Parameterized State Feedback Control Applied to the 1st Degree of Freedom of a Cylindric Pneumatic Robot Marcos G. Q. Rijo 1(B ) , Eduardo A. Perondi 2 , Mário R. Sobczyk S. 2 , and Carlos A. C. Sarmanho Jr. 3 1 IFSUL Federal Institute, Sapiranga, RS, Brazil mqrijo@gmail.com 2 Mechanical Engineering Department, UFRGS University, Porto Alegre, RS, Brazil 3 IFSUL Federal Institute, Charqueadas, RS, Brazil Abstract. This paper addresses a gain-schedule trajectory controller applied to the first degree of freedom of a pneumatic five-degree cylindrical robot. The pro- posed control law is based on pole placement and state feedback techniques asso- ciated with a continuous gain-schedule scheme. Its gains are parameterized with respect to the trajectory-dependent mass moment of inertia of the manipulator with relation to its rotation axis. Therefore, the value of the equivalent transla- tional inertia to be moved by the first degree of freedom actuator is calculated on line and used to update the gain set of the controller. As consequence, the poles of the closed-loop system remain unaltered, which results in small per- formance losses due to payload variations. Performance enhancement is verified by means of experimental results of position trajectory errors for the controlled system considering invariant and variable equivalent mass applied to the 1 st DOF. Keywords: Gain-schedule control · State feedback control · Pneumatic robotic manipulator 1 Introduction Robotic manipulators are driven by electric motors or, less frequently, fluidic ones, according to several performance requirements such as precision, power/weight and power/volume ratios, maintainability, compliance, robustness, durability, reliability, response time, ease to control, energy source availability, energetic efficiency and cost. In this context, pneumatic actuators are attractive because they are fast, low-cost, easy to install (compressed air is common in industrial facilities), and durable, while present- ing high power/volume and power/weight ratios. Moreover, air compressibility is useful in collaborative applications since it facilitates handling fragile objects and interacting with humans, thereby enhancing overall compliance. Nevertheless, these actuators are difficult to control accurately for a number of reasons associated with highly nonlinear phenomena such as air compressibility, pressure dynamics in the chambers, dead zones in the control valves, and dry friction [1, 2]. Thus, significant effort has been spent © The Author(s), under exclusive license to Springer Nature Switzerland AG 2022 J. Machado et al. (Eds.): icieng 2021, LNME, pp. 25–36, 2022. https://doi.org/10.1007/978-3-030-79168-1_3