Steering Mode Research Articles

Research on the path planning integrated with multi-steer modes for heavy reconfigurable unit

Heavy reconfigurable units (HRUs) can form the heavy transportation vehicular platform (HTVP) to perform transportation for large equipment, by combining with each other. With all-wheel-independent-steered, the HRU can realize multi-steer modes (MSMs) such as Ackermann steer mode (ASM), diagonal steering mode (DSM), and zero radius steer mode (ZSM). However, with heavy weight and long wheelbase, the HRU’s mobility is poor if it only employs ASM. Therefore, this paper proposes a hierarchical path planning architecture, realizing path planning integrated with the above steer modes. This architecture includes the MSMs behaviors planning layer (upper layer) and smooth path planning layer (low layer). Firstly, this paper innovative proposes the MSM graph-based search algorithm in the upper layer, which extends nodes through graph-based searching on the grid map considering MSMs information. Then, the upper layer generates MSMs nodes sequence considering improved cost function for MSMs. Secondly, smooth path planning methods for the MSMs are respectively applied to the ASM sequence, DSM sequence, and ZSM sequence. Comparative simulations are shown as results based on measured parameters from real HRU. The results from the proposed method have the lowest or one of the lowest time cost compared with pure ASM planner and special steer modes planner used in the simulations. The maximum optimization rate can reach 10% or more.

Design and verification of a novel energy-efficient pump-valve primary-auxiliary electro-hydraulic steering system for multi-axle heavy vehicles

Multi-axle heavy vehicles employ a variable-length tie rod steering system to achieve precise multi-mode steering. However, the single-axle steering system need integrate two sets of electro-hydraulic control systems (EHCSs), resulting in the energy consumption significant increase. This paper proposes a novel energy-efficient pump-valve primary-auxiliary electro-hydraulic steering system (PVPA EHSS) which compose of a pump-controlled dual-steering cylinders primary system and a valve-controlled variable-length tie rod cylinder auxiliary system. The proposed system utilizes a single pump to drive both the primary and auxiliary EHCSs simultaneously, enabling high-precision and high-efficiency steering with multi steering modes. Additionally, to suppress the flow disturbance of the auxiliary system branch flow on the single-pump-controlled steering primary system, the interaction between the flow of the auxiliary system and the flow of the primary system in each steering phase is studied. A pump flow feedforward-angle feedback composite control strategy incorporating branch flow prediction is proposed to mitigate the disturbance and ensure the accurate steering of left and right tires. The experimental results demonstrate that compared to the traditional variable-length tie rod steering system, the proposed system reduces energy consumption by 58.66 %, and achieves precise adaptation of the left and right tire angles in multi steering modes.

Research on adaptive hydraulic drive optimization control of concrete mixing tank truck for open-pit mine.

The non-axisymmetric problem caused by the fluid sloshing in the tank of a mining concrete mixing tank truck during driving is affected by the excitation of complex road surfaces. The fluid sloshing is coupled with the dynamics of the vehicle body due to the excitation of the complex road surface. The traditional hydraulic drive proportional integral differential (PID) control method is not effective in dealing with such problems, which can easily lead to accidents such as overturning. To improve the accuracy and stability of the hydraulic drive control system, this paper proposes an optimized particle filter PID adaptive control method based on the elastic firefly (FA) algorithm to accelerate the convergence speed of control parameter optimization, and then analyzes its hydraulic drive control characteristics and structural applications, and discusses step steering and double lane change modes are simulated under filling rates of 1.5 and 2.0, respectively. The experimental results show that compared with traditional PID control, the proposed adaptive control method can significantly reduce the average speed error of hydraulic drive control to 0.03km/h and the maximum speed error to 0.17km/h. It also improves the control tracking performance and stability. The practicality of the adaptive hydraulic drive is verified in the filling rate experiments under step steering and double-lane shifting conditions. It has important reference value for the practical application of hydraulic drive control optimization of mining concrete mixing transport tank trucks.

