Controller Design of Digital Hydraulic Flow Control Valve (original) (raw)
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Estimation of the potential in predictive control in a hybrid wheel loader
2009
In this paper the potential of predictive control in a hybrid wheel loader is estimated using related research results as a basis. The application of hybrid technology to a wheel loader application is discussed and differences between on-road vehicles and wheel loaders are clarified. The main part of the related research has its focus on on-road vehicles where the usage patterns are more coherent to a greater extent than for a wheel loader. The challenge with the design of hybrid technology for a wheel loader lies in the large variety of applications, ranging from more or less standardized loading cycles to material handling and transportation of goods. It is stated that a wheel loader during transportation is close to a typical on-road application. A line of arguments is presented which conclude that it should be possible to reach up to around 10% fuel savings using predictive control in a real wheel loader in a real application. However, much work remains to be done, for example on cycle definitions, high-level and low-level predictive controllers, and signal analysis before this point is reached.
Predictive control of a diesel electric wheel loader powertrain
Control Engineering Practice, 2015
Wheel loaders often have a highly repetitive pattern of operation, which can be used for creating a rough prediction of future operation. As the present torque converter based transmission is replaced with an infinitely variable device, such as an electric or hydraulic transmission, a freedom in the choice of engine speed is introduced. This choice is far from trivial in the extremely transient operation of these machines, but the availability of a load prediction should be utilized. In this paper, a predictive engine and generator controller, based on stochastic dynamic programming, is described, implemented and evaluated. The evaluation is performed against non-predictive controllers in the same system, to lift out any possible benefits of utilizing the repetition based prediction. Simulations and field tests show that the controllers are able to handle disturbances introduced from model errors, the machine environment and the human operator, and that the predictive controller gives around 5% lower fuel consumption than the non-predictive reference controllers.
Optimizing the trajectory of a wheel loader working in short loading cycles
Proceedings from the 13th Scandinavian International Conference on Fluid Power, June 3-5, 2013, Linköping, Sweden, 2013
A study into alternative trajectories for wheel loaders working in short loading cycles has been conducted, examining other patterns than the traditional V-or Y-cycle. Depending on workplace setup and target function of the optimisation other trajectories can indeed prove beneficial. The results of this study can be used in operator models for offline simulations as well as for operator assistance or even in controllers for autonomous machines or energy management systems for non-conventional machines like hybrids.
Mechatronics, 1998
The earth moving equipment industry is quickly gearing up to achieve great gains in e.ciency\ performance\ safety\ and operator comfort by the rapid deployment of recent digital control technology in its products[ There are two major types of earth moving equipment operating in large numbers] excavators and wheel type loaders[ Excavators have received much attention by the industry recently[ The wheel type loader product studied in this paper is another example of a high volume versatile machine at the opposite end of the con_guration spectrum[ A state of the art electro!hydraulic open centered non!pressure compensated valve control system is studied to evaluate the potential gains by implementing digital velocity servo control[ The control objectives are to "0# meet operator perceived response requirements\ "1# meet operator perceived smoothness requirements\ "2# create a sub!system that could accept commands from an autonomous high level planning controller[ Closed loop digital velocity control is successfully implemented in the racking motion of a wheel loader using a standard proportional!integral "PI# and a dynamic valve transform algorithm[ The dynamic valve transform is a function of hydraulic~ow rate which is a function of engine speed and rod end cylinder pressure[ Robustness of performance was veri_ed through extensive system modeling\ validation\ and hardware tests on a large Caterpillar wheel loader model 889[ Þ 0887 Published by Elsevier Science Ltd[ All rights reserved[
Fuel and time minimization in a CVT wheel loader application
IFAC Proceedings Volumes, 2013
A method is developed for the minimization of time and fuel required for performing a short loading cycle with a CVT wheel loader. A factor β is used for weighing time to fuel in the optimization. Dynamic programming is used as optimization algorithm, and the developed method is based on the change of independent variable, from time to distance driven. It is shown that a change of states from speeds to kinetic energies in the internal simulations is essential. A driving cycle, derived from measurements, representing a short loading cycle is introduced. Optimization is performed against this cycle according to the method presented, using two different values on the time to fuel weighing parameter. It is shown that this parameter can be used to find optimal solutions directed toward short time or low fuel consumption.
On Increasing Fuel Efficiency by Operator Assistant Systems in a Wheel Loader
The main focus of this paper is to estimate the potential increase in fuel efficiency and productivity by means of an operator assistant system, in a wheel loader working in a bucket application in a production chain. This is done based on an empirical study. A line of argument is presented on how to go from the empirical study to theoretical optimal control of a wheel loader. A suggestion of the human-machine-interaction is also presented. Fuel efficiency (ton/l) increases of 20-40% and productivity (ton/h) increases of 40-80 % are expected.
IJERT-Design and Development of Automatic Weighing System for Wheel Loader
International Journal of Engineering Research and Technology (IJERT), 2014
https://www.ijert.org/design-and-development-of-automatic-weighing-system-for-wheel-loader https://www.ijert.org/research/design-and-development-of-automatic-weighing-system-for-wheel-loader-IJERTV3IS111269.pdf A loader is a type of tractor used to scoop up loose material from the ground. The relationship between height of bucket and pressure in lift cylinder developed with the help of electronic data acquisition (EDAC) system for study and used in development of automatic on-board weighing system device. A hydro tech data logger is an electronic device that records data over time. On Board Weighing System for wheel loaders consists of a very high capacity pressure sensor fixed to the inlet port of the vehicle's lifting cylinder. The hydraulic pressure in the lifting cylinder is proportional to the load carried in the bucket. Static performance trials on the pressure sensor showed accuracy of linearity between dead load and output pressure. Trials conducted on new developed weighing system and pressure readings collected. Based on the obtained results, it is recommended that the developed weighing system should be incorporated on the wheel loader. The dissertation work is limited to develop automatic weighing system for wheel loader machines.
Kinematic Analysis and Optimization of a Wheel Loader Mechanism
Manufacturing Technology
The paper deals with kinematic analysis and dimensional optimization of a wheel loader mechanism. The kinematic analysis is based on the kinematic constraints of all joints in the mechanism. The objective function expresses the average angular displacement of the loader bucket and the optimization process leads to its minimum value. The wheel loader mechanism contains two hydraulic drives. The first drive is ensuring rotation of the boom (lifting the bucket) and the other rotation of the bucket. Optimization of the geometric dimensions of the wheel loader mechanism links gives their optimum values which ensure lifting the bucket with its negligible angular displacement carried out by just one hydraulic drive for rotation of the boom. The other hydraulic drive ensuring rotation of the bucket is stopped during lifting the bucket. The optimization results confirmed the possibility of lifting the bucket with just one hydraulic drive for rotation of the boom.