We propose a concept of autonomous energy transducer at a molecular scale, where output is produced by an energy input, without imposing any restriction on the magnitude or timing of input, and without any
control after the input. As an example, a dynamical systems model with several degrees of freedom is proposed, which transduces input energy to output motion on the average. It is shown that this transduction is robust and the coupling between the input and output is generally loose. How this transducer works is analyzed in terms of dynamical systems theory, where chaotic dynamics of the internal degrees of freedom, as well as duration of excited conformation of an active part which is self-organized with the energy flow, is essential.