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- Suspension systems are vital in determining the vehicle's response to various driving conditions, including braking maneuvers. This paper aims to investigate the impact of suspension characteristics on braking performance, to improve overall driving safety and comfort. This study used a sedan car model that drives on a straight track and cornering. Modeling was carried out using the Altair Motion view 2021 with two test cases: braking tests on a straight track and brake-in-turn tests with speeds of 30 km/h and 60 km/h. The results showed that in braking tests on a straight track, increasing suspension stiffness reduces longitudinal slip on the rear wheels and suspension travel on both the front and rear wheels. This reduction in longitudinal slip results in the actual wheel speed value getting closer to the wheel rotational speed. While in the brake-in-turn test, increasing stiffness affects the lateral slip of the rear wheels. This improves driving safety because it reduces the potential for the car to skid. [ABSTRACT FROM AUTHOR]

Robotic evacuation process is commonly performed for confined spaces such as reactors and process towers of chemical, petrochemical, oil, and gas industries. This study deals with an applied research for amelioration of energy dissipation through robotic evacuation process of hazardous bulk materials with possibility of explosion as well as combustion inside industrial confined spaces. As a source of energy dissipation in the process was longitudinal slip of mobile robot wheels, a wheel slip control system was developed for the robot. The system was designed based on control algorithm of proportional integral and control strategy of increasing torque and speed of wheels. Effectiveness of the system for different levels of robot forward speed (0.5, 0.33 and 0.17 m/s) and tire air pressure (55.16, 34.47 and 20.68 kPa) was practically assessed through robotic trials on various solid ball diameters (0.0508, 0.0254 and 0.0127 m). Results obtained from the trials elucidated that employment of the wheel slip control system led to noteworthy amelioration of energy dissipation from range of 132.81–774.62 to 85.73–492.80 J/m2. It discloses that energy dissipation reduced 19.57–57.50%. Magnitude of energy dissipation reduction related to positive effect of causative factors (robot forward speed, tire air pressure, and solid ball diameter) on the slip of robot wheels. Among the causative factors, solid ball diameter had the greatest effect on magnitude of energy dissipation reduction. Overall, outcome of this research is helpful for energy dissipation management through robotic evacuation process of solid bulk materials. [ABSTRACT FROM AUTHOR]

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• Traction energy aspect of tractor-trailer wheeled robot has emerged in this research. • As robot drawbar pull increased, the traction energy indicators increased. • 5.77–33.78 % of traction energy consumption was wasted by the robot wheels. • Results are profitable for the wheeled robot in structured greenhouse environments. The novel purpose of this applied research is to gain insight into traction energy aspect of an autonomous wheeled robotic system for carrying, spraying, and harvesting tasks in the greenhouse environment. Traction energy indicators (traction energy consumption, traction energy dissipation, and drawbar pull energy) of a wheeled robot were ascertained as affected by operational variables of robot forward speed (0.17, 0.33 and 0.5 m/s), payload weight (1, 2, 3, 4 and 5 kN) and tire air pressure (20.68, 34.47 and 55.16 kPa). Analytical results clarified that meaningful contribution of robot forward speed to the traction energy indicators was marginal (<40 times) in comparison with that of payload weight. This indicated that adjustment of payload weight should be considered as first priority for performance optimization of the robotic system. Meanwhile, modeling results described that the combinatorial effect of payload weight and robot forward speed on traction energy indicators was synergetic. This disclosed linear increasing dependency of traction energy consumption (145–19-873.41 J/m2), traction energy dissipation (9.01–292.85 J/m2), and drawbar pull energy (140.17–864.85 J/m2) on concurrent increment of payload weight and robot forward speed. The aforementioned amplitudes divulge that 5.77–33.78 % of traction energy consumption was dissipated by wheels of the robotic system. Overall, these results are profitable for energy-efficient design and performance optimization of tractor-trailer wheeled robot which is not only working in the greenhouse environment, but also employing in any structured environment with concrete flat surface. [ABSTRACT FROM AUTHOR]

