Engineering vehicle hydraulic chassis simulating experimental device is a large-scale, complicated, high-tech electromechanical
system, which is integration of many technologies such as control, test, mechanical design and manufacture, electric and hydraulic
technologies. This one is composed of four sections: simulating driving system, simulating loading system, control and test system,
auxiliary devices. The driving system can simulate centre driving mode, double-bridge four-wheel driving mode and wheel-side
independent driving mode, which are primary modes adopted by current engineering vehicle hydraulic chassis driving system. The
subject of engineering vehicle hydraulic chassis simulating experimental device has important meaning for research and development
of engineering vehicle.
Field bus and Industrial Fast Ethernet network technology are used in communication scheme of experimental device to set up
three layers network architecture to fulfill test, control and management functions. FCS, Pc-based control and HMI are connected
seamless and establish a safe, efficient, reliable and simple integrated automation platform.
The experimental device is based on field bus control system. So, the duration of message cycle has a important effect on performance
of control system. Against the uncertainty of message cycle time from frame retransmission, waiting and acyclic activity,
this dissertation give a detailed analytical description of the Profibus DP cycle time, taking into consideration the random variables
that make up it. The stochastic model of Profibus massage cycle time based on multiple masters is also given.
Using capacity control mode, one hydraulic displacement pump driving two hydraulic displacement motors to achieve speed synchronization
is multiple inputs multiple outputs system with coupling and nonlinear characters. In this dissertation, an uncoupling
control strategy, flow equilibrium and power match strategy, is proposed to reach the preset synchronous speed of motors even suffering
different loads. Experiment research was done and the control strategy was validated. Against this problem that loads disturb
speed severely, according to the characters of immune system restraining disturbance and stabilizing itself quickly, a kind of IMF
(Immune Feedback) controller is proposed in this dissertation. The simulation results illustrate that IMF controller can restrain the
disturbance from outside loads effectively while get a good speed synchronization performance.
A novel type hydraulic chassis technology, four wheels driving technologies independently, is proposed, which is based on secondary
regulation technology and an improved Narendra MRAC scheme. Simulation results illustrate that the improved adaptive
algorithm has good regulation performance against such disadvantages as modeling uncertainty of secondary unit, pressure fluctuation
of constant pressure network, and disturbance from load etc. Compared with the characteristics of such hydraulic chassis driving
technologies as one pump driving one motor, one pump driving two motors and double pumps driving double motors, this driving
system adopting the improved adaptive control algorithm has so many merits as simple driving mechanism, flexible driving mode, infinitely variable speeds, high efficiency, excellent road adaptability, easy control and so on. Meanwhile, dynamic performance and
energy saving of the driving system is also improved. This four-wheel independent drive scheme can meet the demands of high
speed, stability and off-road mobility from special type of vehicles.
Commercial variable-rate granular fertilizer applicator systems for citrus were modelled with various possible configurations of
the hydraulic and mechanical components. The gains, time constants, and transportation delays of the physical components, such as
flow control valves, hydraulic motor, and encoders, were modelled based upon experimental testing and control theory. PID control
algorithms were developed and evaluated based upon performance criteria developed for the specific problem of fertilizing individual
trees.
ITS(Intelligent Transport Systems) is a new transport system which is comprised of an advanced information and telecommunications
network for users, roads and vehicles. ITS contributes much to solving problems such as traffic accidents and congestions.
ASV(Advanced Safety Vehicle) is a prototype vehicle, and its main purposes are drivers safety, accident avoidance, mitigations and
so on.
This dissertation is concerned with a longitudinal control technique for heavy-duty vehicles, which is one of the key technologies
for ITS and ASV. As the first step of developing a series of techniques for speed control of automated driving of heavy-duty vehicles,
a new speed control algorithm for heavy-duty vehicles with constant acceleration/deceleration to keep smooth traffic flow is proposed.
The algorithm covers various driving situations such as start-up, constant acceleration/deceleration, variable acceleration/
deceleration and stop. Next, the control performance when applying this algorithm to the heavy-duty vehicles is investigated by
computer simulation and experiments. The validation of the proposed algorithm is proved.