Electromechanical processes in electric power steering system based on permanent magnet synchronous motor

Relevance. Electric power steering of vehicles successfully competes with hydraulic boosters of similar purposes, showing high efficiency, energy saving and environmental friendliness. Aim. To study and research electromechanical processes of electric power steering system based on permanent magnet synchronous motor. Methods. Mathematical and numerical modeling using the Matlab/Simulink software package. Results. The article discusses the operating modes of an electric power steering based on an electric motor with permanent magnets. The authors analyzed two classic schemes for constructing steering systems with electric power steering – with the electric motor placed on the steering column and on the steering rack. Block diagrams of the mechanical and electrical parts of the steering system have been developed. Based on mathematical dependencies characterizing the operating modes of the steering system, a complete dynamic simulation model of the electric power amplifier was obtained on the MATLAB/Simulink platform. Based on a preliminary analysis of control methods and algorithms in the system to solve the problem of control stability, PI controllers with low-pass filters are implemented to regulate the current and voltage of the electric motor depending on the speed of the vehicle and the angle of rotation of the steering wheels. The simulation results were used to design a real electric power steering for a specific vehicle. Conclusions. The complete simulation model of an electric booster based on a synchronous motor with permanent magnets in a car steering system obtained by the authors adequately reflects the dynamic control processes and can be used in the design of automotive vehicles.

Comparative Study of SFPE and Steering Modes in Pathfinder to Optimise Evacuation Routes

This paper investigates the possibilities of using an agent-based evacuation model to analyse the formation of queues at the exits of enclosed spaces and the evacuation process of people. The aim is to investigate how the density of people in a crowd affects the safe movement of people and how the width, number, and location of exits affect evacuation time. The analysis was carried out using the Pathfinder evacuation model, which provides two modes to simulate the movement of people: steering and SFPE. An enclosed space of 20 m × 30 m was investigated. First, the differences between the modes of the evacuation model to simulate the movement of people were compared. Then, the steering mode with limited door flow was set and the effect of the width, number, and location of the exits with a total width of 4 m on the evacuation time was investigated. The results of this study highlight differences in the simulation of the movement of people according to the different modes and provide valuable information for the design of safe escape routes. Proper design of escape routes can prevent an adverse situation that could arise when evacuating a large number of people.

24-GHz 4TX–4RX Phased Array Transceiver With Automatic Beam Steering Mode for FMCW Radar Applications

24-GHz 4TX–4RX Phased Array Transceiver With Automatic Beam Steering Mode for FMCW Radar Applications

Design and Experiment of an Agricultural Field Management Robot and Its Navigation Control System

The application of robotics has great implications for future food security, sustainable agricultural development, improving resource efficiency, reducing chemical pesticide use, reducing manual labor, and maximizing field output. Aiming at the problems of high labor intensity and labor shortage in the fields of pesticide application, weeding, and field information collection, a multifunctional and electric field management robot platform is designed, which has four switching steering modes (Ackermann steering, four-wheel steering, crab steering, and zero-radius steering), and its wheel-track can be automatically adjusted. Commonly used spraying booms, weeders, crop information collectors, and other devices can be easily installed on the robot platform. A multi-sensor integrated navigation system including a satellite positioning system, an RGB camera, and a multi-line lidar is designed to realize the unmanned driving of the robot platform in a complex field environment. Field tests have shown that the robot can follow the set route, and tests under simulated conditions have indicated that it can also dynamically correct paths based on crop rows by using a visual system. Results from multiple trials showed that the trajectory tracking accuracy meets the requirements of various field management operations.

