The virtual tuned mass damper for adaptive vibration absorption on a flexible joint robotic arm

Lightweight design is widely adopted in mechanisms and robots to reduce sizes, costs and energy consumption. This yields to flexible systems, that are prone to vibrate, thus remarkably deteriorating their performances. The problem is overcome through advanced vibration control schemes. In this paper, the Adaptive Virtual Tuned Mass Damper (AVTMD), i.e., a controller whose action mimics the force of a TMD installed in the system, is exploited to absorb the vibrations arising on an underactuated two-link flexible joint robotic arm affected by an external harmonic disturbance with changing frequency. This occurrence is handled through a frequency tracking algorithm adopted to estimate the frequency used for the online tuning of the AVTMD. No a-priori knowledge of the frequency is required. The controller is tuned to assign an antiresonance at the disturbance frequency to suppress the unwanted vibrations. The effectiveness of the frequency identification method and of the control algorithm is highlighted in simulation environment.