In the simulation, the heavy-duty vehicles model is developed based on the experimental data. Because the brake system has a
great effect on safety-driving, simulation study is carried out to investigate the transient phenomena of the AOH(Air Over Hydraulic)
brake system, to evaluate the appropriateness of the simulation model, and to reveal the main factor which results in the transient
phenomena. Through the simulation, the main factor which results in transient phenomenon is made clear.
Modification of the control algorithm is also carried out considering transient characteristics in acceleration and deceleration. A
deceleration coefficient, which is defined as a ratio of deceleration of a vehicle to the pressure of the braking component, is measured
experimentally and applied to the control of vehicle speed. Using a test vehicle, speed control applying the online estimated deceleration
coefficient was also accomplished to improve the control performance and resultantly it has been demonstrated that the braking
process was precisely controlled.
With the developing of hydraulic technology, the demand for characteristic test of hydraulic system becomes higher and higher,
it has become important means of developing hydraulic technology and improving hydraulic component performance to highprecision
testing on hydraulic component. Hydraulic Computer Aided Test(CAT) is the application of computer aided test in hydraulic
system. In the process of test, computer can monitor the hydraulic system in response to the numeric feedback in order to fulfilling
high-precision and high speed characteristic test. The hydraulic pump CAT system in this paper is designed to aim at multi-types air
hydraulic pump. This paper shows detailed design for dive system, hydraulic system and test & control system. The test and control
system and the emulator program of hydraulic pump fault diagnosis are designed with the advanced virtual instrument software Lab-
VIEW which has the features of splendid interface and short development time comparing with other program languages. The interference
problem meet in debug phase is also researched deeply. This paper introduce several interference mode which are always
meet and put forward corresponding anti-jamming measure which has settled the interference problem.
Hydraulic pump fault diagnosis is a sub-function of the hydraulic pump comprehensive test bench. The common failure form of
hydraulic pump is studied and the correlated broken-down mechanics is analyzed deeply in this paper. Many method have been applied
on hydraulic pump diagnosis such as spectrum analysis, NN, wavelet analysis etc. This paper probes into the method of hydraulic
pump fault diagnosis by applying wavelet and fractal theory. Based wavelet theory this paper discusses several common methods
of signal to noise separation in this days and summarizes the merits and faults of each method and put forward wavelet filter method
based on lifting algorithm of the second-age translation invariant metric wavelet. It is used in the six chapter. Fractal theory is new
theory founded in eighties. The subject investigated which is researched is non-slippery and non-differentiable geometrical body in
nonlinear system. In the nature, the well-regulated phenomenon is special and approximate, irregular phenomenon is absolute. The
basic fractal theory is discussed in this paper, the associated dimension is used as sensitive gene for hydraulic pump fault diagnosis.
The associated dimension algorithm is researched and the parameters such as delayed time, embedded dimension, hypersphere radius
etc. are analyzed. Several types hydraulic pump common fault are simulated through building the simulation model of hydraulic
pump. The fault diagnosis simulation program is developed in virtual instrument LabVIEW based wavelet and fractal theory. It is
proved that it is feasible to use associated dimension as sensitive gene for hydraulic pump fault diagnosis, which provide a new
method for researching complicated problem and break a new path.
The thesis deals with the problem of output-feedback position tracking control of an electropneumatic actuator. The considered
application is a single-acting pneumatic cylinder operated by a three-way proportional valve, which is used for clutch actuation in
automated manual transmissions (AMT), and clutch-by-wire (CBW) solutions on heavy-duty trucks.
The main challenges are the high compressibility of air in combination with nonlinear flow and friction characteristics, and a
highly nonlinear clutch compression spring which constitutes the main load of the actuator. An additional complication, is that only
the position is measured and available for feedback control, i.e., an output-feedback control problem must be solved.
The first part of the thesis provides a unified treatment of the modeling of electro-pneumatic actuators in the context of nonlinear
and adaptive control. Next, it is shown that pneumatic actuators have some inherent stability properties which enable the design of
simple nonlinear observers. Based on this result, two nonlinear observers are proposed: a full-order observer and a simpler reducedorder
observer.
