This paper introduces a practical implementation of the normalized dynamic energy stability margin (NDESM) which is simplified for wheeled mobile robots. Several types of sensors are generally required to measure the stability margin of a robot. This makes the practical implementation of a stability measurement system complicated. The simplified stability margin can be measured with only a few sensors, and it describes both static and dynamic effects on stability. The performance of the simplified stability margin is demonstrated through dynamic simulations. The experimental results and an implementation of the stability margin measurement system on a real robot are also presented.