This study is to introduce concepts of energy and entropy to describe a robnot's emotion decision.It chooses the dimensinal approach based on factors of pleasure and arousal for the merit of the interpolation between emotions.Especially,Circumplex model which has also two axes:pleasure and arousal is used.Besides,the model indicates how emotions are distributed in the two-dimensional plane.Then by the definition of psychodynamicsthe energy states (mental energy and physical energy) are matched to pleasure and arousal respectively that are the basis of Circumplex model.The mental energy is updated by the result of Prospect theory which measures the value of gain and loss as pleasure factor.And the physical energy is updated by the result of hedonic scaling which measures levels of arousal from pleasure computed by Prospect theory,and the result of intensity of stimuli.Then the energy states are fed by entropy.The feedback loop by entropy satisfies the 2nd law of thermodynamics.The energy states generated by stimuli and fed by entropy take a position in the plane of Circumplex model.Then distances between the current position and other emotions are computed to get a level of each emotion,proportional to the inverse of the distance.