Hydraulic Steering System Research Articles

Steering control for handling and stability and wear resistance of multi-axle vehicles

The steering performance of a vehicle directly affects its handling and stability, and tire wear during steering. For multi-axle vehicles equipped with a mechanical hydraulic steering system (MHS), this paper describes a steering-by-wire hydraulic system (SHS) for a third axle that can reduce the steering wear of third-axle tires while improving the handling and stability. A hydraulic steering system based on a reliable self-locking alignment cylinder was designed in this study, and a nonlinear dynamics model of a multi-axle vehicle was developed. In terms of the control strategy, the upper controller was a decision selector with a lateral acceleration threshold of 0.3 g , at which point the system entered the nonlinear kinematic state as a criterion for decision-making. The suboptimal linear time-varying model predictive control (S-LTV-MPC) method or Ackermann steering theory was used to calculate the target steering angle of the third axle. The lower controller was a fuzzy proportional–integral–derivative controller for tracking the steering angle of the third axle. The simulation and test results showed that the S-LTV-MPC method can meet the requirements of real-time control and accuracy. The designed SHS exhibited good handling and stability, and anti-wear properties during steering.

Review on the development and optimization of steering systems for autonomous vehicles

The steering system of an automobile is an extremely important part. The development of unmanned driving technology has put forward new requirements for the steering system. This paper summarizes the three mainstream steering systems in the market, combines them with the requirements of automatic driving technology, and compares and analyses their strengths and disadvantages. The optimal solution of a steering system in the field of automatic driving is given, and research on the development of steering systems in the future is focused. The conclusion is that hydraulic steering system is not suitable for the use of autonomous vehicles. At present, most autonomous vehicles use EPS, but EPS has limitations. The steer-by-wire system under research will be widely used in the field of autonomous driving in the future.

PSO-Based Variable Parameter Linear Quadratic Regulator for Articulated Vehicles Snaking Oscillation Yaw Motion Control

In this paper, the seven degrees of freedom (DOF) nonlinear system model of articulated vehicles, including the vehicle dynamics model, tire and hydraulic steering system model, and the linearized ideal reference model, is constructed. A layered stability controller for the articulated vehicle is built. The particle swarm optimization (PSO)-based variable parameter linear quadratic regulator (LQR) for the upper-level yaw torque controller and the lower-level torque distributor based on the principle of the minimum tire utilization are established. The effectiveness of the LQR upper-level yaw torque controller for an articulated vehicle at different speeds and control references are compared and analyzed through feedforward and feedback control. We optimize the parameters in the LQR controller using PSO and verify the improvement in the controller’s performance with optimized parameters. Overall, the effect of front and rear-integrated control is best, followed by rear-based and front-based control. The PSO algorithm to optimize the LQR controller parameters for snaking oscillation control is effective.

Design and control performance optimization of dual-mode hydraulic steering system for wheel loader

The traditional wheel loader performs the steering operation by the rotation of the steering wheel, which significantly increases the complexity and fatigue of the operator. This paper presents a dual-mode steering system to solve the afore-mentioned problems, where a pilot control valve with a joystick is connected in parallel with the redirector to control the hydraulic steering system. The steering speed and angle of the loader can be controlled by the swing angle and time of the joystick. Based on the simulation and experimental results, the proposed system has the same trend of pressure variation and good steering performance compared with the traditional steering system. The hydraulic damping diameter matching the steering system is obtained by simulating and optimizing the equivalent model. The experimental results show that the effective control swing angle of the joystick increased from 12.5° to 19.7°, which improves the control accuracy of the steering system.

Design of a deviation detection sensor and an auto-follow row system for corn harvesters

The auto-follow row technology is the basic technology to realize the uncrewed operation of corn harvesters, which helps to improve the quality and efficiency of corn harvest. A deviation detection sensor and an auto-follow row system are designed to address the difficulty for corn harvesters to harvest the corn sowing with different row spacing. The auto-follow row system is comprised of the auto-follow row controller, two deviation detection sensors, sensors for acquiring the state of the corn harvester, and the hydraulic steering system. The deviation detection sensor uses the touch rod to detect the lateral deviation and sends it to the auto-follow row controller through the Controller Area Network (CAN) bus. The auto-follow row controller obtained the lateral deviation, calculated the target steering angle according to the pure pursuit method based on the yaw angle estimation model and fuzzy control model, and adjusted the posture of the harvester by controlling the steering actuator. Two types of corn harvesters were reformed and mounted the auto-follow row system for simulation and field tests. The average errors of the auto-follow row system in the simulation tests and the field tests were 0.040 m and 0.046 m, respectively. The relative deviations within ±0.075 m were 98.33% and 97.22%, respectively, which met the operating requirements of corn harvesters. The test results show that the auto-follow row system can be applied to many kinds of corn harvesters and provide a reference for designing a completely unmanned system for corn harvesters.

