Pedal Travel Research Articles

Mechanistic Modeling of Hydraulic Energy Transmission Technology of an Improved Dental Patient Chair Design

This work focused on mechanistic modeling of hydraulic technology of an improved dental chair design. ISO 6385 standard for P(M)95 patient were basis for system parameters, and fathom masses between 60kg-93kg, corresponding to DINED 2003 mass of patients, produced total load on the pantograph. The force exerted by the lower limb of the dentist is an ergonomic stressor that was experimentally studied using Pascal’s law of the hydraulic system. Methodology adopted was mechanistic modeling technique. The results indicated that pedal force of 0.1375kN elevated trimmed chair (dead load) of 0.55kN, while pedal force of 211N to 277N were required to recline between 60kg-93kg masses on the system. It infers that the pump has a mechanical advantage of approximately 5, with displacement volume, 11.7825cm-2, that produced a platform displacement of 3. 75cm during a 15cm hydraulic pedal travel stroke. The experimental results corroborated Pascal’s laws and is has technological significance on carrier-long musculoskeletal disorders (MSDs) of lower limb among dental practitioners.

Research on Electric Vehicle Braking Intention Recognition Based on Sample Entropy and Probabilistic Neural Network

The accurate identification of a driver’s braking intention is crucial to the formulation of regenerative braking control strategies for electric vehicles. In this paper, a braking intention recognition model based on the sample entropy of the braking signal and a probabilistic neural network (PNN) is proposed to achieve the accurate recognition of different braking intentions. Firstly, the brake pedal travel signal is decomposed to extract the effective components via variational modal decomposition (VMD); then, the features of the decomposed signal are extracted using sample entropy to obtain the multidimensional feature vector of the braking signal; finally, the sparrow search algorithm (SSA) and probabilistic neural network are combined to optimize the smoothing factor with the sparrow search algorithm and the cross-entropy loss function as the fitness function to establish a braking intention recognition model. The experimental validation results show that combining the sample entropy features of the braking signal with the probabilistic neural network can effectively identify the braking intention, and the SSA-PNN algorithm has higher recognition accuracy compared with the traditional machine learning algorithm.

Single-Wheel Failure Stability Control for Vehicle Equipped with Brake-by-Wire System

In order to solve the problem of vehicle stability control after a single-wheel brake failure in the brake-by-wire system, a control strategy of braking force redistribution with a yaw moment is proposed to ensure the braking efficiency and stability of vehicles. In this strategy, a two-layer architecture is adopted. In the upper layer control, a fault factor is introduced to represent the real-time failure degree of the wheel, and the driver’s braking intention is perceived through the pedal travel and pedal speed of the driver. The braking force redistribution algorithm of the remaining three wheels is designed based on the wheel failure degree and braking intensity. In the lower control, according to the state parameters of the vehicle, the additional yaw moment, which controls the yaw rate and the sideslip angle of the vehicle, is calculated by using the sliding mode control theory, and the yaw moment is reasonably allocated to the normal wheel. By using MATLAB/Simulink and Carsim co-simulation, different braking strength and failure types are selected for simulation analysis. The simulation results show that the proposed control strategy can improve the braking efficiency and stability of the vehicle under different braking conditions.

A Regenerative Braking Control Strategy for ICVs Considering the Coupling Effect of Driving Conditions and Driving Styles

Regenerative braking is an important part of automotive energy-saving technology. Under different driving conditions and driving styles, the rules of the driver stepping on the accelerator pedal are different, which makes the regenerative braking intensity vary greatly. Different intensity of energy recovery is carried out under different driving conditions and driving styles, which is conducive to improving the efficiency of energy recovery. Therefore, we propose a regenerative braking control strategy (RBCS) based on an accelerator pedal for intelligent connected vehicles (ICVs) considering the coupling effect of driving conditions and driving styles. Firstly, a modified method of driving style characteristic parameters considering the influence of driving conditions is proposed. Secondly, α、β and γ are defined as accelerator pedal travel, driving condition and driving style correction coefficient respectively. The regenerative braking control strategy based on an accelerator pedal is established, which corrects the regenerative braking intensity according to correction coefficients. Thirdly, the driving data are obtained through the driver-in-the-loop experiment. On this basis, the characteristic parameters of driving style are modified, and the values of α、β and γ are determined. Finally, the vehicle simulation model and hardware-in-the-loop experiment platform are established to verify the RBCS. The results show that the economy of the vehicle is further improved.

