In this paper, a 2-degree of freedom dynamic model of an unbalanced rotary engine is designed, in a manner that has the effect of modal coupling. After designing the dynamic model in order to reduce the vibrations generated due to the unbalancing mass and modal coupling, the active force control (AFC) method is implemented along with a conventional proportional integral derivative (PID) controller with linear actuators, meaning that the AFC loop is applied as a supplement to the conventional PID controller. The obtained results show that, when the AFC loop was engaged with the PID controller, the vibrations were reduced to nearly zero in both aspects of frequency and amplitude when compared to the case in which only a PID controller was operating in the control system.

In this article, the Active Force Control (AFC) method is implemented for reducing the vibrations that are caused by an unbalanced rotary engine. By using Matlab Simulink, the dynamic model of an unbalanced rotary engine was simulated. Then a Proportional-IntegralDerivative PID controller with the AFC loop was added. The obtained simulation results proved that when the PID controller was operating without the AFC loop, the vibrations were reduced but with very less efficiency when compared to the case in which the AFC loop was engaged with the PID controller. This means that the amplitude of vibrations was extremely reduced when the PID controller was equipped with the AFC loop, and the same results were observed for the frequency domain case. The robustness of the AFC method was also tested and again the method of AFC was very capable in reducing the vibrations.

Vibration is a physical phenomenon involving repeated oscillatory movements or fluctuations at certain frequency and typically undesirable in many applications since it may cause undue failure or damage to the system. In this paper, the vibration of a three degree-of-freedom (DOF) model representing a short length drive shaft has been effectively and robustly suppressed through the implementation of a novel Active Force Control (AFC) used in conjunction with a classic proportional-integral-derivative (PID) controller. The shaft vibration caused by its support and constraint during its operation was simulated using MATLAB and Simulink considering a number of operating and loading conditions. The results proved that when a pure PID controller was implemented, the vibration is indeed reduced but at the expense of longer execution time and producing noticeable frequency oscillation with slight offset. On the other hand, when the AFC loop was engaged by adding it directly in series with the PID controller (PID+AFC) to produce a 2 DOF controller without any need to further tune the PID controller gains, the vibration is significantly reduced with the amplitude hovering a zero datum without any offset and yielding an extremely low frequency trending.