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The heavy earth moving machineries (HEMM) like hydraulic excavator play a major role in construction and mining industries. In this context, the energy saving strategies in hydraulic excavator needs to be addressed considering its vital importance. Since the hydraulic excavators are subjected to heavy loads, hence the opportunity to harness the potential gravitational energy (GPE) remains a key area which can be effectively explored in order to minimize the energy consumption in consideration with hydraulic excavator. In the projected system, the potential energy is stored as pressure energy in hydro-pneumatic accumulator. The upward movement of the boom is executed with the help of prime mover during the starting of the first duty cycle. In the latter duty cycles, the stored pressurized energy is utilized together with the prime mover energy capable to execute the upward movement of the boom. The position of the boom cylinder is controlled by using the conventional PID controller using proportional flow control valve (PFCV) and accumulator. The error between the actual position and demand position of the linear actuator is minimized along with attainment of superior controlled performance while utilizing Model Predictive Controller (MPC). The pressurized accumulator with PFCV has been utilized to cater the different position demands. This has been also justified both experimentally and analytically with the error in the permissible range of 2%. It has been observed that the proposed system is 10% more efficient in contrast to the conventional system.

Digital Displacement Machines (DDM) have been shown to improve energy efficiency for various applications such as wind turbine and automotive transmission systems. A DDM’s performance depends heavily on the digital valves that it utilizes. This paper investigates the required digital valve flow coefficient and switching time for realizing a digital offshore winch drive. The proposed drive improves system efficiency and reliability by replacing the winch’s conventional hydraulic motors with DDMs and removing the gearboxes. A commercially available winch system of an offshore knuckle-boom crane is used as an example when deriving the parameters of the DDM. The valve specifications are derived conservatively based on simulations to ensure a motor efficiency of at least 90 % throughout the operating range of the winch. A partial-stroke strategy is used to control the motor displacement where the highpressure valve can be closed at any given shaft angle before the cylinder reaches the top dead center. It is concluded that commercially available valves will require a DDM with a high number of cylinders, resulting in a complex system with high cost. On the contrary, certain prototype valves have shown promise for enabling the use of DDM with as few as seven pistons. However, further experimental work is required to verify the performance of these valves.

This paper highlights development of 2-DOF and 3-DOF energy management controllers using a Machine Learning (ML) algorithm for closed-circuit hydrostatic transmission of Front-End Loader (FEL) machine. Objective of energy management controller, is to keep prime-mover, pump and hydro-motor in its efficient zone irrespective of variation of load-speed at drive end. Based on duty cycles of the transmission and sensitivity analysis of drive components, GPR algorithm shows better prediction (within 3%) of optimized commands of hydro-motor and pump displacements and their operating speeds, which results in its efficient operation. Validated model of hydraulic transmission components is integrated with verified model of IC engine to investigate saving in fuel consumption through designed controllers. Comparative study between 2-DOF and 3-DOF controlled transmission systems infers that fuel consumption for engine in 3-DOF controlled system decreases up to 34% of that of 2-DOF with a 20%–30% relative increase in overall drive efficiency.

The role of hydraulic systems is quite evident especially in the case of heavy machineries employed in industries, where the utilisation of high forces amid large stiffness is the prerequisite. Nevertheless, there has been substantial effort put forward in the development of advanced control strategies which finally addressed the issue of the position control. Proportional–integral–derivative control strategy happens to be one among them, which is a versatile and widely renowned approach involved in the position control in this study. Although, it is quite frequently observed that the hydraulic actuation system possesses strong nonlinearities. In this article, two different actuator position control strategies, that is, swash plate control of main pump and speed control strategy of prime mover are compared. In swash plate control strategy, the proportional–integral–derivative controller adjusts the swash plate of main pump through servo mechanism, whereas in the speed control strategy, the proportional–integral–derivative controller adjusts the speed of the electric motor through variable-frequency drive. For this purpose, two MATLAB-Simulink models are developed and validated experimentally. It is found that swash plate control strategy has better dynamic and control performance than the speed control strategy catering same position demand of the linear actuator.

Hydrostatic transmission (HST) system is widely used in the Heavy Earth Moving Machineries (HEMM). The hydro-motor used in the HST system provides the rotary motion for their traction, swing or other functions used in HEMM catering to different load profiles. This causes continuous variation in speed of the hydro-motor which reduces the efficiency of the HST system. Hence, controlling the speed of the hydro-motor is very much indeed. Constant speed of the hydro-motor can be achieved by controlling the input flow of it. Input flow can be controlled by controlling the displacement of the variable displacement hydraulic pump or by varying the flow through a proportional directional control valve (PDCV). The main objective of this research work is to design the PID controller which regulates the input flow to the hydro-motor so that the speed of the hydro-motor remains constant irrespective of the varying external load. To increase the PID controller performance, fuzzy control algorithm has been employed using MATLAB/Simulink environment. The main function of the fuzzy controller is to online tune the PID parameters which increase the performance of the drive. Comparison has been drawn based on the results obtained using Fuzzy-PID controller to the simple PID controller. The results show that Fuzzy tuned PID controller provides minimum settling time and less overshoot when compared to simple PID controller.

