Application of actuator dynamics inversion techniques to active vibration control systems and shake table testing

• Autores: José Luis Ramírez Senent
• Directores de la Tesis: Iván Muñoz Díaz (dir. tes.), Jaime Higinio García Palacios (codir. tes.)
• Lectura: En la Universidad Politécnica de Madrid ( España ) en 2024
• Idioma: inglés
• Tribunal Calificador de la Tesis: Amadeo Benavent Climent (presid.), Javier Fernando Jiménez Alonso (secret.), Emiliano Pereira González (voc.), Leandro Moisés Morillas Romero (voc.), Antolín Lorenzana Ibán (voc.)
• Programa de doctorado: Programa Oficial de Doctorado en Ingeniería de Estructuras, Cimentaciones y Materiales
• Calificación: Sobresaliente Cum Laude
• Materias:
  • Física
    • Acústica
      • Vibraciones
    • Mecánica
      • Mecánica de medios continuos
  • Ciencias tecnológicas
    • Tecnología de la instrumentación
      • Ingeniería de control
• Enlaces
  • Tesis en acceso abierto en: Archivo Digital UPM
• Resumen

  • Excessive vibrations problems usually arise in lightweight structures subjected to human actions. The active vibration absorber constitutes an effective solution to mitigate these issues. Nevertheless, the dynamics of the actuators employed in such devices may play a detrimental role on the overall system performance and stability. Furthermore, the commissioning stage usually entails an intricated tuning process; consequently, adequate laboratory testing techniques would imply significant cost savings. Real-time hybrid simulation setups with integrated shake tables represent an efficient testing means for vibration absorbers. Unfortunately, shake tables are usually driven by hydraulic actuators which feature a marked non-linear behavior, with the consequent control associated difficulties. To make matters worse, the usage of the standard control approach is seriously hindered due to its iterative nature and inability to tackle references which change during the test. Control techniques able to compensate actuator dynamics in real time would be undoubtedly useful for their application in the previous control problems. Thus, this work focuses on the development of actuator dynamics inversion schemes for active vibration absorbers and hydraulic shake tables. Dynamic inversion techniques have been applied to the force control of electromagnetic proof-mass actuators employed in active vibration absorbers. The devised scheme has been incorporated into the well-known Direct Velocity Feedback scheme, leading to the Velocity Feedback with Dynamics Inversion algorithm. Additionally, the novel Broadband Force Cancellation algorithm has been proposed with an aim to mitigate vibrations in a wide frequency range, through a process of external forces estimation and cancellation. These inversion techniques may also be used to enhance the performance of any force-based control algorithm. The suggested methods have been assessed via numerical and experimental tests carried over a lightweight composite material footbridge. The results show that a significant force tracking improvement is attained. The Velocity Feedback with Dynamics Inversion algorithm clearly outperforms the classical scheme and shows potential for an even better comparative performance in structures with lower resonant frequencies, closer to that of the actuator. The Broadband Force Cancellation algorithm outcomes are better at high frequencies than those obtained with the velocity feedback schemes. Moreover, the application of dynamics inversion to the motion control of servohydraulic uniaxial shake tables has led to two novel control methods which have been numerically assessed. The first method allows for the application on the actuator piston of an arbitrary pressure force time derivative, which is calculated through a system impedance function identification procedure. The performance of this algorithm is considerably better than that of the iterative approach, since the hydraulics related non-linearities are approximately cancelled; however, a system identification is required, and it is not suitable for hybrid simulation, being more indicated for the upgradation of already existing control systems. The second method is based on the inversion of a linear state space model of the servoactuator driving the table. The model inputs are the control command and the force exerted on the actuator rod by the table assembly and its output is the rod acceleration. A notable acceleration tracking is achieved regardless of the specimen under test, greatly improving the iterative algorithm performance. The proposed method does not require iterations, is independent of the payload behavior and is able to reproduce references which change during the test, thus resulting promising for its application to hybrid simulation. This is possible, since all the relevant information from the moving mass dynamics is included in the force input, therefore allowing for its compensation.