the slippage and two of them are based on more accurate measurements of rotation, using a rate gyro
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| 9. |
- Medvedev, Alexander
(författare)
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Disturbance attenuation in finite spectrum assignment controllers
- 1996
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Ingår i: Elsevier IFAC Publications / IFAC Proceedings series. - : Elsevier. - 1474-6670. ; 29:1, s. 1620-1625
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Tidskriftsartikel (refereegranskat)abstract
- Two finite-spectrum-assignment controllers for continuous linear dynamic systems with multiple time delays in input signal are introduced. The controllers are shown to comprise least-squares state estimators. Disturbance attenuation properties stipulated by the choice of shift operator in the observers are studied.
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| 10. |
- Medvedev, Alexander
(författare)
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State estimation and fault detection by a bank of continuous finite-memory filters
- 1996
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Ingår i: Elsevier IFAC Publications / IFAC Proceedings series. - : Elsevier. - 1474-6670. ; 29:1, s. 6542-6547
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Tidskriftsartikel (refereegranskat)abstract
- A continuous observer estimating the state vector of a linear time-invariant system from the measurements of the system's inputs and outputs passed through a bank of finite-memory filters is introduced. System observability is shown to guarantee the existence of the observer. An application of the observer to the problem of detecting and isolating sensor and actuator faults is discussed
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