In recent years, there is a worldwide growing interest in using concrete mixes with recycled concrete aggregates (RCA). Reinforced concrete is the composite of concrete and steel rebars, where the rebars provide relatively higher tensile strength and ductility, energy absorption capacity, and crack control. This composite action depends on the interfacial bond between the rebar and the concrete. The bond behavior is commonly evaluated from pull-out test results which yield the global relationship between the average bond-stress and the corresponding slip and depend on the concrete properties and the rebar geometry. The present study investigates the bond behavior in concrete with RCA in comparison to concrete with natural aggregates aiming at short bond lengths to obtain the local bond-slip behavior. Two major complementary aspects of the bond behavior in the longitudinal (bond stress-slip) and circumferential directions (circumferential strain-slip) are studied, and the post-test interior damage is investigated. The study found that the magnitudes of the maximum bond stress are not affected by the aggregate type and are in accordance with the concrete compressive strength, but different internal damage mechanisms develop in the specimens of the two aggregate types. The different internal damage mechanisms in RCA specimens affect the internal confinement level's development and the circumferential strains' magnitude, which are considerably different than in concrete with natural aggregates.

China's Mars rover Zhurong successfully landed on Mars on 15 May 2021, and it is currently conducting an exploration mission on the Red Planet. This paper develops slip estimation models for the Mars rover Zhurong based on the data drive approach. Data were obtained by Zhurong's validator ground indoor tests, and the test site was equipped with a low-gravity simulation device and simulated Mars soil to simulate the Mars conditions as much as possible. The obtained slip models trained by BP and GA-BP algorithms were applied to estimate Zhurong's longitudinal (slip_x) and lateral slip (slip_y) on Mars, and the slip estimation values were used to display Zhurong's actual driving path. The analyzed results prove that the GA-BP slip models perform better than the BP models, and can both be applied for correcting Zhurong's path. The proposed models have high potential in guiding the path planning and monitoring of the slip for the Mars rover Zhurong. [ABSTRACT FROM AUTHOR]

Monitoring the rover slip is important; however, a certain level of estimation uncertainty is inevitable. In this paper, we establish slip estimation models for China’s Mars rover, Zhurong, using Gaussian process regression (GPR). The model was able to predict not only the average value of the longitudinal (slip_x) and lateral slip (slip_y), but also the maximum possible value that slip_x and slip_y could reach. The training data were collected on two simulated soils, TYII-2 and JLU Mars-2, and the GA-BP algorithm was applied as a comparison. The analysis results demonstrated that the soil type and dataset source had a direct impact on the applicability of the slip model on Mars conditions. The properties of the Martian soil near the Zhurong landing site were closer to the JLU Mars-2 simulated soil. The proposed GPR model had high estimation accuracy and estimation potential in slip value, and a 95% confidence interval that the rover could reach during motion. This work was part of a research effort aimed at ensuring the safety of Zhurong. The slip value may be used in subsequent path tracking research, and the slip confidence interval will be able to help guide path planning.

China’s Mars rover Zhurong successfully landed on Mars on 15 May 2021, and it is currently conducting an exploration mission on the Red Planet. This paper develops slip estimation models for the Mars rover Zhurong based on the data drive approach. Data were obtained by Zhurong’s validator ground indoor tests, and the test site was equipped with a low-gravity simulation device and simulated Mars soil to simulate the Mars conditions as much as possible. The obtained slip models trained by BP and GA-BP algorithms were applied to estimate Zhurong’s longitudinal (slip_x) and lateral slip (slip_y) on Mars, and the slip estimation values were used to display Zhurong’s actual driving path. The analyzed results prove that the GA-BP slip models perform better than the BP models, and can both be applied for correcting Zhurong’s path. The proposed models have high potential in guiding the path planning and monitoring of the slip for the Mars rover Zhurong.

