This paper considers the experimental and numerical study of an electromechanical arm powered by a DC motor and subjected to the action of permanent magnets. The magnetic torques arise from permanent magnets mounted at the free end of the arm and along a circle. The electrical subsystem is powered by two forms of input signal (DC and AC voltage sources). For each case, we determine the condition for complete rotation of the mechanical arm versus the parameters of the system such as the arm length, the number of magnets, and the frequency of the external signal. The nonlinear dynamics of the system is examined by means of time-histories, bifurcation diagrams, Lyapunov exponents and phase portraits. Chaotic and periodic dynamics are detected numerically and confirmed experimentally.

This work analyzes an energy harvesting system made of a beam or an arm possessing a magnet at one end and moving in a circular trajectory on which two magnets are diametrically positioned. The beam is submitted to the effects of two types of excitation. The first one acts when the beam is in a prescribed angle interval and the second one is a time periodic external excitation. The generated mechanical potential energy due to the magnets is presented and discussed. The conditions for complete rotation are obtained. They depend on the external excitation amplitude and system parameters. The resulting types of motion which take place are presented. The bifurcation diagrams plotted versus different control parameters display different dynamical behaviors including chaos. The power variation in a resistive load is presented versus the value of the resistance, the amplitude of excitation and that of the magnet strength. When the magnets have strengths of the same sign, it is found that the power increases with that strength. This is an interesting result since it indicates the increase of power generated thanks to the presence of the magnets.