PI Controller for IPMC Actuators Based on Nafion (R)/PT Using Machine Vision for Feedback at Different Relative Humidities

Author(s)

Zuquello, Ariel Gustavo ; Saccardo, Matheus Colovati ; Goncalves, Roger ; Tozzi, Kaique Afonso ; Barbosa, Rafael ; Hirano, Laos Alexandre ; Scuracchio, Carlos Henrique

• Document type: Journal article
• Source: MATERIALS RESEARCH-IBERO-AMERICAN JOURNAL OF MATERIALS; v. 25, p. 12-pg., 2022-01-01.

Abstract

Ionomeric Polymer-Metal Composites (IPMCs) are sandwich-like materials based in a polymeric membrane covered on both sides by metallic electrodes. Its operation mechanism consists of hydrated ions migration in response to an external electrical field generated between the electrodes, leading to a spatially nonuniform mass accumulation which causes the device to bend. Its performance as an actuator depends mainly on the environment's relative humidity and electrical stimuli. Consequently, IPMCs present variations in the electromechanical properties exhibiting nonlinearities and time-varying behaviors, limiting the major applications. For this reason, this paper investigated a PI controller performance to overcome these drawbacks and effectively control a Nafion-based IPMC-Li+ exposed to different relative humidities and electrical stimulis. The PI control system uses a camera with a machine vision application as a feedback sensor. Support instrumentation was developed to control the relative humidity, apply an electrical stimulus, and measure the electromechanical response. The pattern recognition algorithm implemented in the controller is efficient, with accuracy above 95%, making the feedback sensor reliable. Therefore, the PI controller was effective, stable, and capable of controlling and characterizing IPMC devices when relative humidity was above 60% at a low-frequency displacement and avoided the undesired back-relaxation phenomenon. (AU)

• FAPESP's process: 18/09761-8 - Study and development of ionic polymer/metal composites for application in actuators and sensors aiming low cost and high performance
• Grantee: Roger Gonçalves
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 20/02696-6 - Synthesis and characterization of artificial muscles based on SBS block copolymers with selective sulfonation of the phases
• Grantee: Matheus Colovati Saccardo
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 18/07001-6 - Study and characterization of ionic conductive polymers used as artificial muscles: proposals for performance improvement
• Grantee: Carlos Henrique Scuracchio
• Support Opportunities: Regular Research Grants
• FAPESP's process: 18/10843-9 - Study of deformation behavior of artificial muscles based on electroactive polymers: performance enhancement proposal
• Grantee: Matheus Colovati Saccardo
• Support Opportunities: Scholarships in Brazil - Master