We present a double-layered control algorithm to plan the local trajectory for automated trucks equipped with four hub motors. The main layer of the proposed control algorithm consists of a main layer nonlinear model predictive control (MLN-MPC) controller and a secondary layer nonlinear MPC (SLN-MPC) controller. The MLN-MPC controller is applied to plan a dynamically feasible trajectory, and the SLN-MPC controller is designed to limit the longitudinal slip of wheels within a stable zone to avoid the tire excessively slipping during traction. Overall, this is a closed-loop control system. Under the off-line co-simulation environments of AMESim, Simulink, dSPACE, and TruckSim, a dynamically feasible trajectory with collision avoidance operation can be generated using the proposed method, and the longitudinal wheel slip can be constrained within a stable zone so that the driving safety of the truck can be ensured under uncertain road surface conditions. In addition, the stability and robustness of the method are verified by adding a driver model to evaluate the application in the real world. Furthermore, simulation results show that there is lower computational cost compared with the conventional PID-based control method. [ABSTRACT FROM AUTHOR]

Steel-concrete composite slabs generally fail due to the debonding with separation of sections caused by longitudinal shear forces, regardless of the shape of the sheeting profile or the design of the embossments. This article presents an innovative full-connection bonding technology, consisting of producing bands of many small crown-shaped cuttings in the profile webs as a replacement for the embossments. The new technology has been tested on three commercial sheeting profiles. The results of the investigation show that full connection is achieved with the new system, i.e., yielding of both materials occurs without any slip, in contrast to the partial connection of traditional embossments. The longitudinal shear strengths are 1.4–7 times higher. The specimens tested include the use of conventional galvanized steel and concrete, as well as ferritic stainless steel and lightweight aggregate concrete. [ABSTRACT FROM AUTHOR]

Measurement of tyre longitudinal slip-ratio is often estimated from three independent measurements devices namely wheel rotation speed, vehicle speed and tyre rolling radius. This produces an expensive measurement system to indirectly determine the slip-ratio. This paper presents a method by which the slip-ratio is determined from a video camera using digital image correlation techniques. The camera, mounted in such a way that the contact patch region is captured, enables the system to measure the tyre tread speed and ground speed at the contact patch. The slip-ratio is then determined from these two measurements. [ABSTRACT FROM AUTHOR]

Reinforced concrete (RC) beams strengthened with bolted steel plates on their side faces are known as bolted side-plated (BSP) beams. The performance of BSP beams is closely related to the longitudinal partial interaction caused by the longitudinal slip on the plate-RC interface. In this study, an analytical model for the longitudinal slip and partial interaction was developed, and formulas for the BSP beams under several simple loading conditions were developed. The superposition principle was also proven applicable to the analysis of longitudinal slip, thus can be used to analyse the BSP beams under complicated loading conditions. The results of a previous numerical study were extracted to validate the analytical model, and an example was then presented to illustrate the applicability of the theoretical approach. This study enhances the understanding of the behaviour of BSP beams, and provides an approach to consider the influence of longitudinal partial interaction in the BSP strengthening design. [ABSTRACT FROM AUTHOR]

Monitoring the rover slip is important; however, a certain level of estimation uncertainty is inevitable. In this paper, we establish slip estimation models for China's Mars rover, Zhurong, using Gaussian process regression (GPR). The model was able to predict not only the average value of the longitudinal (slip_x) and lateral slip (slip_y), but also the maximum possible value that slip_x and slip_y could reach. The training data were collected on two simulated soils, TYII-2 and JLU Mars-2, and the GA-BP algorithm was applied as a comparison. The analysis results demonstrated that the soil type and dataset source had a direct impact on the applicability of the slip model on Mars conditions. The properties of the Martian soil near the Zhurong landing site were closer to the JLU Mars-2 simulated soil. The proposed GPR model had high estimation accuracy and estimation potential in slip value, and a 95% confidence interval that the rover could reach during motion. This work was part of a research effort aimed at ensuring the safety of Zhurong. The slip value may be used in subsequent path tracking research, and the slip confidence interval will be able to help guide path planning. [ABSTRACT FROM AUTHOR]

