Tatiana Minav

Efficiency of Direct Driven Hydraulic Drive for Non-Road Mobile Working Machines

As answer for tendencies for compact and powerful solution for electro-hydraulic systems, this paper investigates directly driven hydraulic setup for non-road mobile machinery (NRMM) application. The control of the system is implemented directly with a servo motor drive without conventional hydraulic control valves, which allows accurate control and regeneration. Speed of the double-acting cylinder is determined by in-coming oil flow from the pump, out-coming flow to the hydraulic motor and angular speed of the electric motor. The paper provides a detailed analysis of the system and an evaluation of setup usage for NRMM application. Finally, possible improvements of the suggested system are discussed.

Towards a better energy efficiency through a systems approach in an industrial forklift system

The purpose of this study is to improve the potential energy recovery to electric energy in an electrohydraulic forklift system. The initial result achieved for the energy saving ratio after structural optimization is 40%. Component optimization is applied to the tested drive; this consists of an electric servomotor with direct torque control which is directly running a reversible hydraulic pump. According to the study, the energy efficiency and the energy recovery from the electrohydraulic forklift system can be increased by 11%. New ideas and directions for further research were obtained during the study.

Self-tuning parameter fuzzy PID controller for autonomous differential drive mobile robot

The purpose of this study is to utilize the capabilities of a fuzzy PID controller for electric drives for a differential drive autonomous mobile robot trajectory application. The robot is powered by two non-identical electric motors. A self-tuning-parameter fuzzy PID controller is designed to control the rotation speed of the motors independently in order to achieve a straight trajectory of the motion despite the motor differences. Simulation of the robot drive system is carried out in a Matlab/Simulink environment. Simulations were used to evaluate performance of the fuzzy self-tuning parameter PID controllers in the time domain. Conclusions are drawn concerning the performance of the controller. Furthermore, expected challenges for the future development are discussed.

Control system of unmanned aerial vehicle

In this paper, the quadrotor ESC-motor-propeller subsystem identified and computer model design for the quadrotor fuzzy logic control system is developed. Two controllers based on Fuzzy logic and PID were presented and examined with respect to their best performance. The conducted analysis proved the ability of the designed fuzzy logic controller in controlling the orientation platform angles and providing the promising fundamentals for practical experiments. The presented solution can be applied in both an indoor and outdoor environment. Furthermore, expected challenges for the future are discussed.

Direct Driven Hydraulics: What can possibly go wrong? -A thermal analysis

This paper focuses on a thermal analysis of Direct Driven Hydraulics (DDH). DDH combines the benefits of electric and hydraulic technologies in a compact package with high power density, superior performance and increased controllability. It enables a reduction of hydraulic losses therefore achieves better fuel efficiency. The main advantages of the presented architecture compared to a conventional valve-controlled system are the reduced hydraulic tubing and the amount of potential leakage points. DDH however represents a challenge for the prediction of the thermal behavior and its management as the temperature is a determining parameter of performance, lifespan, and safety of the system. Therefore, the electro-hydraulic model of a DDH involving a variable motor speed, two fixed-displacement internal gear pump/motors was developed at a system level for thermal analysis. In addition, losses dependent on temperature were validated by measurements under various operating conditions set by a cold chamber to 20, 10, and -5 °C. A model investigation predict heat dissipation from the electrical machine to the rest of the system. The electric machine heat dissipation plays an important role in the system temperature balance while the DDH is operated in extreme continuous operating condition. Furthermore, expected challenges for the future development of DDH concept are discussed.

POSITION CONTROL OF DIRECT DRIVEN HYDRAULIC DRIVE

This paper investigates directly driven hydraulic setup for non-road mobile machinery (NRMM) application. The purpose of this research is to utilize the excellent control capabilities of modern electric drives in electro-hydraulic systems, create direct drive position control for the hydraulic cylinder and verify the results by measurements. The control is implemented directly with a motor drive without conventional control valves. Speed and position of the double-acting cylinder is determined by in-coming oil flow from the pump, out-coming flow of hydraulic motor and angular speed of the electric motor with a single feedback from motor rotor encoder. Empirical results proved that the control suits NRMM application. The achieved maximum final position error of 3.1 % of the position control for tested cycle is fulfilling required accuracy.Copyright

Adaptive Control for Direct-Driven Hydraulic Drive

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Fuzzy control of direct-driven hydraulic drive without conventional oil tank

The direct-driven hydraulic drive (DDH) combines the advantages of compact high power of the hydraulic system and flexible control of the electric motor. This paper concentrates on modelling of the direct-driven hydraulic setup and investigating control challenges. In the DDH setup, the speed and position control of a double-acting cylinder is implemented directly with a Synchronous Torque Motor drive in a close-loop system without conventional valve-control. In addition to this, hydraulic accumulator is employed as a replacement of the conventional oil tank. To achieve excellent control capabilities, a fuzzy controller is designed to control the rotation speed of the motor drive. The system is investigated by means of simulations. As a result, designed controller benefits the hydraulic system.

A control strategy for an autonomous differential drive mobile robot

The purpose of this research is to develop a control strategy for a differential drive autonomous mobile robot. The robotic task is to move in a straight trajectory in the workspace despite powered by two non-identical electric motors. A developed controller was designed to control the rotational speed of the motors independently in order to achieve a straight trajectory of the motion despite the motor differences. In order to fulfil control limitations, a trajectory control strategy with an inertial measurement unit (IMU) is proposed. This leads to the creation of a Matlab/Simulink model of the robot drive system and IMU, which takes into consideration the mechanical constraints of the robot. In this study, simulations were utilized to evaluate performance of the developed controller in the time domain. The usefulness and effectiveness of the developed control strategy is confirmed by simulation. Simulation results demonstrated that the speeds of the motors can be matched quite well, and difference between the achieved and a straight-line trajectory was within a few centimeters. Furthermore, expected challenges are discussed for the future development.

Electric-driven Zonal Hydraulics in Non-Road Mobile Machinery

The goal of this research is to apply direct-driven hydraulics (DDH) to the concept of zo‐ nal (i.e., locally and operation-focused) hydraulics, which is an essential step in the hy‐ bridization and automation of machines. DDH itself aims to combine the best properties of electric and hydraulic technologies and will lead to increased productivity, minimized energy consumption and higher robust performance in both stationary and mobile ma‐ chines operating in various environments. In the proposed setup, the speed and position control of a double-acting cylinder is implemented directly with an electric motor drive in a closed-loop system without conventional control valves and an oil tank. The selection of the location of the hydraulic accumulator and connection of the external leakage lines will also be part of this study. Simulations and experimental research to study the details of the hydromechanical and electrical realization of the DDH are performed.