Solution of steering angle based on homogeneous transformation

Steering Angle is related to the design and optimization of steering mechanism and suspension, but it is not equal to the angle of knuckle around kingpin because of the existence of wheel alignment parameters. To calculate the steering angle, this paper derives based on homogeneous transformation its function expression by analyzing spatial geometric relation between the two angles and calculating coordinates related to steering trajectory of wheel center. Then, multi-body model of McPherson suspension with steering system is built and the calculation correctness is verified by comparing the function curve plotted by MATLAB software with the curve simulated by Adams/Car software. The calculation and simulation indicate that between the two angles, there is a ratio which is related to wheel alignment parameters and greater than 1.

A Shared Aperture Microstrip Antenna Array with Multiple Polarisations and Near-Field Beam Steering

In this paper we present a shared-aperture polarisation reconfigurable microstrip array designed to resonate at 11.5 GHz with a gain bandwidth of 2 GHz (~17%). The polarisation reconfigurability (both linear and circular) is achieved using two orthogonal and independently-fed sub-arrays that are intertwined together on the same aperture. Each subarray is fed through one port and a feed network that distributes the power among the array elements incorporating Taylor taper distribution to minimize the sidelobe level. The array has low cross-polarisation level (<-20 dB) and good port isolation (<-24 dB). The shared aperture and absence of active switching devices provide better control of polarisation selection with almost no insertion loss. A near-field metasurface based steering system is also presented and applied to the array for one- and two-dimensional beam steering. The results are verified through model simulations and measurement of the fabricated prototypes.

A Shared Aperture Microstrip Antenna Array with Multiple Polarisations and Near-Field Beam Steering

In this paper we present a shared-aperture polarisation reconfigurable microstrip array designed to resonate at 11.5 GHz with a gain bandwidth of 2 GHz (~17%). The polarisation reconfigurability (both linear and circular) is achieved using two orthogonal and independently-fed sub-arrays that are intertwined together on the same aperture. Each subarray is fed through one port and a feed network that distributes the power among the array elements incorporating Taylor taper distribution to minimize the sidelobe level. The array has low cross-polarisation level (<-20 dB) and good port isolation (<-24 dB). The shared aperture and absence of active switching devices provide better control of polarisation selection with almost no insertion loss. A near-field metasurface based steering system is also presented and applied to the array for one- and two-dimensional beam steering. The results are verified through model simulations and measurement of the fabricated prototypes.

Features of driving of the steering wheel driving cars

Existing methods of diagnosing steering can be characterized by low efficiency. For various reasons, both declarative and actual (supported by the equipment) methods, as a rule, have low accuracy and inability to localize faults. The car's built-in diagnostics cannot affect the situation due to the small number of sensors in the steering system. The reasons for the low accuracy of the methods include design features, low availability of components (low maintainability). Difficulties in localization of malfunctions are caused by the structural scheme which is characterized by parallel - consecutive construction. The parameters of diagnostic methods are analyzed, the proposed method is based on the structure of the steering, in the implementation of which test effects are applied to the steered wheels. In total it is necessary to carry out three measurements of backlashes and as a result of mathematical processing of results it becomes possible to localize malfunction in three links of consecutive elements of the steering mechanism or a steering drive. In accordance with this approach, steering is considered as a set of three structures - parallel and two sequential. Rack and pinion steering was used as a model. Here, the parallel structure includes elements of the steering linkage: swing arm, left and right; steering rod, left and right; steering rack - left and right hinges. The sequential structure - left, includes a swing arm, left; steering rod, left; steering rack hinge, left; steering gear, steering shaft, steering wheel. Accordingly, the sequential structure of the right includes similar elements with the attribute "right". The structure of the steering play is considered in a similar way. As a result, it becomes possible to obtain a transformed system of three algebraic equations connecting clearances in three groups of mates and backlashes in parallel and two sequential steering structures. To measure the backlash, the turntables of the BOSCH FWA 4410 stand were used; in another version, the wheels were hung out. As a result of tests carried out on VW GOLF, VW PASSAT and RENAULT 25 vehicles with significant mileage, data was obtained indicating the need for technical interventions on localized groups of interfaces.

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.

Conflict and Sensitivity Analysis of Articulated Vehicle Lateral Stability Based on Single-Track Model

Lateral stability is quite essential for the vehicle. For the vehicle with an articulated steering system, the vehicle load and steering system performance is quite different from the passenger car with the Ackman steering system. To investigate the influence of the tire characteristics and vehicle parameters on lateral stability, a single-track dynamic model is established based on the vehicle dynamic theory. The accuracy of the built model is validated by the field test result. The investigated parameters include the tire cornering stiffness, vehicle load, wheelbase, and speed. Based on the snaking steering maneuver, the lateral stability criteria including the yaw rate, vehicle sideslip angle, tire sideslip angle, and lateral force are calculated and compared. The sensitivity analysis of the tire and vehicle parameters on the lateral stability indicators is initiated. The results demonstrated that the parameters that affect the lateral vehicle stability the most are the load on the rear part and the tire cornering stiffness. The findings also lay a foundation for the optimization of the vehicle’s lateral stability.