Abstract: A new finite element model for steel–concrete side-plated beams exposed to mechanical and thermal loading is presented. The moisture and heat transfer through concrete is considered independent on mechanical deformations. The hygro-thermo-mechanical analysis is performed in two separate steps starting with the moisture and heat transfer analysis and continuing with the mechanical stress–strain analysis. The finite-element model of Davie, Pearce, and Bićanić was implemented for the moisture and heat transfer analysis in the concrete part of the beam. The Fourier equation of heat transfer for non-porous solids was applied in the steel part. A novel, strain-based finite-element formulation of the planar beam is proposed to perform the mechanical part of the fire analysis. Each of the two steps of the model is first verified by comparing the present numerical results with the experimental and numerical data available in the literature. The finite-element formulations of both the hygro-thermal and the mechanical steps of the analysis are found to be reliable and accurate. Finally, effects of the side reinforcing of a RC beam as one of the methods of structural retrofitting are explored in the case of a typical fire scenario and an important contribution of the side-plates to the ultimate fire resistance of the beam is discovered, particularly when higher levels of the service load are applied to the beam. [Copyright &y& Elsevier]

Existing reinforced concrete (RC) beams can be effectively strengthened by attaching steel plates to the side faces of the beams using anchor bolts. The performance of this type of beam, bolted side-plated (BSP) beams, is mainly controlled by the degree of partial interaction at the steel-concrete interface. In this study, a total of seven moderately reinforced BSP beams with different steel plate depths and various bolt spacings were tested. Their behaviours were compared to the available test results for lightly reinforced BSP beams obtained by other researchers. The results show that moderately reinforced RC beams are more effective in increasing the flexural strength and ductility capacity using deeper steel plates than the use of a greater number of anchor bolts. It was also found that the longitudinal and transverse slips were controlled by both the stiffness ratios of the steel plates to the RC beam and the force-slip response of the anchor bolts. [ABSTRACT FROM AUTHOR]

Tyre–soil interaction models were developed for the investigation of tyre dynamic behaviours with two different approaches: finite element method and analytical method. In the finite element model the 3D tyre was modelled as a non-linear solid assembly consisting of tread block, belt and carcass layers, sidewall, beads and rim, and the soil modelled as a 3D object was attributed with the elasto-plastic mechanical behaviour. In the analytical model the contact between deformable tyre and soft soil is described by non-linear springs and dampers in the radial direction and shear stress-displacement model in the tangential direction. The equations accounting for the analytical model were integrated in the multi-body simulation software-ADAMS. Simulations with these two different tyre–soil interaction models were carried out to study the longitudinal slip-longitudinal force and slip angle-lateral force relationship. [ABSTRACT FROM AUTHOR]

Abstract: As longitudinal slip affects vehicle–pavement interactions on roads and hard surfaces, so too does it play an important role in interactions between vehicles and soft terrains, including snow. Although many slip-based models have been developed recently for tire–snow interactions (e.g., [1] and references cited therein), these models have only been partially validated, due to a lack of relevant experimental data. This paper presents comprehensive data from tests that were performed using a newly-developed test vehicle traversing natural snowy terrain, over a wide range of values for longitudinal slip, vertical load and torque via an effective accelerate/brake maneuver. Drawbar pull, motion resistance, wheel states and tire stiffness were presented as a function of slip; tire sinkage was obtained using a laser profilometer; strength and depth of snow were found using a snow micropenetrometer. The effects of the rear tire going over snow compacted by the front tire were also studied. The maximum traction force normalized by the vertical load is found to be ≈0.47, maximum motion resistance normalized by the vertical load is ≈0.4. Comparison of the trend and order-of-magnitude of test results with those from existing slip-based numerical model [1] shows good comparison in motion resistance, tire sinkage, and longitudinal stiffness, but indicates that a better traction model is needed to improve the comparison. [Copyright &y& Elsevier]

