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Backlash is common in mechanical and hydraulic systems. It severely limits the overall system performance. Many mechanical solutions have been developed to overcome backlash, for example by using spring-loaded split gear assemblies or dual motor systems. These mechanical solutions can satisfactorily handle the backlash problem but they give rise to other problems like decreased accuracy and reduce
Backlash is often present in mechanical transmission systems and can be one of the main causes that severely limits control systems performances. In this work are presented a number of adaptive algorithms that through a proper feedforward nonlinear action try to compensate the backlash. Due to the nonlinear nature of the problem, convergency proofs are very difficult; nevertheless simulations show
In order to analyse the human postural control system single-stimulus multi-response measurement experiments are made, where the body sway due to an induced disturbance on the calf muscles are recorded with force platforms, Selspot systems or EMG-equipments. The measured outputs are usually analysed one by one as for a Single-Input Single-Output system. In this study a Single-Input Multi-Output ap
Industrial robots are used/configured/programmed by several different types of users/programmers. The control system should preferably expose a uniform view for each programming situation. Such views were defined by the Open Robot Control (ORC) architecture, developed within the department in an earlier project. This project refines and evaluates some robot programming principles. First, earlier p
This paper describes three improvements for a PID controller. These improvements have been created with SattLine, which is an object-oriented, distributed process automation system developed by Alfa Laval.
These improvements are a compensator for static friction in control valves, an interpolation between the PID values when the system is non linear and the creation of a table to save di
Friction modelling is a delicate problem which poses several challenges to control engineers. This work focuses on two recent models which describe friction with nonlinear dynamical systems: The Lugre model, and the model of Bliman & Sorine. Comparisons are made concerning friction phenomena captured, computational issues, identification of model parameters and behaviour at zero-crossings of t
This thesis investigates frictional effects on the stabilization of a rotating inverted pendulum. Because of friction, limit cycles arise when trying to stabilize the inverted pendulum. The stabilization is done using linear state feedback. For estimation of the states, Kalman filters are used. Both real-time experiments and simulations are performed. Two friction models are used, one classical wi
This report is a study on placement of accelerometers in a rolling missile. A Kalman filter is used for estimation of some states of the rolling missile. The rolling angle is assumed to be known. The states are fed back to give the missile desired dynamics. Reference signals in the form of desired accelerations are also introduced.
The report shows that one transverse measuring accelerome
Recent years intensive measures of land-based emissions have increased the share contributed from ships and other marine activities. The main problem here is the nitrogen oxides emitted from today's fuel-optimized diesel engines used by the majority of ships. ABB Fläkt Marine is one of the very few companies that provides a solution to emissions on nitrogen oxides. This is made with a techniqu
Facilities to present simulation results as animations on the Internet have been developed. They can take simulation results from the modeling and simulation environment Dymola and convert them to a Virtual Reality Model Language (VRML) representation, which is the new Internet protocol for displaying three dimensional graphical worlds with sound effects. Mathematical models for sound have been de
The possibility of supervising controllers in buildings with the help of Internet and Java is investigated. The task is to develop a computer system with necessary software that enables connection over Internet from a client computer to a server computer that contains information about the controllers in a data base. It should be possible to study values and attributes of the controllers. Java and