Closed-Circuit Pump-Controlled Electro-Hydraulic Steering System for Pure Electric Wheel Loader

Traditional construction machinery’s full hydraulic steering system has high energy consumption. An electro-hydraulic flow matching steering system for electric wheel loaders based on closed-circuit pump control is proposed to solve the problem. The transfer function of the electro-hydraulic system is established, and the system is stable according to analysis via Routh matrix. A test platform is built to verify the effectiveness of the system and the control strategy. Taking a 1.6T wheel loader as an example, the energy consumption of the traditional steering system and the new steering system under zero-load, positive-load (shovel loaded with 600 kg gravel), and offset-load (the center of gravity of the gravel is off the center of the bucket) conditions is compared. The results show that the energy consumption of the proposed steering system is greatly reduced compared to the traditional system. Under the condition of zero-load with medium steering speed, compared to the traditional system, consumption is reduced by 22.8%.

Research on Steering Vibration Analysis of Wheel Loader and Cushion Valve Design

At present, the wheel loaders on the market have steering vibration problems, which can be summarized as follows: the front frame and the cab vibrate violently at the beginning and at the end of steering. This paper analyzed the steering vibration mechanism by collecting the pressure at different positions of the hydraulic steering system and AMESim simulation. A cushion valve was designed to solve the problem of steering vibration. Finally, the prototype test was carried out and it was concluded that the cushion valve reduced the steering pressure starting shock by 50%, the stop vibration was reduced by 75%, and the suction problem no longer occurred. Further, the analysis provides theoretical and experimental basis for research on the steering system of loaders, and also provides new ideas for the design and optimization of vehicle steering systems.

Impact of Hydraulic System Stiffness on Its Energy Losses and Its Efficiency in Positioning Mechanical Systems

Hydraulic steering systems for mechanical devices, for example, manipulators or vehicle steering systems, should be able to achieve high positioning precision with high energy efficiency. However, this condition is very often not met in practical applications. This is usually due to the stiffness of the hydraulic system being too low. As a result, additional corrections are required to achieve the required positioning precision. Unfortunately, this means additional energy losses in the hydraulic control system. In this study, this problem is presented using the example of a hydraulic steering system for an articulated frame steer vehicle. This hydraulic steering system should provide the required directional stability for road traffic safety reasons. So far, this issue, connected mainly with the harmful phenomenon of so-called vehicle snaking behaviour, has not been solved sufficiently practically. To meet the needs of industrial practice, taking into account the current global state of knowledge and technology, Wrocław University of Science and Technology is performing comprehensive experimental and computational studies on the snaking behaviour of an articulated frame steer wheeled commercial vehicle. The results of these tests and analyses showed that the main cause of problems that lead to the snaking behaviour of this vehicle class is the effective torsional stiffness of the hydraulic steering system. For this reason, a novel mathematical model of the effective torsional stiffness was developed and validated. This model comprehensively took into account all important mechanical and hydraulic factors that affect the stiffness of a hydraulic system, resulting in the examined snaking behaviour. Because of this, it is possible at the design stage to select the optimal parameters of the hydraulic steering system to minimise any adverse influence on the snaking behaviour of articulated frame steer wheeled vehicles. This leads to minimising the number of required corrections and minimising energy losses in this hydraulic steering system. The innovative model presented in the article can be used to optimise positioning accuracy, for example, in manipulators and any mechanical system with hydraulic steering of any system of any mechanical parts.

