|Place of Conferral||北京|
|Keyword||铰接转向式履带车 铰接机构 液压伺服 履带同步控制 路径跟踪|
Articulated steering tracked vehicle (ASTV, also called All terrain vehicle)
is kind of double tracked vehicles hinged by a articulated mechanism to achieve
steering, pitching and rolling between the two. ASTV has the advantages of low
ground pressure, high mobility and good adaptability to rough terrain, which equipped
it to deal with many applications, such as military affairs, polar science,
engineering, disaster relief and so on. As the requirement for ASTV increases,
higher performance is in great demand as well. Key technologies especially
the coordination control issue of front and rear vehicle has made tardy progress
recently and still lags behind foreign countries. Therefore, the key control technology
of ASTV should be solved urgently. Key control issues of ASTV were
studied and design of the control system were discussed in this thesis. And the
main contents of this thesis are as follows:
Firstly, the research significance of ASTV is presented and the former research
work of ASTV is reviewed. The existing technique nodus are then summarized.
According to the key research focuses of this paper, main research methods
and current conditions of those key control techniques are introduced.
Secondly, the experimental prototype of mechanical structure for ASTV is
designed and manufactured, including the articulated mechanism, the front vehicle
and the rear vehicle. Aiming at functional requirements of hinge mechanism,
a 4-DOF articulated mechanism and its hydraulic control system are firstly designed.
Then the kinematics of the articulated mechanism is derived and its
motion performance is analysed. The key design gist of the undercarriage and
the driving mechanism of the tracked vehicle are presented finally.
Thirdly, the kinematic model and dynamic model of ASTV driving on different
terrain are derived. Based on the relationship between the vehicle speed and
slip ratio, the kinematic models of ASTV straight driving and steering are built,
respectively. As the interaction between the track and soft ground is different
from firm ground, the forces acting on ASTV straight driving and steering on both grounds are analysed. And based on the equilibrium relationship between
force and torque, unified dynamic model is built and discussed.
Fourthly, an adaptive backstepping based electro-hydraulic(E-H) control
method is proposed for the motion control issue of articulated mechanism. The
motion control issue of articulated mechanism is converted into the issue of hydraulic
servo control at first, then the model of E-H control is built based on the
basic equations of E-H system. Aiming at the nonlinear uncertain parameters
of the model, integral-type Lyapunov function is defined to transform them to
linear parameters. An adaptive backstepping based E-H control method is proposed.
And the problems of parameter-drift and external disturbance are solved
by the parameter update laws based on sufficiently smooth projection operators
and the added nonlinear-damping item. A cosimulation platform using AMESim
and Matlab is build and the efficiency of the proposed algorithm is validated.
Fifthly, an adjacent cross-coupling structure based adaptive sliding-mode
synchronization control algorithm is proposed for the synchronization issue of
ASTV’s four tracks. The relation models of steering angle, the speed of the vehicle
and the speed of four tracks are built. Based on the adjacent cross-coupling
method, a synchronization control structure of four tracks is designed. Aiming
at the uncertain parameters and external disturbance of the system, a disturbance
observer based adaptive sliding-mode controller is proposed. The effects
of external disturbance are inhibited by designed linear and nonlinear disturbance
observer. The chattering phenomenon is reduced by the proposed boundary layer
adaptive algorithm, which is verified in the simulation environment.
Sixthly, an adaptive fuzzy sliding-mode controller is proposed for the path
tracking issue of ASTV. One tracking error model on occasion of slip angles
is established. Aiming at the uncertainty and nonlinear characteristics of the
system caused by the slip angle, an adaptive law of uncertain parameters is
designed based on Lyapunov stability theory to deal with the unknown slip angle.
And a sliding-mode controller with switching function is designed to reduce the
effects of the disturbance merged with the nonlinear term. Then considering
the chattering problem caused by the switching function, a fuzzy approximator is proposed to make the switching function continuous. Moreover, the fuzzy
approximator is also an identifier to the unknown upper bound of the disturbance.
It is verified by simulations that the proposed algorithm is effective for path
tracking control of ASTV.
Seventhly, a hierarchical control structure is adopted to construct the control
system of ASTV in consideration of mechanics and working environment. Some
experiments are carried out to test the movement performance. The designed
hydraulic system of the articulated mechanism is firstly implemented. Steering
and pitching motion experiments are then carried out. Due to the large size
and mass of the hydraulic control system and under the premise of maintaining
the same degree of freedom, an articulated mechanism driven by motor is designed.
Based on the modular design method, the control system of ASTV is
established with the hierarchical control structure. Owing to the expansibility
design concept, the control system can be compatible with both hydraulic and
motor-driven articulated mechanism at the same time. At last, the motion and
obstacle-surmounting experiments of ASTV are performed.
|林浩. 铰接转向式履带车关键控制技术研究[D]. 北京. 中国科学院研究生院,2016.|
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