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Fluid-driven actuators are not only well-established in automation, but also a promising drive technology for collaborative robots. Their inherent compliance due to the compressibility of suitable fluids such as air, as well as their direct drive properties are advantageous safety features for human-machine collaboration. In this work, we provide an overview of different fluid-driven manipulators, namely fluidic muscle actuated ones, continuum manipulators, and those with rotary joints. For the latter, we introduce the mathematical model including mechanics and pressure dynamics and describe its properties such as strong nonlinearities, which make trajectory tracking control challenging. A model-based nonlinear cascaded controller is presented. Experimental results on a 6 degrees of freedom (DOF) prototype demonstrate the resulting trajectory tracking performance.

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As the public call for increasing efforts in achieving the global climate protection goals intensifies, discussions about the efficient use of resources and energy are on the daily agenda. As many other areas, the industry has seen itself facing growing concerns about the long neglected environmental aspects. Since a large proportion of the energy in production is used by pneumatic drives, this survey paper exclusively focuses on pneumatics in handling and automation technology and presents the most common components, followed by multiple model-based strategies to increase energy efficiency in modern production plants. First, single units are studied extensively and methods for design and energy efficient control are presented. Since in production lines pneumatic drives are generally operated in large networks, the second part focuses on energy efficient strategies at plant level. These include an optimized adjustment of the supply pressure, a cascaded air usage, and an automated adaptive control pattern. Care is taken to ensure that the considered approaches are applicable in today’s industrial plants, which is demonstrated by experiments in a production line. The experimental findings show the immense potential of the discussed measures in the form of compressed air savings of more than 60% compared to the industry standard.

Zusammenfassung Die physikalischen Eigenschaften pneumatischer Antriebe ermöglichen den Bau von sicheren, leichten und intuitiv bedienbaren Robotern, deren Regelung jedoch herausfordernd ist. Gründe dafür sind die Dynamik der Pneumatik und nichtlineare Reibung mit Unsicherheiten, die ohne abtriebsseitige Momentensensorik unbekannt ist. In dieser Arbeit wird die nichtlineare modellbasierte Trajektorienfolgeregelung eines Roboters mit sechs pneumatischen Drehgelenken vorgestellt. Sie umfasst die Mechanik und Pneumatik sowie, im Gegensatz zum Stand der Technik, deren Verkopplung in einem zentralen Regler. Ausgehend vom dynamischen Modell des Gesamtsystems wird der Regler mittels Feedback-Linearisierung, einem Sonderfall der differentiellen Flachheit, hergeleitet. Die Regelung wird experimentell validiert und anhand der Messungen werden praktische Auswirkungen ihrer Struktur aufgezeigt.