A Skid-Steering Method for Path-Following Control of Distributed-Drive Articulated Heavy Vehicles

Distributed-drive articulated heavy vehicles (DAHVs) have separate front and rear sections and require a complex hydraulic steering system to achieve the steering process, which poses considerable challenges in obtaining better steering characteristics and achieving path-following control. In this paper, the distributed-drive characteristic of DAHVs is used to develop a novel skid-steering method (SSM) in which the hydraulic steering method (HSM) is replaced with a system that differentially controls the driving wheels to improve vehicle steering performance and path following control accuracy. Three main contributions are made: 1) The novel SSM with direct yaw moment that is used to be the sole power source during steering process of DAHVs is designed to replace the conventional HSM. 2) The idea of SSM by yaw rate control of one vehicle section to achieve the steering process for DAHVs is proposed firstly, which can solve the complex problem of requiring multiple control parameters due to the separate vehicle sections of DAHVs. 3) A layered control method is implemented to improve the robustness of the control system, which is composed of an upper path following controller and a lower skid steering controller combined with a double sliding mode control technique. The system’s stability and robustness are proven by the Lyapunov approach. A co-simulation model verified by field tests is used to demonstrate the feasibility and effectiveness of the proposed control method. The results of this study provide a new way to improve the intelligence of DAHVs.

Design and experiment of multi-mode steering system of agricultural machinery for hilly and mountainous area

In order to improve the steering flexibility of agricultural machinery in hilly and mountainous areas, a multi-mode steering system with front wheel steering, rear wheel steering, and four-wheel steering has been developed. The hydraulic steering system based on load sensitivity principle and proportion-integration-differentiation (PID) controlling algorithm was designed, which overcomes the negative impact of external load changes on flow control accuracy. The mechanical-hydraulic-controlling coupling model established in the AMESim and the sequential quadratic combinatorial optimization algorithm (SQCOA) was adopted to obtain the optimal combination of PID parameters. The simulation results demonstrate that the parameters such as pressure, speed, displacement of hydraulic cylinders, etc. in different steering modes meet the design requirements. To examine and verify the system performance, the test platform was researched and developed for conducting steering radius and displacement measurement. The experimental data illustrated that the front and rear hydraulic cylinders have good synchronization accuracy in four-wheel steering mode, and the fast switch of steering mode can be realized. The maximum error rate of is steering radius 4.21% and 3.77%, respectively, in two-wheel steering and four-wheel steering modes. The research methods and conclusions can provide a theoretical basis and reference for the other steering system development.

Development of alternative steering models for ev bus: a preliminary study on the conversion of hydraulic to electric power steering

This study aims to develop alternative steering models for the EV bus. The EV bus uses its energy source from the main 384 VDC 300 Ah battery and the secondary battery with a capacity of 25.8 VDC 100 Ah. The use of energy in this electric bus is divided into the main components, namely the BLDC motor as the main drive of 200 kW, 15 kW of air conditioning, 7.5 kW of hydraulic power steering, a compressor for the air braking system of 4 kW, and accessory components. The other is 2.4 kW. It is expected that this 7.5 kW electric power can be reduced by an electric system by up to 20 %. This research will study the steering system with an electric power system (EPS) to convert the hydraulic steering system (HPS). With this EPS system, it is hoped that controlling the vehicle’s motion towards the steer by wire will be easier. Initially, data were collected from the types of large vehicles from various well-known brands about the steering system used. A large commercial vehicle that purely uses EPS is not yet found. The model developed for EPS on this electric bus is through the reverse engineering method by redrawing all the components involved in the previous steering system. Because this type of EV bus is included in the upper mid-size class, this paper proposes two new EPS models, namely the addition of an assist motor on the drag link and on the steering rack. The links involved in this system are wheel drive, steering column, lower steering column, rack and pinion gear, assist motor, drop link, drag link, drop link extension, drag link extension, tie rod, knuckle, kingpin, tire, axle beam and several others. The values of stiffness, inertia, and damping of each link will affect the driver’s torque and the assist motor as a wheel speed function on this electric bus. The steering structure of the EV bus consists of a truss structure and a frame structure with a kinematic structure consisting of two four-bar linkages joined together

Impulse Control Technology for Improving Steering Control Systems of the Tracked Vehicles

Ensuring the maneuverability of forest track machinery is of great interest to the forest industry in reducing the negative impact on the soil and increasing the productivity of forestry operations. This work aims to develop an improved impulse steering control technology to improve forest-tracked machinery maneuverability. The "diagonal" steering control system combined with the 5-15 Hz pressure impulse width modulation in the hydraulic steering control system was employed. Various modulator designs and steering control system parameters were selected, serving as the basis for developing an experimental prototype of the steering control system. The results of the experiment showed that the proposed technology allows creating conditions suitable for applying the impulse steering technology with minimal changes in the transmission design. The obtained results demonstrate the reliability and stability of the machine's steering system with an onboard gearbox in all parameters during shifting and turning operations. These results may be useful in designing steering control systems of tracked vehicles. The future study can focus on developing and testing the control system for a modernized skidder chassis.