A Versatile Control Method for Multi-Agricultural Machine Cooperative Steering Applicable to Two Steering Modes

This article aims to address the unnecessary stopping and low efficiency issues present in existing multi-machine cooperative steering control methods. To tackle this challenge, a novel cooperative control approach for multiple agricultural machines is proposed, considering two typical steering modes of farm machinery. This approach encompasses a multi-machine cooperative control framework suitable for both steering modes. Based on the established lateral and longitudinal kinematics models of the farm machines, the method includes a path-tracking controller designed using the pure pursuit and Stanley algorithms, a formation-keeping controller based on PID control, and a T-turn cooperative-steering controller based on a problem-solving approach. To assess the method’s viability, a collaborative simulation platform utilizing CarSim and Simulink was constructed, which conducted simulations for both U-turn and T-turn cooperative steering controls. The simulation results indicate that the proposed control framework and methodology can effectively ensure no collision risk during the U-turn and T-turn cooperative steering processes for three farm machines, eliminating stopping in T-turn, enhancing safety, and improving fuel economy. Compared with traditional sequential control methods, the proposed approach reduced operation time by 17.47 s and increased efficiency by 15.29% in the same scenarios.

Electric shovel trajectory tracking with inversion sliding mode based on Lyapunov functions

The harsh actual working environment and heavy weight of the electric shovel pose a great challenge to its trajectory tracking performance. Taking into account the strong robustness and anti-interference performance of the sliding mode control method and the global stability of the inversion control method, a Lyapunov-based inversion sliding mode trajectory tracking method is proposed in this paper, and its effectiveness is verified through numerical simulation based on the electromechanical coupling dynamic model of the electric shovel and the actual electric shovel tracking experiment. The results show that the trajectory tracking method can effectively realize the trajectory tracking of the electric shovel accompanied by tracking deviation within 0.3 m. The existence of the track slip phenomenon makes the electric shovel shake when steering, which also makes the actual operating velocity of the electric shovel fluctuate greatly. Meanwhile, the steering process of the electric shovel is accompanied by a regenerative braking steering mode.

Analysis and Experimental Investigation of Steering Kinematics of Driven Steering Crawler Harvester Chassis

In the context of automatic driving, the analysis of the steering motion characteristics is critical for enhancing the efficiency of crawler harvesters. To address issues such as the low transmission efficiency and the large steering radius encountered by traditional crawler harvesters featuring hydrostatic drives, a driven steering crawler harvester chassis was designed. This involved analysis of the chassis transmission system structure and its steering characteristics under several conditions, including differential steering, differential direction reversal, and unilateral braking steering. The steering parameters were determined based on real-time kinematic positioning–global navigation satellite system (RTK-GNSS) measurements, and they were compared with theoretical predictions based on the crawler harvester steering kinematics. The slip rates and modified models of the crawler chassis for various steering modes were then obtained. The results indicated that the increase in the ratio between the running input and steering input speeds led to larger track steering radii and smaller average rotational angular velocities. Remarkably, the slopes of the linear fits of the tracked chassis steering parameters varied significantly under differential direction reversal and differential steering modes. Compared with the actual results, the correlation coefficient of the tracked chassis steering parameters fitting model is close to 1. The steering parameter model was deemed suitable for actual operational requirements. The results provide a valuable reference for designing navigation and steering models of crawler harvesters operating on different road surfaces.

A Biomimetic Piezoelectric Composite‐Driven Undulation Underwater Robotic Structure: Characteristic Analysis and Experimental Investigation

Numerous proposals and recommendations have been made in the development of underwater undulation robots, but very few studies have focused on the undulation characteristics of undulation robots. The undulating mode of the clearnose skate utilizing the activation of the pectoral fins in undulatory bursts is particularly suitable for slow and efficient swimming. Inspired by the working principle of the clearnose skate, herein, an undulation robotic structure is presented. Considering the hydrodynamic skeleton and propulsion mechanism of the clearnose skate, the solution is based on a piezoelectric composite for realizing undulatory propulsion. This approach leverages the converse piezoelectric effect and modal coupling to produce the desired undulating motion, thereby achieving the undulation design of the robot. The proposed robotic structure can realize the propulsion mode using piezoelectric composites to undulate in the same direction and can use the clockwise or counterclockwise undulation of piezoelectric composites to achieve the steering mode. In addition, finite element analysis is employed as an approach to investigate the undulation characteristics and transient vibration characteristics of the robot. The operational efficiency of the robotic structure is assessed through experiments. The results show that the propulsion mode achieves the speed of 3.33 body‐length s−1. The steering mode exhibits the steering velocities of 17.4 deg s−1.

