Please make sure that you have tried first those questions before looking into the correct answers.
This is the basic question to categorise a control system. Definitely the correct answer depends on the type of signals the system processes. The range of times when the system was developed and/or the response time of the system are totally irrelevant
Return to Question 1The fundamental result of a hybrid control system simultaneously complies with both logical and continuous-time constraints. There is no priority of which constraints must be complied with first. The reaction which is taken is not necessarily independent from both constraints. In controlling the water level of a tank as an example,(please refer to Ahmad Kamil's Article2 ) only ONE reaction is enough which is to turn the tap at an appropriate angle.
Return to Question 2The incorrect choice is ii. A hybrid control system is actually trying to reduce the response time. This can be done by converting a logic control system to be hybrid. Please refer to questions 4 and 5 for more details of this conversion.
Return to Question 3It is true that hybrid systems are the latest in control technology but generally it is still under development. In addition, converting into a hybrid control system does not make more effective a particular system especially when the system has very few conditions or situations to be considered. Using a logic control system in this case is better. Furthermore, a hybrid control system is relatively less reliable and less economical (refer to question 1). From the given text, for a logic control system to be more effective, more logic rules need to be added in the machine's database that, on the other hand, will increase the response time. Converting into a hybrid is then necessary.
Return to Question 4
The right steps of the conversion are
Return to Question 5Actually all alternatives can be implemented using a mixture of discrete and continuous control systems i.e. a hybrid. Unstable very high performance systems such as the above alternatives will benefit from the flexibility of hybrid systems, since different control laws can be imposed to make the system behave acceptably in successive time intervals[2].
Return to Question 6Combining logic and continuous systems requires the knowledge of a variety of mathematical and engineering disciplines such as differential geometry, automata(programs) theory, differential and difference equations, optimal control, discrete event systems, data structures and computation[2]. A unified theory did not exist at all 10 years ago. Hybrid systems is currently an active area of research in control theory and computer science but a fully mature theory is still a few years off.
Return to Question 7Anil Nerode and Wolf Kohn have proposed MAHCA[1] which is based on extensions to the theory of relaxed variational control. Basically, they use this relaxed calculus of variations to extract finite control automata, which guarantee an approximately optimal performance.
Return to Question 8First of all the interaction of logic and continuous elements in real system can not be decomposed into disjoint logic and continuous elements. A discrete system is a very special case of a hybrid systems. The procedure of discrete systems can be continualised with improved performance advantages.
Return to Question 9They allow for the improvement on the traditional control and estimation technologies by providing computationally effective methodologies for the implementation of digital programs that design or modify the control law in response to sensor detected events, or as a result for adaptation and learning.
Return to Question 10A.Nerode and W.Kohn proposed method(MAHCA)[1] on complex optimization problems. They developed a Computer-Aided Control Engineering(CACE) architecture to solve the disagreement between different disciplines over the development of control systems. They arranged the responsibilites of the players in the solution of control engineering.
Return to Question 11