Qualitative reasoning about control

Qualitative models are better suited for some tasks than the traditional quantitative, or numerical models. These tasks include diagnosis, generating explanation of the system´s behavior and designing novel devices from first principles. It is shown by an example how a qualitative modeling approach can be applied to the control of a dynamic system. The example used is the balancing of a pole on a cart. A control rule is derived from a qualitative model of the pole-and-cart system. This rule is shown to be a straightforward qualitative abstraction of the “classical” control rule derived from the differential equations model of this system