Adaptive Integral Sliding Mode Based Course Keeping Control of Unmanned Surface Vehicle

This paper investigates the course keeping control problem for an unmanned surface vehicle (USV) in the presence of unknown disturbances and system uncertainties. The simulation study combines two different types of sliding mode surface based control approaches due to its precise tracking and robustness against disturbances and uncertainty. Firstly, an adaptive linear sliding mode surface algorithm is applied, to keep the yaw error within the desired boundaries and then an adaptive integral non-linear sliding mode surface is explored to keep an account of the sliding mode condition. Additionally, a method to reconfigure the input parameters in order to keep settling time, yaw rate restriction and desired precision within boundary conditions is presented. The main strengths of proposed approach is simplicity, robustness with respect to external disturbances and high adaptability to static and dynamics reference courses without the need of parameter reconfiguration.

Research on automobile four-wheel steering control system based on yaw angular velocity and centroid cornering angle

In order to improve the handling stability of four-wheel steering (4WS) cars, a two-degree-of-freedom 4WS vehicle dynamics model is constructed here, and the motion differential equation of the system model is established. Based on the quadratic optimal control theory, the optimal control of 4WS system is proposed in this paper. When running at low speed and high speed, through yaw rate feedback control, state feedback control, and optimal control, the 4WS cars are controlled based on yaw rate and centroid cornering angle with MATLAB/Simulink simulation. The result indicates that 4WS control based on the optimal control can improve the displacement of the cars. And, the optimal control of 4WS proposed in this paper can eliminate centroid cornering angle completely compared with other two traditional optimal control methods. Besides, the optimal control enjoys faster response speed and no overshoot happens. In conclusion, the optimal control method proposed in the paper represents better stability, moving track and stability, thereby further enhancing the handling property of cars.

Phase Portrait Trajectory of a 3DOF Vehicular Dynamic Model

This article formulates a front-wheel-drive three-degree-of-freedom (3DOF) four-wheel planar vehicle model with the Magic Formula tire model. The state variables' evolutions of the model, i.e., trajectories of the model under acceleration and deacceleration conditions, are analyzed. The process of evolution is divided into desirable and undesirable phases based on the response characteristics of the vehicle to the driver input during the process. The trajectories are categorized as unsaturated trajectories and saturated trajectories by the existence of saturated tires during these phases. The response of state variables to driver input under acceleration conditions during undesirable phases are zero or even opposite, while the response of undesirable phases under the deacceleration condition is partially positive. Besides, the existing yaw rate safety envelope is recalibrated by using a longitudinal and lateral tire force coupling model. A more accurate yaw rate safety envelope is obtained from the given driver input. Furthermore, a longitudinal speed safety envelope is proposed according to the relationships among slip angle, yaw rate, and longitudinal speed. These safety envelopes are determined by driver input, tire properties, and grip condition. After overlaying yaw rate and longitudinal speed safety envelopes in the state space, the feasibility of using the safety envelope as trajectory classification criteria is discussed.

Adaptive Integral Sliding Mode based Path Following Control of Unmanned Surface Vehicle

This paper investigates the path following control problem for a unmanned surface vehicle (USV) in the presence of unknown disturbances and system uncertainties. The simulation study combines two different types of sliding mode surface based control approaches due to its precise tracking and robustness against disturbances and uncertainty. Firstly, an adaptive linear sliding mode surface algorithm is applied, to keep the yaw error within the desired boundaries and then an adaptive integral non-linear sliding mode surface is explored to keep an account of the sliding mode condition. Additionally, a method to reconfigure the input parameters in order to keep settling time, yaw rate restriction and desired precision within boundary conditions is presented. The main strengths of proposed approach is simplicity, robustness with respect to external disturbances and high adaptability to static and dynamics reference courses without the need of parameter reconfiguration.