Research on Differential Steering Dynamics Control of Four-Wheel Independent Drive Electric Tractor

Traditional tractors can only achieve steering through mechanical structures such as steering knuckles and steering trapezoids. Among them, the mechanical structure is more complex, and various parts are easily damaged, making the tractor malfunction. The four-wheel independent drive differential steering mode differs from the traditional Ackermann steering mode, which realizes steering by controlling the inner and outer wheel torque, which can accurately steer the working state of high-end agricultural machinery equipment and improve the operating efficiency of agricultural machinery equipment. Aiming at the dynamic control problem in the steering of electric tractor four-wheel independent drive, a layered control strategy based on the sliding mode control of yaw torque at the upper level and the optimal torque distribution level based on the mean load rate of vehicle tires at the lower was proposed. By analyzing the differential steering mechanism of a four-wheel independent drive, a dynamic model of differential steering of the electric tractor is established, and a dynamic controller of a four-wheel independent drive is designed according to the layered control strategy. The upper controller tracks and controls the expected yaw speed on the basis of the sliding mode control to track the driver’s intention, and the lower controller realizes the optimal torque distribution based on the principle of the optimal average load rate of the vehicle tire to ensure the steering stability of the electric tractor. The effect of the controller was simulated and analyzed under typical conditions of double line shift, serpentine, and step. The results showed that the sliding mode controller is better than the PID controller in driver intention tracking. Compared with the average allocation strategy, the average maximum load rate of the vehicle tire under the three working conditions is reduced by 16.9%, 13.8%, and 17.3%, respectively, which proves the effectiveness of the layered control strategy. In the real car test, the sliding mode controller is better than the PID controller in the driver intention tracking. This study has important guiding significance for improving the maneuverability and stability of electric tractors.

Active steering of omni-droplets on slippery cross-scale arrays by bi-directional vibration

Directed droplet manipulation is paramount in various applications, including chemical micro-reaction and biomedical analysis. The existing strategies include some kinds of gradients (structure, inherent wettability, and charge density), whereas they suffer from several limitations, such as low velocity, limited volume range, poor durability, and inefficient environmental suitability. Moreover, active bi-directional reversal of omni-droplets remains challenging because one kind of microstructure at a single scale cannot acquire two kinds of net results of mechanical interaction. Herein, we report an active and directional steering of omni-droplets utilizing bi-directional (vertical and horizontal) vibration on slippery cross-scale structures consisting of macro millimeter-scale circular arc arrays and micro/nanometer-scale slant ratchet arrays, which are fabricated by femtosecond laser patterned oblique etching and lubricant infusion. The physical mechanism of active droplet steering lies in the relative competition between the forces under vertical and horizontal vibration, which mainly arise from the circular arc arrays and slant ratchet arrays, respectively. Various steering modes, including climbing and programmable manipulation, can be realized. Our work is applicable to a wide range of potential applications, including circuit on/off and droplet-based chemical micro-reaction, particularly in the field of high-throughput omni-droplets operation.

Magneto-mechanical therapeutic effects and associated cell death pathways of magnetic nanocomposites with distinct geometries.

Recent years have witnessed important developments in the emerging field of magneto-mechanical therapies. While such approaches have been demonstrated as a highly efficient route to augment, complement, or entirely replace other therapeutic strategies, important aspects are still poorly understood. Among these, the dependence between the cell death pathway and the geometry of magnetic nanocomposites enabling magneto-mechanical therapies under a low-frequency rotating magnetic field (RMF) is yet to be deciphered. To provide insights into this important problem, we evaluate the cell death pathway for two magnetic nanocomposites with highly distinct geometries: Zn0.2Fe2.8O4-PLGA magnetic nanospheres (MNSs) and Zn0.2Fe2.8O4-PLGA magnetic nanochains (MNCs). We show that under exposure to an RMF, the MNSs and the MNCs exhibit a corkscrewed circular propulsion mode and a steering propulsion mode, respectively. This distinct behavior, with important implications for the associated magneto-mechanical forces exerted by these nanomaterials on surrounding structures (e.g., the cellular membrane), depends on their specific geometries. Next, using numerical simulations and cell viability experiments, we demonstrate that the field strength of the RMF and the rotating speed of the MNSs or MNCs have strong implications for their magneto-mechanical therapeutic performance. Last, we reveal that the magneto-mechanical effects of MNSs are more prone to induce cell apoptosis, whereas those of the MNCs favor instead cell necrosis. Overall, this work enhances the current understanding of the dependences existing between the magneto-mechanical therapeutic effects of magnetic nanocomposites with different geometries and associated cell death pathways, paving the way for novel functionalization routes which could enable significantly enhanced cures and biomedical tools. STATEMENT OF SIGNIFICANCE.