Modelling and Stability Analysis of Articulated Vehicles

This study constructs a nonlinear dynamic model of articulated vehicles and a model of hydraulic steering system. The equations of state required for nonlinear vehicle dynamics models, stability analysis models, and corresponding eigenvalue analysis are obtained by constructing Newtonian mechanical equilibrium equations. The objective and subjective causes of the snake oscillation and relevant indicators for evaluating snake instability are analysed using several vehicle state parameters. The influencing factors of vehicle stability and specific action mechanism of the corresponding factors are analysed by combining the eigenvalue method with multiple vehicle state parameters. The centre of mass position and hydraulic system have a more substantial influence on the stability of vehicles than the other parameters. Vehicles can be in a complex state of snaking and deviating. Different eigenvalues have varying effects on different forms of instability. The critical velocity of the linear stability analysis model obtained through the eigenvalue method is relatively lower than the critical velocity of the nonlinear model.

Design and Test of Auxiliary Steering System of High Clearance Sprayer Chassis Based on Self-steering Structure

A hydraulic assisted steering method was proposed to solve the problem of steering instability caused by insufficient reverse resistance moment of wheel hub motor in four-wheel independently electrically driven high clearance sprayer. Firstly, the principle of steering chassis structure of four-wheel independently electrically driven high clearance sprayer is briefly introduced. On this basis, hydraulic auxiliary steering system is designed. Then a simplified 2-DOF vehicle steering model is established to analyze the Angle control of the auxiliary steering system. Finally, simulation and road surface test are carried out respectively to verify the performance of steering and auxiliary steering coordination control. Under the working conditions of the steering system alone and the steering system and the auxiliary steering system together, the four-wheel electric drive sprayer carried out the obstacle crossing test and the downslope test with the slope of 15° respectively at the speed of 1 m/s on the smooth road surface. The test results show that in the downhill test, the maximum tracking deviation of the steering system alone is 6.1°, the maximum tracking deviation of the steering and auxiliary steering coordination is 0.9°, the maximum tracking deviation of the steering system alone is 12.0°, and the maximum tracking deviation of the steering and auxiliary steering coordination is 1.2° in the obstacle breaking test. The test results verify the feasibility and stability of the hydraulic steering system proposed in this paper. The system has good test performance and can meet the practical requirements.

Dynamic modelling and stability analysis of the articulated tracked vehicle considering transient track-terrain interaction

Articulated tracked vehicles (ATVs) exhibit enhanced steerability but reduced yaw stability. Apart from the track-terrain contact, the dynamics of the articulated frame steering (AFS) system strongly influences the stability of ATVs. We developed a detailed hydraulic steering system and a yaw-plane ATVs model for vehicle stability research. The transient characteristic of track-ground contact was considered. The multibody dynamics model by Recurdyn/Track software was compared with the established model to verify the model correctness at time-domain and frequency-domain. The result suggests that the vehicle yaw stability can be evaluated in terms of the oscillation frequency, damping ratio, overshoot, and steady-state deviation of articulation angle response. A multi-objective optimization is proposed to obtain the optimized structural parameters of AFS system by employing response surface method (RSM) and non-dominated sorting genetic algorithm II (NSGA-II). The optimal solutions revealed that more compact mechanism design of AFS system contributes to a compromise stability performance with 4.44 % decrease in the oscillation frequency and 10.3 % decrease in the damping ratio.

Mechanical-Hydraulic Co-Simulation of Full Hydraulic Articulated Steering System

With the development and improvement of the hydraulic steering system, the articulated steering system became the research focus of numerous domestic and foreign scholars. The full hydraulic steering system with a compact s... | Find, read and cite all the research you need on Tech Science Press

A hierarchical adaptive control framework of path tracking and roll stability for intelligent heavy vehicle with MPC

Roll stability is a major concern in the path tracking process of intelligent heavy vehicles in emergency steering maneuvers. Due to the coupling of lateral and roll motions of heavy vehicle, steering actions for path tracking may come into conflict with that for roll stability. In this paper, a hierarchical adaptive control framework composed of a supervisor, an upper controller and a lower controller is developed to mediate conflicting objectives of path tracking and roll stability via steering control. In the supervisor, path tracking control mode or cooperative control mode of path tracking and roll stability is determined by the predicted rollover index, and a weight function is introduced to balance the control objectives of path tracking and roll stability in cooperative control mode. Then, in order to achieve multi-objective real-time optimization, model predictive control with varying optimization weights is used in the upper controller to calculate the desired front steer angle. The lower controller which integrates the real electrically assisted hydraulic steering system based on Proportional-Integral-Derivative control is designed to control steering wheel angle. Simulation and hardware-in-loop implementation results in double lane change scenario show that the proposed hierarchical adaptive control framework can enhance roll stability in emergency steering maneuvers while keeping the accuracy of path tracking for intelligent heavy vehicle within an acceptable range.