Torque vectoring control system for distributed drive electric bus under complicated driving conditions

Purpose The purpose of this study is to propose a torque vectoring control system for improving the handling stability of distributed drive electric buses under complicated driving conditions. Energy crisis and environment pollution are two key pressing issues faced by mankind. Pure electric buses are recognized as the effective method to solve the problems. Distributed drive electric buses (DDEBs) as an emerging mode of pure electric buses are attracting intense research interests around the world. Compared with the central driven electric buses, DDEB is able to control the driving and braking torque of each wheel individually and accurately to significantly enhance the handling stability. Therefore, the torque vectoring control (TVC) system is proposed to allocate the driving torque among four wheels reasonably to improve the handling stability of DDEBs. Design/methodology/approach The proposed TVC system is designed based on hierarchical control. The upper layer is direct yaw moment controller based on feedforward and feedback control. The feedforward control algorithm is designed to calculate the desired steady-state yaw moment based on the steering wheel angle and the longitudinal velocity. The feedback control is anti-windup sliding mode control algorithm, which takes the errors between actual and reference yaw rate as the control variables. The lower layer is torque allocation controller, including economical torque allocation control algorithm and optimal torque allocation control algorithm. Findings The steady static circular test has been carried out to demonstrate the effectiveness and control effort of the proposed TVC system. Compared with the field experiment results of tested bus with TVC system and without TVC system, the slip angle of tested bus with TVC system is much less than without TVC. And the actual yaw rate of tested bus with TVC system is able to track the reference yaw rate completely. The experiment results demonstrate that the TVC system has a remarkable performance in the real practice and improve the handling stability effectively. Originality/value In view of the large load transfer, the strong coupling characteristics of tire , the suspension and the steering system during coach corning, the vehicle reference steering characteristics is defined considering vehicle nonlinear characteristics and the feedforward term of torque vectoring control at different steering angles and speeds is designed. Meanwhile, in order to improve the robustness of controller, an anti-integral saturation sliding mode variable structure control algorithm is proposed as the feedback term of torque vectoring control.

An integrated control of front in-wheel motors and rear electronic limited slip differential for high-speed cornering performance

This paper presents an integrated control of in-wheel motor (IWM) and electronic limited slip differential (eLSD) for high-speed cornering performance. The proposed algorithm is designed to improve the handling performance near the limits of handling. The proposed controller consists of a supervisor, upper-level controller, and lower-level controller. First, the supervisor determines a target motion based on the yaw rate reference with a target understeer gradient. The target understeer gradient is devised to improve the lateral stability with in-wheel motor control based on a nonlinear static map. The yaw rate reference is designed based on the target understeer gradient to track the yaw reference with eLSD control. Second, the upper-level controller calculates the desired yaw moments for IWM and eLSD to generate the target motion. Third, the lower-level controller converts the desired yaw moment to the actuator torque commands for IWMs and eLSD. The tire friction limits are estimated based on the tire model and friction circle model to prevent tire saturation by limiting the torque inputs. The proposed algorithm has been investigated via both simulations and vehicle tests. The performance of the integrated control was compared with those of individual control and uncontrolled case in the simulation study. The vehicle tests have been performed using a rear wheel drive vehicle equipped with two front IWMs and eLSD in the rear axle. The vehicle test has been conducted at a racing track to show that the proposed algorithm can improve the lateral stability near the limits of handling.

Mechatronic Control Devices for a Modern Ship’s Magnetic Compass

One of the disadvantages of existing main magnetic compasses (МС) is the presence in their readings of an error from pitching due to the influence of centripetal and tangential accelerations when the MC is placed at a certain distance from the center rocking of the ship. This error can be unacceptably large, especially when using the compass in high latitude environments. This effect can be compensated by using a gyroscopic angular rate sensor (ARS), which measures the angular yaw rate of the ship. The work is devoted to the results of research and simulation of two correction system, which is introduced into the measuring circuit of the MC. Each of the correction systems presented in this work can be considered as mechatronic control device for a modern MC, one of them is positional, and the other is according to the angular yaw rate of the ship. The paper shows the advantages and disadvantages each of systems. So, a feature of the positional correction system is the need to use ARS of a tactical accuracy class (for example, a fiber-optic gyroscope). At the same time, the yaw rate correction system makes it possible to use a cheap micromechanical gyroscope (MMG). Despite the use ARS of various accuracy classes, both proposed correction systems allow achieving similar results, which leads to an obvious conclusion about the advisability of using the correction system with MMG, which allows to significantly reduce the cost of the MC, as well as to reduce its weight and dimensions.

