Force control benchmarking of hydraulic and electrical actuation systems applied to robotics

• Ano de defesa: 2024
• Autor(a) principal: Vergamini, Elisa Gamper
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: benchmarking; atuadores elétricos e hidráulicos; controle de força; electric and hydraulic actuators; force control; interação física; physical interaction
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/18/18162/tde-11062024-113219/

Designers have faced difficulties when it comes to the interaction between robots and humans in dynamic environments. Managing the events in such scenarios involves controlling the force and velocity of the robots. There are two approaches to achieve this: controlling only the force or indirectly controlling the relationship between force and velocity through impedance. In addition to these factors, researchers have also investigated controllers for collaborative robots, legged robots and exoskeletons. This has posed a challenge for designers in determining the appropriate drive system to use. To address this issue, it is beneficial to provide a comprehensive comparison of controller-actuator combinations, which can serve as a guide for selecting the most suitable elements based on the specific application. Hence, the objective of this master\'s project is to systematically compare the stability and performance of force controllers in electric and hydraulic actuators. In order to achieve this goal, an experimental setup was designed, constructed and validated, along with the development of a benchmarking methodology that includes a range of metrics to assess performance, passivity, and stability. The methodology is applicable to all types of actuators and force controllers. Its approach enables the calculation of metrics regardless of loads or environments. It was implemented on three distinct actuation systems: a DC motor, a linear electric motor (PMLSM), and a hydraulic actuator (servo valve and cylinder). Various controllers, including different variations of PIDs, load velocity compensation, and disturbance observers (DOB), were tested for each actuator. The metrics obtained from the tests provided insights into the influence of different control architectures on the performance and stability of the actuators. For instance, it was observed that the derivative gain negatively affected the linear electric motor, while load velocity compensations showed more enhancements for hydraulic actuators. Moreover, linear controllers like PID exhibited poorer performance in systems with higher levels of non-linearities, such as hydraulic systems. There are both advantages and disadvantages to using the systems identified in the methodology. On the positive side, these transfer functions allow for the inclusion of metrics that can provide a more comprehensive evaluation of the system stability. However, it is important to note that these metrics can be influenced by external variables such as friction and uncertainties in the experimental data used on the identification process. Additionally, the use of this method enabled faster calculation of metrics and the capture of the most important information regarding force control in the studied cases.