Research on the Emergency Obstacle Avoidance Strategy of Intelligent Vehicles Based on a Safety Distance Model

Under emergency conditions, the safety distance between vehicles is insufficient, and drivers initiate unreasonable obstacle avoidance, which results in accident risks to vehicles. Therefore, an emergency obstacle avoidance system is needed for intervention to avoid traffic accidents. This paper proposes a coordinated steering and braking obstacle avoidance control strategy based on a safety distance model. The strategy takes into account handling stability and ride comfort. In the emergency braking obstacle avoidance module, the safety distance model and the graded warning mechanism based on the braking process are established. In the emergency steering obstacle avoidance module, a steering safety distance mode with multiple constraints is established, the obstacle avoidance trajectory is planned using the fifth-degree polynomial, and the obstacle avoidance trajectory is tracked using the model predictive control algorithm. The co-simulation results show that the emergency obstacle avoidance strategy proposed in this paper can select the appropriate way to complete obstacle avoidance under different working conditions. In braking obstacle avoidance, the braking deceleration essentially matches the expected value. In steering obstacle avoidance, the maximum error of lateral displacement can be reduced to 0.09 m. The research in this paper can provide a theoretical and practical basis for improving the driving safety, handling stability and ride comfort of intelligent vehicles.

Research on tyre mechanics model for multi-axle coordinated steering of heavy vehicles

Compared with passenger cars, heavy vehicles have larger loads, longer bodies, more steering modes, and are more likely to cause improper steering angle relationships among the wheels, resulting in uncoordinated steering. This uncoordinated steering makes the tyres roll and drag, which results in abnormal lateral and longitudinal slips, changing the lateral and longitudinal mechanical characteristics of tyres and leading to low path tracking accuracy and poor steering performance of vehicles. Therefore, a tyre model containing lateral and longitudinal mechanical characteristics under heavy load is the key to solving the problem of uncoordinated steering in heavy vehicles. Firstly, with the physical tyre model, the lateral and longitudinal slip is described as carcass deflections. With the carcass deflections and contact pressure distribution of heavy load, the tyre forces under uncoordinated steering conditions are derived. Then, the tyre imprint parameters are obtained with a test bench, and a two-dimensional contact pressure distribution model is established to reproduce the contact pressure distribution of tyre under heavy loads and dynamic slips. The comparison results with Magic Formula (MF) and Trucksim are generally consistent, proving the effectiveness of the model. Finally, a lateral and longitudinal tyre force distribution control of vehicles is carried out based on the established model. The results of the Trucksim-Simulink co-simulation show that the path tracking accuracy of vehicles is significantly improved, which demonstrates that the tyre model incorporating lateral and longitudinal mechanical characteristics under heavy loads can provide a theoretical basis for solving the problem of uncoordinated steering in heavy vehicles.

