Browsing by Author "Sourander, Tom"

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Control strategy for a direct driven hydraulics system in the case of a mining loader
(2018) Martinovski, Tatjana; Sourander, Tom; Turunen, Aleksi; Minav, Tatiana; Pietola, Matti
A4 Artikkeli konferenssijulkaisussa
As a response to the strict government emissions regulations, hybridisation of non-road mobile machinery is required. In this paper, behaviour and efficiency of a hybrid mining loader is studied. The full prototype with implemented DDH (Direct Driven Hydraulics) units had been built; however, its performance was unsatisfactory – a large undershoot and steady-state error of 34 % persisted. Therefore, a new control strategy was suggested to overcome the issues. Performance of the system was enhanced by applying a fuzzy PID controller. As a result, reference tracking was significantly improved compared to the conventional PID control case and steady-state error of 1 % was achieved, while the overall efficiency was kept high in the range of above 50%.
Kaupunkibussien kevytrakennetekniikka
(2013-04-23) Sourander, Tom
Insinööritieteiden korkeakoulu | Bachelor's thesis
Sensorless position control of direct driven hydraulic actuators
(2017-09-25) Sourander, Tom
Insinööritieteiden korkeakoulu | Master's thesis
This thesis investigates sensorless position control of valveless pump-controlled hydraulic actuators for non-road mobile machinery (NRMM). The utilized hydraulic systems are direct driven hydraulics (DDH), a type of electrohydrostatic actuators (EHA), which uses an electric servomotor to drive hydraulic pumps of a single hydraulic cylinder or parallel cylinder group. The advantages of DDH over traditional valve-controlled hydraulics are increased energy efficiency due to elimination of the valve losses and improved controllability due to no need for servovalves. Advantages and disadvantages of various types of position sensors, which are available on the market were investigated for hydraulic cylinder application. These sensors, while accurate, have been noted to be rather expensive and not suitable for harsh environment applications. Virtual sensors can provide an alternative to physical position sensors. The servomotor driven pumps provides a possibility for sensorless position control of hydraulic cylinders without need for sensors. The sensorless position control was realized by simulating the interaction of DDH units and hydraulic cylinders of a testbed prototype hybrid mining loader. By utilizing only torque and speed data received from electric motor controller it is possible to simulate the position of a cylinder, provided that all relevant parameters such as pump and cylinder dimensions and efficiencies as well as oil properties are known. Simulation model of the DDH system of the mining loader was realized using Matlab/Simulink Simscape hydraulic and multibody blocks. Results within the simulation showed that the model can reach an accuracy within a few millimetres for a single cycle. The maximum error increased with increasing load and a cumulative error for repeated cycles was observed, which recommends simple cylinder end or middle point proximity sensors to be used as reference points. Measured data from a test work cycle with no load and with 1040 and 2205 kg loads were used to test the accuracy of the simulation. Results demonstrated that the maximum error increased with increasing load as in the simulation. The errors were reduced by utilizing the reference points, especially during successive cycles. Tests using the position calculation as sensors demonstrated slightly higher error. However it verified that it is possible to be utilized as a virtual position sensor for cylinder movement control with centimetre scale accuracy when assisted by error compensation methods.
Sensorless position estimation of simulated direct driven hydraulic actuators
(2017-06-07) Sourander, Tom; Pietola, Matti; Minav, Tatiana; Hänninen, Henri
A4 Artikkeli konferenssijulkaisussa
This study researched method for achieving sensorless position control of hydraulic cylinders driven by direct driven hydraulic units. Direct driven hydraulics is a pump controlled hydraulic system that uses an electric motor driven pumps to drive a single actuator, which brings energy saving and controllability advantages to traditional valve controlled hydraulics. Advantages and disadvantages of various types of hydraulic cylinder position sensors were investigated. These sensors, while accurate, have been noted to be rather expensive and some types have been problematic to implement in some harsh environment applications. Virtual sensors can provide an alternative to physical position sensors. Using only torque and speed data received from electric pump motor controller it is possible to simulate the position of a cylinder provided that all relevant parameters are known. A Sandvik EJC90 mining loader, fitted with diesel electric hybrid drivetrain and direct driven hydraulic units for bucket and boom actuation, was used as a test platform. The hydraulic systems were instrumented with pressure, temperature and cylinder position sensors for research purposes. Simulation of the direct driven hydraulic system was done using Matlab Simulink Simscape hydraulics blocks. Parameters for components were gathered from manufacturer datasheets and those not available are to be measured from the real system. Simulated results of cylinder movement at a motor torque and speed level will be compared to measurements made with the real systems. Preliminary results within the simulation show that the model can reach an accuracy within a few millimeters for a single cycle. A cumulative error for repeated cycles was observed, which recommends simple cylinder end or middle point proximity sensors to be used as reference points.