A Quasi-Actual Mechatronic Instrument for Realistically Testing Roller-Piston Friction Pairs

Cam-lobe radical-piston hydraulic motors can achieve ultrahigh power rotary output (up to megawatts), which are widely used in tunnel boring machines, dredgers, and other high-end equipment. In these applications, hydraulic motors always operate in complex and drastically changing conditions, causing their key roller-piston friction pairs to be vulnerable to wear and failure. However, there is a lack of easy-to-use and low-cost testing instruments to investigate the failure behavior of friction pairs and verify the reliability of the developed friction pairs. For that, this study developed a quasi-actual mechatronic instrument that can realistically reproduce various actual operating conditions to achieve quasi-actual testing of the friction pair. This instrument is composed of three parts: a testing bench, a hydraulic system, and a control system. The hydraulic system with a proportional relief valve is responsible for adjusting the hydraulic pressure on the piston in the testing bench, while the roller speed is controlled by a servo motor in the testing bench. To realize the quasi-actual control, an improved fuzzy PID and PI control algorithms embedded in the control system are proposed to real-time regulate the hydraulic pressure and roller speed, respectively. Finally, several quasi-actual testing experiments are conducted to reproduce different operating conditions of roller-piston friction pairs in a tunnel boring machine. The experimental results show that quasi-actual hydraulic pressures and roller speeds obtained from the developed mechatronic instrument are in good agreement with the actual operating data from the tunnel boring machine, indicating that the mechatronic instrument offers a feasible, easy-to-use, and quasi-actual way for testing roller-piston friction pairs.