In a dynamic vehicle simulation, longitudinal tire force is primarily based on the longitudinal slip (ratio). In the longitudinal slip formula, state variables are used in the denominator. This causes a divergence problem for numerical simulations of vehicle dynamics. To avoid this numerical singularity, a differential slip calculation method was developed for use in dynamic vehicle simulations. However, this method also causes a singularity when the wheel velocity approaches zero in a pure slip state, such as during sudden braking. In this paper, a new longitudinal slip calculation method, which can overcome singularities in all velocity conditions, is proposed. For this purpose, the Taylor series is adapted to the slip formula and the idea of virtual wheel rotation stiffness is introduced for the development of the slip equation. The physical phenomenon at the zero slip state is analyzed. Finally, the proposed slip formula is used to solve the numerical singularity problem, and the non-singular slip (NSS) calculation method is proposed. The proposed NSS method is applied to tire model performance test (TMPT) simulations to validate its performance. [ABSTRACT FROM AUTHOR]

Abstract: The problem of modeling vehicle longitudinal motion is addressed for front wheel propelled vehicles. The chassis dynamics are modeled using relevant fundamental laws taking into account aerodynamic effects and road slop variation. The longitudinal slip, resulting from tire deformation, is captured through Kiencke''s model. A highly nonlinear model is thus obtained and based upon in vehicle longitudinal motion simulation. A simpler, but nevertheless accurate, version of that model proves to be useful in vehicle longitudinal control. For security and comfort purpose, the vehicle speed must be tightly regulated, both in acceleration and deceleration modes, despite unpredictable changes in aerodynamics efforts and road slop. To this end, a nonlinear controller is developed using the Lyapunov design technique and formally shown to meet its objectives i.e. perfect chassis and wheel speed regulation. [Copyright &y& Elsevier]

Abstract: Significant challenges exist in the prediction of interaction forces generated from the interface between pneumatic tires and snow-covered terrains due to the highly non-linear nature of the properties of flexible tires, deformable snow cover and the contact mechanics at the interface of tire and snow. Operational conditions of tire–snow interaction are affected by many factors, especially interfacial slips, including longitudinal slip during braking or driving, lateral slip (slip angle) due to turning, and combined slip (longitudinal and lateral slips) due to brake-and-turn and drive-and-turn maneuvers, normal load applied on the wheel, friction coefficient at the interface and snow depth. This paper presents comprehensive three-dimensional finite element simulations of tire–snow interaction for low-strength snow under the full-range of controlled longitudinal and lateral slips for three vertical loads to gain significant mechanistic insight. The pneumatic tire was modeled using elastic, viscoelastic and hyperelastic material models; the snow was modeled using the modified Drucker–Prager Cap material model (MDPC). The traction, motion resistance, drawbar pull, tire sinkage, tire deflection, snow density, contact pressure and contact shear stresses were obtained as a function of longitudinal slip and lateral slip. Wheel states – braked, towed, driven, self-propelled, and driving – have been identified and serve as key classifiers of discernable patterns in tire–snow interaction such as zones of contact shear stresses. The predicted results can be applied to analytical deterministic and stochastic modeling of tire–snow interaction. [Copyright &y& Elsevier]

The dynamic behavior of any road vehicle is mainly influenced by the dynamic properties of tyres, which are the primary forces and moments. These force and moment characteristics are non-linear functions of a large number of parameters. In this paper, analytical predictive models developed in order to describe the forces and moments between the tyre and road. New tyre models are developed based on different normal pressure distributions with elliptical contact patch and also consider the existing tyre models. Equations to calculate tyre longitudinal force, lateral force characteristics for new tyre models and aligning torque, overturning moment characteristics for all tyre models are derived. Results for new tyre models show good agreement with the existing literature tyre models. Unsymmetrical trapezoidal normal pressure distribution with elliptical contact patch model gives better performance than other tyre models by considering all forces and moments. [ABSTRACT FROM AUTHOR]

