Lateral Control for Unmanned Ground Vehicle with Anti-Peak Composite Nonlinear Extended State Observer

Author(s):  
Haoyu Wang ◽  
Zhiqiang Zuo ◽  
Yijing Wang
Author(s):  
Suraj Shamrao Borate ◽  
Shubhashisa Sahoo ◽  
Devika K. Baby ◽  
Shankar C. Subramanian ◽  
Kiran K. Mangrulkar

This paper deals with tracking of desired yaw rate generated by the path planner of an Autonomous Ground Vehicle (AGV) in the presence of unmodeled dynamics, changes in operating conditions and parametric uncertainties. A mathematical model considering the dynamics of the test vehicle and the steering actuator was used for controller design. The estimate of the unknown part of dynamics, called the total disturbance, obtained from the Extended State Observer (ESO) was used by Sliding Mode Controller (SMC) to compensate the actual total disturbance. It was observed that the lower bound on the SMC switching gain depends on the ratio of total disturbance estimation error and assumed known part of the system dynamics. This allows the choice of a low value of SMC switching gain, which in turn resulted in reduced chattering amplitude. Further attenuation in chattering was achieved using a saturation function. After simulating the designed controller in MATLAB-SIMULINK environment, the controller was validated in IPG: CarMaker® simulation platform over a large operating range by changing the mass distribution of the vehicle, speed of the vehicle, cornering stiffness of the tire and terrain friction coefficient. A look-up table was formulated for the maximum achievable yaw rate at different speeds, i.e., from 5 to 20 m/s, given the maximum steering angle input considering rollover and slip threshold while the terrain friction coefficient was also varied from 0.2 to 0.8. It was observed that the designed controller was robust to changes in operating conditions, parametric uncertainties and unmodeled dynamics.


Energies ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1651 ◽  
Author(s):  
Amjad J. Humaidi ◽  
Ibraheem Kasim Ibraheem

In this paper, a novel finite-time nonlinear extended state observer (NLESO) is proposed and employed in active disturbance rejection control (ADRC) to stabilize a nonlinear system against system’s uncertainties and discontinuous disturbances using output feedback based control. The first task was to aggregate the uncertainties, disturbances, and any other undesired nonlinearities in the system into a single term called the “generalized disturbance”. Consequently, the NLESO estimates the generalized disturbance and cancel it from the input channel in an online fashion. A peaking phenomenon that existed in linear ESO (LESO) has been reduced significantly by adopting a saturation-like nonlinear function in the proposed nonlinear ESO (NLESO). Stability analysis of the NLEO is studied using finite-time Lyapunov theory, and the comparisons are presented over simulations on permanent magnet DC (PMDC) motor to confirm the effectiveness of the proposed observer concerning LESO.


Author(s):  
Chao Lai ◽  
Weihong Wang ◽  
Zhenghua Liu ◽  
Zheng Ma

A neuro-adaptive fast terminal sliding-mode dynamic surface control method based on a finite-time stable nonlinear extended state observer is applied to integrated guidance and control design for skid-to-turn missile attacking a ground maneuvering target with terminal angle constraints. A three-dimensional integrated guidance and control design model against a maneuvering target for skid-to-turn missile is established without the assumption that the missile velocity vector and the line of sight coincide with each other. The non-singular fast terminal sliding surface is applied to construct the first error surface of dynamic surface control and the first virtual control law is designed to guarantee hitting accuracy with desired terminal angles. The finite-time stable nonlinear extended state observer is designed separately to estimate uncertainties in the system. And the neuro-adaptive technique is applied to compensate estimation errors of nonlinear extended state observer by training a three-layer feedforward neural network online. Synthesizing all of above, a neuro-adaptive fast terminal sliding-mode dynamic surface control based on nonlinear extended state observer is derived on Lyapunov stability theory, which guarantees stability of the system. Finally, the numerical simulations are conducted to demonstrate the effectiveness of the proposed three-dimensional integrated guidance and control scheme.


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