Finally, using the reduced-order observer, a robust output-feedback tracking controller is designed by a recursive backstepping
procedure in four steps, which enable explicit compensation of nonlinearities. Strong theoretical results are achieved, in particular,
exponential practical tracking in the presence of bounded disturbances, which can be made arbitrary accurate by sufficiently high
feedback gain in the observer and controller. The designed output-feedback controller is implemented on a test rig in the laboratory,
and high performance is demonstrated experimentally.
The goal of this work is to develop mathematical models, stability criteria, and control designs for a two-stage poppet valve system
with a simple back-side pipeline condition that may be used in a valve stack to create an independent metering function for a
hydraulic circuit.
First, this system is modeled as a nonlinear open-loop model as well as a linear one. The completely linear form of the flow force
acting on the poppet head is derived from simplified Navier-Stokes Equations. Second, four control methods that comprise modified
PI control, LQG control, H control, and nonlinear feedback control are used to make a closed-loop poppet system. The nonlinear
controller is only applied to the nonlinear system and certified by Lyapunov theorem to be globally asymptotically stable. The basic
guidelines for selecting control gains are derived by Routh-Hurwitz method. Finally, important system parameters, especially the
transient flow force and two leakages, are discussed to reveal their effects on the open-loop system stability. Simulations results
illustrate that the closed-loop poppet system with either the modified PI controller or the nonlinear controller can track the desired
poppet displacement represented by a sine wave with 10 HZ frequency. The LQG controller and the H controller having fixed
weighting functions or matrices are not flexible enough to satisfy the global nonlinear systems, though they exhibit the acceptable
regulation behavior.
One of the major drawbacks of a hydraulic system is the disturbing noise generated by the hydraulic pump. The pump flow ripple
is considered to be the most common source of noise in a positive displacement pump. Various studies suggesting modification of the
port-plate relief groove geometry and addition of hydraulic attenuators to reduce the flow ripple have shown a limited success in
reducing the noise. The noise level is still high and may not be acceptable for future applications. However, a recent industrial study
shows that the noise apparently has relation with the torque acting on the input shaft of the pump. The primary objective of this dissertation
is to describe two new methods to reduce the pump noise by attenuating the torque ripple. The analysis begins by deriving
the equation of the shaft torque as a function of the average torque and the total number of pistons that are used within the rotating
group. A control law is derived according to which if the swash plate is adjusted continuously, would give a constant shaft torque.
In a second method, two pumps are used in tandem, separated by an angle, which is shown to amplify or attenuate the torque ripple
amplitude depending on its value. It is shown that for the optimized value of the index angle, the torque ripple amplitude is reduced
by as much as 75%. The secondary objective of this dissertation is to present a Simulink model of a nine piston pump to
describe a functional pump. This model considers some leakage and fluid compressibility effects unlike the analysis part and hence
gives a more realistic outcome. The findings of the analysis are applied to this model. The results support the analysis and shows that
there is a link between the torque ripple and flow ripple, hence the torque ripple attenuation results in the flow ripple attenuation too.
Endless rolling system is a new technology applied in long material rolling system. it can removes the intervals between billets,
may greatly raises rolling productivity. Scientists abroad have done great researches, and studied out endless rolling system equipment,
but it is still blank at home. So it is significant to research this new technology. One of the key techniques of endless rolling
system is on flash butt weld of heavy-section heating billet.
Based on the key techniques, the dissertation designs virtual prototype of steel flash butt weld, hydraulic and control system of
flash weld. The dissertation also studies on the virtual integral experiment on software platform. The main research work and results
are shown as follows:
(1) The dissertation generalizes welding technology and key parameters adaptive to heavy-section billet, designs clamping hydraulic
system of pressure boosting and butt-joint hydraulic servo system. The analysis results indicate that the designed hydraulic
systems are satisfied to flash butt weld of heavy-section billet perfectly.