Progressing Brake Systems Improving Brake Feel Response Through Linear Electromagnetic Driver Utilization

This research focuses on improving the braking systems of vehicles by incorporating a brake feel feedback generation mechanism. The system includes a hydraulic brake unit, brake pedal, pedal travel sensor, control unit, and brake feel feedback generate unit. The pedal travel sensor captures movement state information when the brake pedal is pressed. The brake feel feedback generate unit utilizes a linear electromagnetic driver to generate resistance, mimicking the sensation of brake pedal operation, which is applied directly or indirectly to the pedal. The control unit generates drive signals for the linear electromagnetic driver based on the brake pedal's movement state information. This research aims to provide an effective and advantageous method of achieving brake feel feedback when braking is required.

Research on a novel electro-hydraulic brake system and pedal feel control strategy

The existing electro-hydraulic brake system does not consider the adverse effect of the failure of the brake pedal feel simulator on the function of the braking system and the driving safety of the vehicle. To solve the above problems, a novel electro-hydraulic brake system is proposed. Firstly, the structural scheme and the working modes of the system are analyzed, and the electro-hydraulic brake system model is established, and a control strategy for the controlling of the wheel cylinder pressure is put forward. Then, the pedal feel control strategy is studied, which can simulate arbitrary pedal characteristics by controlling the output torque of the motor. Moreover, for the failure of the pedal travel sensor, a pedal displacement estimation method is proposed based on the pressure sensor information of the front chamber of the master cylinder. And for the failure of the pedal feel simulation motor, the pressure of the front chamber of the master cylinder is controlled by adjusting the opening of the pedal feel simulation valve to realize the simulation of the pedal feel. The simulation results based on CarSim/AMESim/Simulink show that the proposed electro-hydraulic brake system has fast pressure response speed and quick pressure tracking accuracy. The pedal characteristics are essentially unchanged before and after the failure of the pedal feel simulation motor or the pedal travel sensor.

Bilateral cataract surgery improves neurologic brake reaction time and stopping distance in elderly drivers.

AimsTo determine brake reaction times before and after bilateral cataract surgery in elderly drivers.MethodsSixty‐four patients were evaluated on the day of and 4 weeks after bilateral cataract surgery. Forty‐three healthy individuals with a valid driving licence served as the control group. A driving simulator was used to determine brake reaction times after receiving a visual stimulus. Total brake reaction time (BRT) as well as neurologic reaction time (NRT), foot transfer time (FTT) and brake pedal travel time (BPTT) were measured, and the measurements obtained before and after cataract surgery were compared. The correlations between NRT, best‐corrected visual acuity (BCVA) and contrast sensitivity (CS) were assessed.ResultsOut of the 64 patients with bilateral cataract, 53 were assessed for postsurgical measurements. All time measures improved significantly after cataract surgery (BRT, 815.7(224) versus 647.9(148) ms; NRT, 364.7(91) versus 283.5(44) ms; FTT, 290.8(62) versus 248.6(58) ms; and BPTT, 160.6(96) versus 116.6(72) ms, p < 0.001). The calculated stopping distance improved significantly after surgery (22.3(6) versus 19.9(4) m at 50 km/h). Best‐corrected visual acuity (BCVA) and contrast sensitivity (CS) improved significantly after surgery (0.25(0.2) versus 0.05(0.05), n = 53, p < 0.001; 1.4(0.2) versus 1.6(0.1), p < 0.001, respectively). There was a significant negative correlation between CS and NRT before surgery (r = −0.253, n = 64, p = 0.04, Pearson’s correlation).ConclusionOur findings show a significant effect of CS on neurological BRTs and the corresponding stopping distances. This highlights the importance of presurgical CS evaluation as a critical factor in cataract surgery decisions in elderly drivers.