Considering the loss of high throttling loss for open-circuit hydrostatic transmission at present, hydraulic excavation energy saving is important for removing the source of deficiency and protecting the environment. This paper deals with closed circuit gravitational potential energy recovery system (GPERS) based on energy storage element such as an accumulator, along with the generator. An estimated 16% total energy consumption is reduced when a system using accumulator-motor-generator system is used as compared to the simple motor system. The simulation result is carried out with Automation Studio and MATLAB/Simulink. At last, the paper put forward the future development of GPERS.

The work presents a segmented pump-motor control scheme of a closed-loop hydraulic drive used in mining equipment. It analyses the dynamics of the drive through modeling and simulation. The system model integrates a control scheme for modulating the displacement of the pump and the hydro-motor of the hydraulic drive. The model also considers the state-dependent non-linear losses as well as the transient behaviors of the pump and the hydro-motor. The experimental results validate the model for various working conditions of the equipment. The model simulation also analyses the perturbation of critical parameters and control gain on the system's performance for a wide range of operating conditions of the mining equipment. The study performed in this research work will be expedient for the preliminary design and assortment of similar hydraulic drive used in the mobile equipment.

In this article, the focus is on the energy efficiency along with the position control of the linear actuator used in heavy earth moving equipment. It is quite evident that linear actuators are one of the critical machinery components used in the construction and mining activities like in booms of excavation equipment. The proposed work employed two different hydraulic circuits and a contrast has been carried out in terms of the energy efficiency. In one hydraulic circuit, the conventional proportional directional control valve (PDCV) is used for the position control. In another one, an innovative solution of using proportional flow control valve (PFCV) by creating artificial leakage between the two ends of the actuator is evaluated according to its energy efficiency. The extra flow coming from the pump during position control is by-passed by PFCV rather than the pressure relief valve in PDCV. This reduces the energy loss in the form of heat and increases the efficiency of the hydraulic circuit. The simulation of the hydraulic circuit is performed using MATLAB/Simulink and results are compared with the experiments and it is found that hydraulic circuit using PFCV is 8.5% more energy efficient than the conventional circuit using PDCV. The position control of the actuator is done using PID controller tuned by the fuzzy controller.

Counter balance valves are used in hydraulic systems to withhold the vertical loads by preventing the free flow of the hydraulic fluid for the safety purpose. But due to this safety feature of the valve, it creates back pressure on the actuator, when the actuation of the cylinder is required in upward direction, to lift the load. This increases the pressure losses across the actuator in the hydraulic system and in turn heat the oil unnecessarily. This, in turn, causes the system to be energy inefficient. But, in today’s competitive world development of energy efficient systems (EES) is an important aspect. In this article, comparison of energy efficient hydraulic system is done using Pilot Operated Counter Balance Valve (POCBV) and Conventional Counter Balance Valve (CCBV) through MATLAB®/Simulink environment. It has been found that POCBV is more energy efficient than CCBV for a particular set of operating conditions. Effects of physical parameters like pilot ratio, spring rate on stability and efficiency used in designing of POCBV are also studied and compared using MATLAB®/Simulink environment. This model is beneficial for hydraulic machine manufacturers engaged in designing of lifting devices in selecting a suitable valve for particular load application and for the designers to design the main components of the valve.

Blast hole drill machines are used for drilling in rocks, which are of soft and medium-hard nature. In such machines, the drilling is accomplished via a hydrostatic transmission (HST) drive. This article presents the steady-state behaviours of two different HST drives for the rotary head of drill machine. In the first drive two high-speed low-torque (HSLT) hydro-motors, having an individual capacity of 10 cc/rev with the gear reducer having 15:1 gear ratio; whereas in the second drive identical numbers of hydro-motors, having an individual capacity of 16 cc/rev with the gear reducer having 10:1 gear ratio is employed. Bond graph technique has been used for modelling the drives. Based on the model, the analytical relations associating the torque loss, slip, and the overall efficiency linked with the drives are derived. By utilizing them, the performance corresponding to the HST drives is obtained in terms of the normal operating speed range linked with the drill machine utilized in mining applications. From the study it is observed that, for the constant load torque and the drill speed, the second drive (combination of two identical higher size hydro-motors along with a lower size gear reducer unit) shows better performance than the first drive (combination of two identical lower size hydro-motors along with a higher size gear reducer unit).