Ride and roll/yaw stability analysis of articulated frame steer vehicle with torsio-elastic suspension

An articulated frame steered vehicle model with torsio-elastic suspension is established in Adams/View. The model considered the influence of the hydraulic steering system on the yaw stability of articulated vehicles, thus, the hydraulic steering system is formulated and modeled in MATLAB/Simulink. The ride and roll/yaw stability of the vehicle model is investigated via co-simulation of Adams and Simulink. The Adams vehicle model is verified based on the vibration acceleration responses near the seat position at constant forward speeds. The hydraulic steering system model is validated through the steady-state steering maneuver. Relative ride performance of unsuspended and fully suspended vehicle is investigated in terms of unweighted and frequency-weighted root-mean-square accelerations. The roll and yaw stability of vehicle model with and without suspension at loaded and unloaded conditions are subsequently analyzed in terms of roll angle, roll safety factor, lateral acceleration, critical speed, and so on. The results show that the torsio-elastic suspension can efficiently reduce the vibrations of the vehicle, and the articulated frame steer vehicles applied with torsio-elastic suspension yield slightly lower roll/yaw stability but substantial reductions in the ride vibration levels. The results provide some reference for the suspension and steering system design of articulated engineering vehicle.

A novel assist-steering method with direct yaw moment for distributed-drive articulated heavy vehicle

This paper presents a novel assist-steering method for distributed-drive articulated heavy vehicles (DAHVs) to reduce its dependency on hydraulic steering method and improve the pressure characteristics of hydraulic struts. The objective is to realise the electrification of steering process for DAHVs, which is the basis of unmanned design with more stable control in the following studies. The theory and purpose of the proposed assist-steering method in this paper distinguishes it from the traditional direct yaw-moment control method or assist-steering methods in the previous studies, which easily produce interference with hydraulic steering method in DAHVs during steering process. In this paper, an accurate vehicle model is developed along with the field test for its satisfactory verification. Meanwhile, with the decoupling analyses of two different effects of steering methods on vehicle steering process, the assist-steering method is developed. In order to show the advantages brought on by this method, a case study is performed and analyzed. The results demonstrate that this proposed method can reduce the pressure of hydraulic steering system to about 41.2% without any changes of steering process, which is limited by the drive ability of wheel-side motor. Moreover, the pressure of inlet chamber in hydraulic struts is always reduced to about 40%–60% without any changes of the pressure in outlet chamber, which can improve the working performance of hydraulic steering system.

Study of Hydraulic Steering Process for Articulated Heavy Vehicles Based on the Principle of the Least Resistance

This paper presents a new model for the hydraulic steering mode of articulated heavy vehicles (AHVs). The objective is to obtain the more accurate vehicle performance during steering process. The dynamic analyses of the hydraulic steering system, and the kinematic analyses of steering mechanical structure, including the steering wheel, articulation joint, and struts provide the constraints for the study of steering process with the principle of the least resistance. Meanwhile, a three-DOF dynamic model is developed to analyze the force characteristics of vehicle components. In order to verify the model, field tests and the comparisons with existing research works are performed. The results show that the present model is more effective and similar with the real steering process of AHVs. Moreover, another three conclusions can also be drawn: 1) Only 20% of the hydraulic pressure provides steering driving force. The rest is wasted, which is used to overcome the resistance of outlet pressure in hydraulic system itself. 2) The lateral resistance of each wheel is much greater than the longitudinal, but for the energy consumptions of lateral direction only accounting for 0.1% of longitudinal. Therefore, the lateral forces cannot be ignored in the dynamic model. But for the control strategy with minimum energy consumption, it is useless to consider the energy of lateral impact. 3) Road conditions or vehicle parameters such as the load, the wheel tread, or the wheel base, influence wheel resistances easily, which further influence the vehicle steering process. Furthermore, the vehicle trajectory and differential forces of each wheel obtained from the model are credible to be the reference of intelligent control for AHVs.