Modeling human-like longitudinal driver model for intelligent vehicles based on reinforcement learning

The driver model is the decision-making and control center of intelligent vehicle. In order to improve the adaptability of intelligent vehicles under complex driving conditions, and simulate the manipulation characteristics of the skilled driver under the driver-vehicle-road closed-loop system, a kind of human-like longitudinal driver model for intelligent vehicles based on reinforcement learning is proposed. This paper builds the lateral driver model for intelligent vehicles based on optimal preview control theory. Then, the control correction link of longitudinal driver model is established to calculate the throttle opening or brake pedal travel for the desired longitudinal acceleration. Moreover, the reinforcement learning agents for longitudinal driver model is parallel trained by comprehensive evaluation index and skilled driver data. Lastly, training performance and scenarios verification between the simulation experiment and the real car test are performed to verify the effectiveness of the reinforcement learning based longitudinal driver model. The results show that the proposed human-like longitudinal driver model based on reinforcement learning can help intelligent vehicles effectively imitate the speed control behavior of the skilled driver in various path-following scenarios.

Prediction of hyperelastic material sealing pressure using experimental and numerical analyses

In commercial vehicle air braking system, leakage is one of the major problems and will affect the performance of the vehicle braking in terms of brake pedal travel and stopping distance. If there is any leakage in the brake system, the vehicle stopping distance will not meet the safety regulations. One of the main reasons for braking system leakage is ineffective sealing mechanism. The majority of sealing elements used in the air brake system are O-rings, lip seals, and gaskets. This article presents an experimental procedure for measuring the sealing pressure between an O-Ring and its mating parts. The contact pressure measurement was performed in a static condition by means of an experimental test rig using Fuji film. For the sealing pressure study, a test rig was properly designed to replicate the actual operating conditions. Contact pressure was evaluated by means of Fuji film interposed between the O-ring and its mating parts. The sealing pressure tests were carried out for different clamping load conditions. The experimental results were compared with the numerical result using the finite-element analysis (FEA). A good correlation was found between the experimental and the numerical results. The outcome from the experimental results will be useful for finalizing the hyperelastic material models, which are input to the FEA for future reference.

Design of Adapting Multi-Servo Concept with Optimal Change in Tractor Brakes

All of the agricultural tractors are weighed down by heavy cargo loads &amp; ploughing so safety and efficient reliability is utmost important. Now-a-days tractors are conventionally having brakes which are being actuated by Mechanical linkages which is dominantly having several mechanical load distribution losses. This mechanical actuating stuff is going to get replaced by hydraulic actuation which will meet the reduction of increasing losses considerably.This paper introduces a conceptual illustration of adopting multi servo effect in traditional tractor brakes where the servo effect is present under optimal manner in dry tractor brakes. Also application of hydraulic actuation reflects a considerable reduction in pedal effort and travel which is the major mechanical advantage that can be attained. Thus, this article shows a conceptual analysis of increased braking efficiency by two variant packages: 1) Multi-Servo effect and 2) hydraulic actuation.

Analysis on Multi Linkage Brake System with Variable Pedal Ratio

The present paper aims atthe generation of the variable braking force without using any type of external assistance in brake assembly to get the effective braking system in a vehicle and to slow down it or to bring it to complete rest in the shortest time period.An optimized model was designed and it has been tested under different conditions by comparing the deformation plots and the standard stress plots effectively. Analysis was done for both the Normal and Panic conditions and the safety of the design was verified.According to the braking system designed, the braking effort that applied on the pedal isdynamically reduced with the help of the variable pedal ratio. When the pressure applied on the pedal, the pedal ratio gets increased which leads to the gradual increase of output force for the same amount of applied input force. The pedal ratio is dynamically increased in the panic situations for the better emergency braking. The length of the brake pedal is increased to get high pedal ratio which helps in attaining good efficacy and to overcome problems like long pedal travel, poor brake feel and to generate a variable braking force. We have come up with a simple, multi linkage design of brake pedal which will also make the braking system morecheaper.

