Researchers from Japan and Vietnam have introduced an innovative approach to control pneumatic artificial muscle (PAM) systems. As PAMs increasingly mimic human-like movements, finding accurate control mechanisms has become paramount for applications in industries such as robotics, rehabilitation, and prosthetics.
The mechanics of PAMs, typically made of rubber and braided yarn, allows them to stiffen and contract when filled with pressurized air. Conversely, they soften and extend upon releasing the air. This system’s inherent nonlinearity has posed significant challenges for control, especially given the latency PAMs can experience.
Traditional control methods, while effective to an extent, fall short in accommodating PAM’s nonlinearity and hysteresis. Aspiring to address this gap, Associate Professor Ngoc-Tam BUI of Shibaura Institute of Technology in Japan and Dr. Quy-Thinh Dao of Hanoi University of Science and Technology, unveiled an “adaptive fuzzy sliding mode controller (AFSMC)” in a recent publication. This groundbreaking approach employs fuzzy logic for estimating control parameters of PAM systems.
The duo’s methodology harnesses the Takagi–Sugeno fuzzy algorithm, marking a significant leap from conventional sliding mode control methods. “Our adaptive fuzzy algorithm autonomously updates parameter vectors, resulting in enhanced tracking accuracy and adaptability,” states Associate Professor BUI.
In their experimental phase, the AFSMC displayed impressive results. Compared to traditional methods, the AFSMC reported superior tracking accuracy and was notably adept in adjusting to sudden external disturbances. “When measured against the established LOKOMAT rehabilitation system, our controller showcased comparable performance. Its capacity to swiftly recalibrate following unexpected load changes was particularly remarkable,” elaborated Associate Professor BUI.
The AFSMC’s prowess signifies a promising avenue for its integration into robotic rehabilitation equipment, assistive devices, and advanced prosthetic limbs. These applications are poised to revolutionize personal therapy, enabling greater precision and customization for patients.
Looking ahead, Associate Professor BUI is optimistic: “Given our research’s outcomes, I anticipate the commercial release of a PAM-actuated rehabilitation system within the next decade. Such an innovation will be transformative for patients, especially those recovering from spinal cord injuries, strokes, or other conditions necessitating rehabilitation.”
Photo: credit Ngoc-Tam BUI from SIT, Japan