(2) Flash butt weld of heavy-section heating billet is divided into flash and upsetting stages, with different controlling requirements
at each stage. For this, position-pressure blending control system is used: position servocontrol at the flash stage; while pressure
servocontrol at the upsetting stage. Simultaneously the dissertation deduces transfer functions at each stage of hydraulic system
of flash butt weld of heavy-section heating billet.
(3) The dissertation puts forward a single neure controller which is similar to compound control, and concludes adjustment steps
of this kind of controllerfs parameters by simulation. The simulation results indicate, relative to compound controller, that the controller
possesses obvious advantage on the level of robustness, has simple structure, and is easy to real-time control.
(4) The dissertation induces the concept of directly inverse control, theoretically deduces the existence and structure of synchronous
error inverse model, and realizes the model by Adaline. The simulation results show that this method has certain advantage at
canceling pressure synchronous error at the upsetting stage.
(5) The feedback signal delayed in the sample system influences the pressure synchronous controller to regulate functions to
some extent, and the dissertation uses predictive controlling method of single neuro to predict synchronous error in current input,
which is directly carried on adjustment to two branches. The simulation results express that this controlling method can produce
significantly controlling effects, namely the dynamic synchronous error reduces obviously, the biggest dynamic error decreases from
8 MPa to 2.5 MPa.
(6) The dissertation establishes mechanical system model in ADAMS, control system model in Simulink, and hydraulic system
model in AMESim; and analyzes the interface characteristics between the softwares; designs co-simulation software platformGand
does the research on the virtual integral experiment.
(7) On the basis of the characteristics of flash butt weld of heavy-section heating billet, the dissertation establishes thermal model
of its hydraulic system. And with the same loading and simulation parameter condition, the dissertation doses simulation to the regular
and forced wind cooling conditions, and designs proper cooling conditions.
In this research, the four valve independent metering configuration is to be investigated. The Independent metering concept will
be emphasized and compared to spool valve coupled metering conventional technologies. Research focuses on the energy savings
potential of the four valve independent metering configuration in addition to improving performance.
The basic model of interest in this research is an actuator that is controlled by the four valve independent metering configuration
to move beam like members of mobile hydraulic equipment such as tractor loader backhoes, excavators, and telehandlers.
Five distinct (or discrete) metering modes that exist in the literature are initially studied: Powered Extension, High Side Regeneration
Extension, Low Side Regeneration Extension, Powered Retraction, and Low Side Regeneration Retraction. The energy saving
potential of these modes is studied and comparisons between this system and a conventional spool valve controlled actuator are
conducted.
The problem of switching between these five modes is treated as an optimal control problem of a switched dynamic system. Before
solving the optimal control problem, a dynamic model for the system of interest is first derived. The model is experimentally
validated.
General theory for the optimal control problem is derived and then applied to the hydraulic system of interest. The results are
then interpreted and explained by looking into the force-speed capability of modes.
The effect of mode switching on system performance is studied as well. The basic mechanical system used for this analysis is a
continuous rotating beam that undergoes structural vibrations due to mode switching in the driving hydraulic actuator. A fully coupled
actuator-beam model is investigated. A non-dimensional analysis is pursued to generalize the study results. The optimal switching
analysis and the vibrational study lead to the idea of Continuously Variable Modes (CVMs).
Instead of having five distinct modes that determines the flow path by opening two of the four valves in the assembly, three Continuously
Variable Modes are presented as an alternative way of controlling the four-valve configuration. These three CVMs combine
the distinct modes and use three of the four valves to provide the fluid flow path. The five distinct modes become a special case
of these three CVMs. It is going to be shown that CVMs have more force-speed capabilities than the distinct modes and provide for
better velocity and vibrational performance by virtue of always offering a continuous flow path. The theory behind CVMs is presented
and experimental validation follows.
The newly developed technique of hydrostatic transmission with secondary regulation, which can greatly enhance the efficiency
of hydrostatic transmission system. Based on the viewpoints mentioned above, the simulation test bench for engineering machinery
hydraulic chassis with secondary regulation is designed in this paper.