Performance of hybrid nano-micro reinforced mg metal matrix composites brake calliper: simulation approach

Most commercial vehicles use brake calliper made of grey cast iron (GCI) which possesses heavy weight. This contributes to the total weight of the vehicle which can lead to higher fuel consumption. Another major problem is GCI calliper tends to deflect during clamping action, known as “bending of bridge”. This will result in extended pedal travel. Magnesium metal matrix composites (Mg-MMC) has a potential application in the automotive industry since it having a lower density, higher strength and very good modulus of elasticity as compared to GCI. This paper proposed initial development of hybrid Mg-MMC brake calliper. This was achieved by analyzing the performance of hybrid nano-micro reinforced Mg-MMC and comparing with the conventional GCI brake calliper. It was performed using simulation in ANSYS, a finite element analysis (FEA) software. The results show that hybrid Mg-MMC has better performance in terms of reduction the weight of the brake calliper, reduction in total deformation/deflection and better ability to withstand equivalent elastic strain.

Study on Braking Sensation Based on Urban Working Conditions

In this paper we researched the vehicle braking sense in three aspects of human, vehicle and environment and analysed their impacts on brake feeling. Through the real vehicle test we analysed the relationship among pedal force, pedal travel and deceleration. We used dynamometer test method to study the brake noise question. We designed a fixture which could imitate the suspension and made the test more close to the true level. Moreover we discussed how to establish the evaluation system of vehicle braking condition. Through real vehicle test of braking, we can test and record the brake system parameters in the braking process under urban working conditions. We recorded the brake frequency, the change of brake speed and brake disc temperature. Meanwhile, based on the analysis of braking condition, we put forward the index of brake load to reflect the city’s traffic conditions. Experiment show that the braking condition and brake feel are related, braking condition also provides theoretical support for the design of brake system.

Research on the Intelligent Control and Simulation of Automobile Cruise System Based on Fuzzy System

In order to improve the active safety driving vehicle and alleviate the intension of driving fatigue, an intelligent control strategy of automobile cruise is put forward based on the throttle or braking pedal combined control adopting the fuzzy control theory. A fuzzy logic controller is presented, which consists of the two input variables, the deviation of the theoretical safe distance and relative distance and the relative velocity between the preceding vehicle and the cruise vehicle, and the single output variable, that is, the throttle opening or the braking pedal travel. Taking the test data of 1.6 L vehicle with auto-transmission as an example, the function on the intelligent cruise control system is simulated adopting MATLAB/Simulink aiming at different working conditions on the city road. The simulation results show that the control strategy possesses integrated capability of automated Stop &amp; Go control, actively following the preceding vehicle on the conditions of keeping the safety distance and the constant velocity cruise. The research results can offer the theory and technology reference for setting dSPACE type and developing the integrated control product of automobile cruise system.

A dynamic model for brake pedal feel analysis in passenger cars

The brake system of a passenger car is a complex system composed of an assembly of mechanical parts, such as springs and rubber parts, and structures filled with gas and other liquids. In order to predict the brake pedal feel of a passenger car, a dynamic model of a brake system during application of the brake pedal was proposed; this considered and modelled the physical structures and the working processes of the key components. The model takes into account not only the spring preloads and the frictional forces in the booster and the master cylinder but also the reaction disc features and the variation in the bulk modulus of the brake fluid. When the pedal travel is regarded as the input, the boundary conditions for the dynamic equations of the brake system components are strictly defined. Also, bench experiments for the booster and the master cylinders were designed for parameter identification; the effectiveness of the component models was validated under conditions including with and without vacuum assist and with and without brake fluid. On the basis of these experiments, the static and dynamic characteristics of the brake pedal feel were simulated using the static model and the dynamic model of the brake system. Then, vehicle road experiments were carried out. With the assessment index of a three-quadrant diagram covering the pedal travel, the pedal force and the master cylinder pressure, as well as a four-quadrant diagram covering the pedal travel, the pedal force, the master cylinder pressure and the longitudinal deceleration of the vehicle, the results from the simulations and the experiment were compared and analysed. We conclude that this novel model of a brake system can accurately predict the brake pedal feel characteristics of passenger cars and can be used for brake system design and adjustment.