Optimal Design of the Six-Wheel Steering System with Multiple Steering Modes

Vehicles will face different working conditions during the use, and different working conditions have different requirements for vehicle functions, which results in many subdivided models. An off-road vehicle is a subdivision model produced to adapt to complex road conditions. In order to adapt to complex road conditions, vehicles should have a good passing ability, small size, and good flexibility. The six-wheeled vehicle has both good passing ability and small volume, which is the best choice for off-road vehicles. The design of the steering system becomes the key step to improve the flexibility of the six-wheeled vehicle. This paper mainly designs an independent steering system for a six-wheel electric vehicle with higher flexibility. The system is designed for six-wheel electric vehicles driven by six in-wheel motors. It mainly includes mechanical steering system and electronic control steering system. Both mechanical steering systems and electronic control steering system have multiple steering modes. Firstly, this paper introduces the various steering modes of the mechanical steering system and the electronic control steering system. Secondly, a CAD model is established by using the software Solidworks, and the system structure is introduced in detail combined with the CAD model. Finally, a kinematics model is established and calculated. The calculation results showed that the steering system can significantly improve the flexibility of the vehicle, so that the vehicle can complete the steering stably and quickly on complex road sections.

SIMULATION OF TROLLEBUS STEERING SYSTEM WITH ELECTRIC POWER STEERING BASED ON ROLLING ROTOR SWITCHED RELUCTANCE MOTOR

The analysis of power steering which used on modern rolling stock is carried out. Their main shortcomings are identified. Given the requirements for the steering of trolleybuses, a solution to increase its efficiency is proposed. Based on the developed mathematical model and functional diagrams of the trolleybus steering system with a electric power steering based on rolling rotor switched reluctance motor, a simulation model of trolleybus steering was created using the Matlab Simulink package. The peculiarity of the simulation model is taking into account the mass and size characteristics of the rolling stock, the parameters of the suspension of the steered axle, the impact of the road surface and the speed of the trolleybus, changes in the parameters of the electric motor magnetic system during operation. The rolling rotor switched reluctance motor which is offered for use as the electric power steering of the LAZ E183D1 trolleybus is calculated. The calculation of the magnetic system of the engine by the finite element method with the subsequent approximation of the obtained results is carried out. With the help of the developed simulation model the simulation of the trolleybus steering system with electric power steering based on rolling rotor switched reluctance motor was performed. Time diagrams of transients in the trolleybus steering system are obtained and their processing and analysis are carried out.

MATHEMATICAL JUSTIFICATION OF STABILITY OF STEERING BRIDGE OF WHEELED TRACTOR

The article deals with the influence of wheel oscillation and the micro-profile of the road surface on the stability of the wheel tractor axle movement. The reasons for the oscillations of the steered wheels, the design diagram of the controlled axle of the tractor and the sequence for determining the oscillation frequency of the axle of the tractor are presented. The reasons for the oscillation of the steered wheels are collisions with bumps, imbalance of the wheels and a double connection with the tractor frame through the steering system and the fastening of the steering axle beam. The most common functions for describing road irregularities that affect the movement of a tractor are the mathematical expectation and the average value of the ordinates of the micro-profile, the variance or standard deviation of the ordinates, the correlation function characterizing the relationship of various implementations of the micro-profile functions along the length of the road section and spectral density. Oscillations of the steered wheels have a side effect on the stability of the tractor, which leads to oscillations of the steered axle due to the presence of an additional degree of freedom (turning around the pivot) in comparison with uncontrolled ones. In addition, the steered wheels are interconnected by a steering linkage, which is damped due to clearances. Oscillations of the wheels can also occur due to the fact that the radial (normal) stiffness of the tires around the circumference is not the same. When such a tire rolls, the wheel begins to oscillate in a vertical plane. Such oscillations, performed due to changes in the parameters of the oscillatory system, are called parametric. Self-oscillations of the steered wheels cause significant dynamic loads on the steering parts, intense tire wear and lead to a loss of tractor controllability and driving stability. One of the main reasons for the occurrence of oscillations of the steered wheels is the presence of a gyroscopic relationship between the angular oscillations of the beam of the steered bridge in the transverse plane and the rotation of the wheels of this bridge relative to the pins. The article also discusses the physical essence of the processes occurring during self-oscillations of the tractor's controlled wheels.

Robust Control of EHCS of Intelligent Commercial Vehicle under Load Change

Electro Hydraulic Coupling Steering (EHCS) system is a new type of intelligent commercial vehicle steering system, having strong nonlinear characteristics. Besides, the change of load would cause the change of control system parameters, making not easy to establish an accurate control model of it. To realize the robustness of EHCS under the change of load, the controller based on the adaptive control method is proposed in this paper. To this end, the cosimulation model of EHCS is first established, where the constructed control model is simplified to a 2-degree-of-freedom model under reasonable simplification and assumption. Then, the steering angle controller is designed based on the model reference adaptive theory. Finally, some simulations are given to show the effectiveness of the proposed control method.