Abstract: The aim is to understand the steel–concrete slip mechanisms and its dependence on geometrical and physical parameters, in order to improve designs for steel decking for composite slabs. A new methodology to build 3D non-linear FEM models has been developed to simulate the longitudinal slip mechanics of composite slabs in “pull-out” tests. Sensibility of shear resistance is analysed in relation to: friction coefficient, embossing depth and slope, sheet thickness, inclination, length, width and spacing of embossments and profiling angle of rib shape. A new steel sheet design has been developed and optimised. On the other hand, several pull-out tests as well as reduced “m–k” shear-bond bending tests have been carried out in order to corroborate and validate FEM results, as well as to evaluate some other aspects. This paper summarizes the conclusions regarding to design recommendations and general slip behaviour matters. Several parameters, such as the embossing slope, the retention angle, the surface friction conditions, etc., have shown to be very significant in slip resistance. [Copyright &y& Elsevier]

• Study is spearhead for tractor energy dissipation in wheel-soil interface. • Energy dissipation was approximately equal to quarter of energy expenditure. • As draft force augmented, portion of energy dissipation due to wheel slip raised. • As draft force ascended, the portion due to rolling resistance force dropped. • Among causative variables, plowing depth dictated energy dissipation magnitude. Inevitable interaction between soil and pneumatic tires of an off road vehicle in a rectilinear motion leads to experience of energy dissipation. Rolling resistance force and longitudinal slip of wheels are responsible for the energy dissipation inside wheel-soil interface. Attention of current study is paid to methodically elucidate the energy dissipation by wheels of front wheel assist tractor for the period of plowing works. To achieve this goal, the energy dissipation dependency on draft force requirement of plow implement as well as tractor drive mode (rear wheel drive (RWD) and front wheel-assisted drive (FWAD)) was quantitatively ascertained. Results disclosed that the energy dissipation ascended in domain of 3.18-17.66 and 3.14-21.04 MJ/ha for the RWD and FWAD mode, respectively, as the draft force requirement proliferated from 3.85 to 23.04 kN. Whilst, energy expenditure for plowing works ranged from 12.45 to 74.85 MJ/ha. It means that the energy dissipation was approximately equal to quarter of energy expenditure for plowing works. When the draft force requirement augmented, portion of the energy dissipation caused by the slip of the wheels raised in range of 12.15-82.51% and thereby, that of rolling resistance force of the wheels dropped in range of 87.85-17.49%. Hence, to reduce the energy dissipation, for both drive modes at the higher draft force requirement, activation of slip control system for preservation of the slip of the wheels in a particular range is sufficient enough. For both drive modes at the lower draft force requirement, not only activation of the system, but also decrement of rolling resistance force of the wheels by overinflating the tires must be prescribed. In case of the FWAD mode, overinflating the tires must be accomplished based on generation of driving lead of front wheels in allowable range. [ABSTRACT FROM AUTHOR]

The problem of controlling the longitudinal motion of front-wheels electric vehicle (EV) is considered making the focus on the case where a single dc motor is used for both front wheels. Chassis dynamics are modelled applying relevant fundamental laws taking into account the aerodynamic effects and the road slope variation. The longitudinal slip, resulting from tire deformation, is captured through Kiencke's model. Despite its highly nonlinear nature the complete model proves to be utilizable in longitudinal control design. The control objective is to achieve a satisfactory vehicle speed regulation in acceleration/deceleration stages, despite wind speed and other parameters uncertainty. An adaptive controller is developed using the backstepping design technique. The obtained adaptive controller is shown to meet its objectives in presence of the changing aerodynamics efforts and road slope.