Brake Pedal Feel Verification of the Energy Recovery System

Brake pedal feel is intuitive feelings for the driver and affected vehicle safety performance. Due to the participation of the motor, brake force distribution and the original pedal feel of the driver would be changed. Based on the traditional hydraulic unit of ESC, Jilin University developed a braking energy recovery system of uniaxial decoupled. A series of fixed partition coefficient control strategy was developed, coordinated control of electrical regenerative braking and hydraulic braking was carried out. Vehicle test was carried out for coordinated braking strategy, parallel strategy and traditional control strategy. Vehicle test results show that the brake pedal travel simulator and the coordinated braking strategy can improve the energy recovery, and ensure that the brake pedal feel is consistent with the traditional vehicle.

Design and Simulation of Pedal Simulator in Brake by Wire System

Wire of the brake pedal is not directly connected to the hydraulic environment in the braking By-wire system so the driver has no direct pedal feel. Then pedal simulator is an important part in the brake-by-wire system. A pedal force simulator was designed based on the traditional brake pedal curve of pedal force and pedal travel, AMESim and Matlab / Simulink were used as a platform to build simulation models and control algorithms. The simulation results show that the pedal stroke simulator and the control strategy meet the performance requirements of traditional braking system. It can be used in brake by wire system.

Study on Regenerative Braking Control Algorithm

Based on the traditional hydraulic unit of ESC, Jilin University developed a braking energy recovery system of uniaxial decoupled. A first-order hysteresis filtering method with filtering time factor adaptively corrected was used to calculate driver's braking demand based on pressure of the master cylinder. A series of fixed partition coefficient control strategy was developed, coordinated control of electrical regenerative braking and hydraulic braking was carried out. Vehicle test was carried out. Vehicle test results show that the brake pedal travel simulator and the braking control strategies can improve the energy recovery, and ensure that the brake pedal feel is consistent with the traditional vehicle.

Neuro-genetic optimisation of disc brake speed sensitivity

Since the driver obtains important feedback of a vehicle's dynamics and its braking capabilities depending on the change of brake performance, it represents an important aspect of a vehicle's performance and its quality of use. Sensitivity of braking torque vs. the friction couple interaction, under different braking conditions, is one of the most important properties of the disc brake. In this paper, we investigated possibilities for an intelligent dynamic optimisation of automotive braking system performance. The hybrid neuro–genetic optimisation model was developed in order to perform dynamic control and optimisation of the disc brake performance during a braking cycle. This model provided stabilisation of the brake performance and their maximisation vs. the brake pedal travel, selected by the driver, and the influence of the initial speed during a braking cycle. The model provided the disc brake actuation pressure which is adjusted upto the level that provides stable and, for current braking regimes, maximum braking torque values.

Design optimization of an opposed piston brake caliper

Successful brake caliper designs must be light and stiff, preventing excessive deformation and extended brake pedal travel. These conflicting requirements are difficult to optimize owing to complex caliper geometry, loading and interaction of individual brake components (pads, disc and caliper). The article studies a fixed, four-pot (piston) caliper, and describes in detail the computer-based topology optimization methodology applied to obtain two optimized designs. At first sight, relatively different designs (named ‘Z’ and ‘W’) were obtained by minor changes to the designable volume and boundary conditions. However, on closer inspection, the same main bridge design features could be recognized. Both designs offered considerable reduction of caliper mass, by 19% and 28%, respectively. Further finite element analyses conducted on one of the optimized designs (Z caliper) showed which individual bridge features and their combinations are the most important in maintaining caliper stiffness.