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Systems with structural resonances are difficult to control if fast responses are required. Rapid changes in the control signal may excite the resonant modes. In digital control with zero-order-hold sampling there will be very rapid changes in the control signal. A way to deal with the problem is to use predictive first-order-hold sampling instead. The control signal is then linear between the sam
Automatic control is increasingly used in mission critical applications. The reason for this is the potential benefits and the fact that control engineering is now able to deal with complex systems. Control of high performance aircrafts is a typical example. Considerable benefits can be obtained by having an aircraft that is unstable in certain flight conditions and providing stability with a cont
Volvo Excavator AB has problems controlling the number of revolutions per second, in the diesel engine of an excavator, when it is running. To solve this problem the different processes controlling the energy flow in an excavator are mathematically identified. These models are later put together to enable simulations of a running excavator on the computer. The different models that need to be iden
A water jet is a propulsion system for vessels. The principle of water jet is to admit water into the hull, then add head to the water via the impeller and then let the water go through a guide vane package and then discharge it at the stern. The reaction force will bring the vessel into motion.
KaMeWa Group, a Vickers company who manufactures water jet propulsion systems, initiated the work.
The object of this thesis is to explore of a planar, almost circular amoeba, can move efficiently in an inviscid fluid. We investigate a homogenous amoeba and a heterogeneous amoeba and find that motion is possible for both using the physical fact that more work is needed when moving a bulky body in a fluid than when moving a small body of the same mass. For our calculations to be valid only small
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