For the sake of requirements of theory analysis and project, the whole design scheme and technical demand of the simulation test
bench are introduced in detail, including driving system, loading system, test and control system, and vehicle special controllers. We
can see that this test bench is a highly automation and complicated mechnical-electrohydraulic system.
This paper theoretically analyses the basic working principle and the performance characteristics of hydrostatic transmission system
with secondary regulation and offers mathematics models of the system. The study results demonstrate that the damping, the
loading torque stiffness and stability of system be enhanced with double feedback controlling system (torque feedback and position
feedback). Also, it can provide theory for the enhancing the dynamic and static characteristics of the simulation loading system with
secondary regulation.
The mathematical model of the simulation test bench for engineering machinery hydraulic chassis is finished by modeling
method. And we analyses the influences on the torque loading system with secondary regulation in practical. Study of the model
shows that coupling relation lie in subsystems by the influence of hydraulic and mechanical coupling. The typical two_input
two_output coupling system is between the torque control of the loading subsystem and speed control of the driving. The decoupling
scheme based on single neuron PID is put forward in this paper, and simulations are engaged.
The mathematical model of the torque controlling subsystem with secondary regulation by mechanism modeling method cant
demonstrate its actual dynamic characteristics because it is complicated. So we conducted open loop identification method to identify
the model of the torque control system and got open loop mathematical model with certain parameter by the use of least square
method. This model provides advantages for the study of real time control and intelligent control laterly.
Theoretical analysis and study on PID control and human simulated intelligent control (HSIC) are engaged. Also the improved
principle of HSIC is given , and the controller of HSIC is designed, simulation to the torque control system with secondary regulation
is conducted. The control results of two controllers mentioned above are compared.
The simulation loading system with secondary regulation based on PROFIBUS-DP bus technology is designed and a large number
of experiments are done in this paper. Experiments of step response of torque control system are conducted under open and close
loop control systems and different torques. Furthermore, the characteristics of torque control system responding to square wave and
sine input signal, the influences on torque control system when different input signals are given to speed control system, the influences
on speed control system when different input signals are given to torque control system are also focused, and experiments are
put into effect. The conclusions responding to experiments above are given.
This study is concerned with the development of a portable pneumatic power source based on phase transition at the triple point
and a novel lower limb powered by it. The purpose of the study is to help the old people who have walking difficulties and can not
walk outdoors for long.
Firstly a novel portable pneumatic power source called Dry Ice Power Cell is developed which is applicable to self-powered mobile
applications such as wearable actuator and rescue robot etc. The dry ice, which is the solid phase of the carbon dioxide, is chosen
as the source of the power for the developed power source because it is nonpoisonous, easy to obtain, low in price and it expands 750
times in volume after being vaporized into the gas. When dry ice is stored in the confined pressure container, the pressure and temperature
rise by heat transfer and it begins to liquefy after the pressure and temperature reach the triple point (0.52[MPa(abs)], -
56C). In this process the pressure remains constant until all the dry ice melts into the liquid. When the state remains at triple point,
the pressure does not decrease even though the gas is released from pressure container. Accordingly, this means that the state can be
used as a stable pneumatic power source. By using this physical property of carbon dioxide at the triple point, and by controlling the
heat transfer from the surroundings into the pressure container, a noiseless, large capacity, light and portable pneumatic power source
is developed.
Secondly a novel pneumatic power assisted lower limb is developed by the use of a Dry Ice Power Cell as its power source. For
those people whose muscle and balance remains in good condition but who have joint pain (hip or knee joint) in their leg and are
unable to walk outdoors for long, the developed device can partially lift the patient in a comfortable way by pneumatic cylinder when
the affected leg touches the floor, reducing the loads to which it is subject as well as the pain joint forces, thus relieving pain during
walking. The developed device has the characteristics of a simple structure, low weight, easy to put on and take off and with sufficient
capability to bear about 40% of the body weight during about 1000 steps of outdoor walking, using the power of the Dry Ice
Power Cell. The developed device can assist with outdoor walking not only over flat ground but also sloped and stair areas.