Design and Verification of Crab Steering System for High Clearance Self-Propelled Sprayer

A crab steering system aiming at improving the steering flexibility and operation efficiency of the high clearance sprayer was designed. First, a steering transmission mechanism of the high clearance sprayer was designed according to the operational and structural characteristics of the sprayer. Meanwhile, a crab steering hydraulic system based on load sensing was designed, and a mathematical model of the steering transmission mechanism and hydraulic system was established to describe the working characteristics of the crab steering system. On the basis of analyzing the operating environment of the sprayer and the operating characteristics of crab steering mode, a control strategy and algorithm of the crab steering system were proposed. The simulation model of the crab steering control system was built according to the established mathematical model, and the simulation analysis of the crab steering system was carried out. The simulation results showed that under the excitation of step signal, the average deviation of the two front wheels is 0.063°, and the absolute value of the maximum deviation is 2.75°, which is within the allowable range of deviation and meets the crab steering demand of the sprayer. Additionally, in order to verify the effectiveness of the designed system, an actual vehicle test platform of the crab steering system was built based on the 3WPG-3000 high clearance self-propelled sprayer independently developed by the research group, and the field test results revealed that the average deviation of the four wheels was 0.285°, the maximum absolute deviation was 2.587°, the rotation deviation was small, within the allowable and reasonable range. Altogether, the results of the simulation and field test verify the accuracy, stability and practicability of the crab steering system, which effectively improved the maneuverability of the sprayer.

Aerodynamic Analysis of Large Aspect Ratio Parafoil

Large aspect ratio parafoils are more attractive compared with moderate ones less than 3.5, since they either improves load-carrying capacity with the same aero-dynamical area or decreases taxing speed with the same load. Based on its original airfoil, one open-source elliptical parafoil with 4.7 AR is modified while scaling the canopy geometric parameters, then CFD simulations, solving the incompressible Reynolds time-averaged Navier-Stokes equation with the (SST) K-ω turbulence model in the finite volume method, are adopted to analyze its aerodynamics in forward taxing mode as well as steering mode with lateral wind. With the numerical simulation results of this canopy, lift and drag are analyzed according to their attack angle profiles for taxing. The steering mode with the deflection of one-side flap increases the drag coefficient significantly, even it raises its lift simultaneously, reduces the lift-drag ratio, and generate rolling and yaw moments; The rolling moment due to lateral wind during steering mode has two phases of rising linked by a short straight line when sideslip angle increases, while yaw moment increases to a peak value then reduces, finally followed by a relatively stable trend. Compared with the above two moments, the pitching moment changes moderately with the increase of the sideslip angle, although it has an overall decreasing trend; The simulation of the modified canopy provides a calculation basis for its following manufacture and dynamical modelling.

Parasitic Array Based Radiation Pattern Reconfigurable Patch Antenna for WLAN Application

This article presents a radiation pattern reconfigurable patch antenna using three rectangular parasitic elements for WLAN (5.8 GHz) application. A rectangular driven patch with two parasitic elements placed parallel to both non-radiating edges and the third parasitic element is located on the radiating edge of driven element. The parasitic elements located on non-radiating edges are loaded with shorting posts. The electrical connection between the post and ground plane is controlled by an RF PIN diode switch. Based on switching state (ON/OFF) of the PIN diodes, post loaded parasitic elements, switch their function between director and reflector to produce beam reconfiguration in the proposed antenna. For different switching combinations of the PIN diodes, beam steering directions in H-plane are obtained at 0˚, +50˚, –50˚ for E-plane radiation maximum at +30˚, while fourth beam steering angle is found at ±50˚ with corresponding E-plane radiation maximum at ±40˚. Measured peak gain of the proposed antenna varies between 3.46 dBi and 3.74 dBi for different beam steering modes. With measured resonant frequency around 5.85 GHz throughout the reconfiguration process, the proposed antenna is considered as a potential candidate for WLAN application.

A 1.2 V high‐speed low‐power preamplifier latch‐based comparator

The power consumption of chips has emerged as a major concern with the increased integration of analog circuitry. This work focuses on a two-stage comparator based on a preamplifier with latch for a successive approximation analog-to-digital converter. In order to minimize power loss and delay time, the charge steering approach was used in the design of latch as well as preamplifier. The suggested comparator is simulated in SMIC 0.18-um process in comparison to the comparator without charge steering mode. The results reveal that the average power consumption is only around 22 uW for varied input voltage at a supply voltage of 1.2 V, which is relatively lowered by approximately 30%. Meanwhile, delay time is also reduced by about 25%.