Andreas Plöckinger, Christoph Gradl, Rudolf Scheidl,
"High Accuracy Sensorless Hydraulic Stepping Actuator"
, in Janne Uusi-Heikkilä & Matti Linjama: Proceedings of The Eight Workshop on Digital Fluid Power, May 24-25, 2016, Tampere, Finland, Tampere University of Technology - Department of Intelligent Hydraulics and Automation, Tampere, 5-2016
High Accuracy Sensorless Hydraulic Stepping Actuator
Sprache des Titels:
Proceedings of The Eight Workshop on Digital Fluid Power, May 24-25, 2016, Tampere, Finland
This paper presents a linear hydraulic stepper drive concept for accurate sensor-less positioning control in industry. The stepping actuator consists of a cylinder piston unit which displaces defined fluid quanta by a limited forward strokes of a piston. Each fluid quantum leads to a precise motion step. In a prior, more general concept the step size was influenced by the chamber pressure (load pressure) of the hydraulic cylinder. A mathematical model in combination with a pressure sensor was needed to compensate for these influences in order to achieve a high accuracy.
The present alternative concept uses a passive pressure regulator valve to achieve a nearly constant chamber pressure in order to avoid a pressure transducer and a computational model for position estimation. For concept evaluation, a test rig was built and experiments were performed to study the positioning accuracy, repeatability, linearity, and scattering range of the proposed stepper drive concept. Two different step sizes (5 µm and 15 µm) were tested and verified by measurements. In this paper just the results for 15 µm are depicted. The results show the high accuracy of the hydraulic stepping actuator.
The practical relevance of the drive concept is proven by an application example, comprising a sensor-less control against a spring load. The experimental testing was done by hardware in the loop simulation, where the computed spring force is imposed to the physical stepper drive via a controlled hydraulic force.
Sprache der Kurzfassung:
Tampere University of Technology - Department of Intelligent Hydraulics and Automation