A Mixed Sideslip Yaw Rate Stability Controller for Over-Actuated Vehicles

Electronic stability control (ESC) has become a fundamental safety feature for passenger cars. Commonly employed ESCs are based on differential braking. Nevertheless, electric vehicles’ growth, particularly those featuring an over-actuated configuration with individual wheel motors, allows for maintaining driveability without slowing down the vehicle. Standard control strategies are based on yaw rate tracking. The reference signal is model-based and needs precise knowledge of the friction coefficient. To increase the system robustness, more sophisticated approaches that include vehicle sideslip are introduced. Still, it is unclear how the two signals have to be weighted, and rarely proposed controllers have been experimentally validated. In this paper, we present a mixed sideslip and yaw rate stability controller. The mixed approach allows to address the control design as a single-input single-output problem simplifying the tuning process. Furthermore, we explain the rationale behind the choice of the weighting parameter. Eventually, the proposed ESC is validated following EU regulation in simulation and with an experimental vehicle on dry asphalt and snow. The results obtained in all the performed tests demonstrate that the proposed control strategy is robust and effective. The mixed approach is able to halve the sideslip in critical conditions with respect to a pure yaw rate approach.

Observer-Based Autopilot Heading Finite-Time Control Design for Intelligent Ship with Prescribed Performance

Traffic engineering control is a major challenge in marine transportation. Cost efficiency and high performance demand advanced technologies for the ship control systems. This paper develops an autopilot heading control scheme based on a fuzzy state observer for an intelligent ship on this subject to track the prescribed function while calling for performance limitation and order execution time. A fuzzy logic system (FLS) is adopted to approximate the unknown uncertainties caused by the changes in water depth, wind, wave, ship loading, and speed in navigation. State observer is required to obtain unknown yaw rate. By adopting performance function and tracking error transformation techniques, the heading tracking error can converge to prescribed performance bounds. Taking settling time into account, the finite-time adaptive prescribed performance control algorithm can save more resources effectively. Based on the Lyapunov stability theory, the observer-based adaptive fuzzy control approach does not cause any unbounded signal, the system remains stable. Meanwhile, the autopilot heading control system with an unknown yaw rate and constraint state can benefit from the given design.

Research on Stability of the Four-wheeled Robot for Emergency Obstacle Avoidance on the Slope

Background: In recent years, patents suggest that four-wheeled robots have been widely used in outdoor reconnaissance fields. However, the emergency obstacle avoidance of the four-wheeled robot on the slope is affected by the slope angle and the friction coefficient of the slope, and its motor torque and yaw torque are prone to abrupt changes, causing the four-wheeled robot to slip greatly. According to relevant literature, PID control methods (dual-loop PID control and linear PID control) make the robot control motor current fluctuate greatly during the emergency obstacle avoidance process. Hence, the PID controller of the four-wheeled robot needs to be optimized. Objective: This study aims to establish a novel dual-loop fuzzy PID controller to improve the stability of the four-wheeled robot during emergency obstacle avoidance on the slope. Methods: Establishing the kinematics and dynamics equations of the four-wheeled robot, and determining the speed of the center of mass and the yaw rate are important control parameters for controlling the steering motion of the robot. Aiming at the PID controller of the past four-wheeled robot, its response speed is slow, and the overshoot of the speed of the center of mass and the yaw rate is large. For this reason, the dual-loop fuzzy PID controller is designed. Comparison simulation is carried out by the MATLAB programming. Results: It is concluded that the control effect of the four-wheel robot with the dual-loop fuzzy PID controller is the best. The steering angle and displacement response speed of the four-wheel robot are faster, and there is basically no overshoot. The response of the yaw rate is increased by 30%, the average deviation of the linear motion trajectory is reduced by 41.27%, and the average deviation of the circular steering motion trajectory is reduced by 29.51%. Conclusion: The dual-loop fuzzy PID controller can provide reference for the PID control research of other four-wheeled robots.