Brake by wire control with pedal feedback and brake boost

"By wire" technology merged into multiple vehicular subsystems, including gear changing, drive, and braking systems. The brake by wire system is developed to overcome the problems associated with the integration of mechanical and hydraulic systems in novel vehicular systems. Even though brake by wire systems has potential advantages, the conventional brake systems' tactile sensation will be removed if migrated to the electrical by wire control scheme. This paper proposes a novel control mechanism that provides amplification of force, scaling of position replication, and a virtual spring-damper based pedal retraction which provides bilateral brake force feedback to the driver's pedal similar to the hydraulic brake system. The proposed system performance was simulated and tested using a bilateral teleoperation system with disturbance observers (DOB) and reaction force observers (RFOB). The proposed system provides pedal force amplification and brake force feedback to the driver's pedal using RFOBs. The virtual spring retracts the brake pedal, similar to a mechanical pedal retraction system. The system simulation and experimental results provide evidence of the proposed system's force amplification, position scaling, and pedal reaction capabilities.

Conceptual design evaluation of concurrent brake actuator mechanism

The proper amount of braking force on both wheels is needed to optimize the braking performance and stability of the motorcycle. The braking effectiveness can be maximized by keeping the ideal nonlinear brake force distribution during braking. Thus the purpose of this research is to present a mechanism that can be accommodated as a Concurrent Brake Actuator (CBA) design to control the ideal nonlinear brake force distribution. In this paper, the conceptual design of the CBA mechanism is developed to be used as a based design for CBA development. Thus, two conceptual designs of the CBA mechanism have been generated. The proposed concept designs were evaluated based on Design Failure Mode and Effect Analysis (DFMEA) and SOLIDWORKS Motion Analysis. The potential failure of the CBA concept design was determined based on the risk priority number (RPN) in DFMEA. The information obtained from DFMEA was used in SOLIDWORKS Motion Analysis to identify stress performance analysis for each CBA conceptual design. Then, the best CBA concept design will be selected. The selection was made based on the highest score gained by the CBA concept design in qualitative evaluation. Based on the results, the fixed main body design with a tilted position linear slope in CBA Design I is potentially to actuate and distribute the nonlinear brake force to the front and rear brake with less potential of failure. Therefore, the proposed mechanism design will be used as a based mechanism design for CBA development.

ON THE QUESTION OF BRAKING ARTICULATED BUSES

The safe movement of a car and a road train is largely determined by its braking properties. The nature of the movement of the road train is fundamentally different from the movement of a single car. The difference can be explained by the presence of additional forces arising in the articulation of the links of the vehicle, as well as forces and moments acting on its individual links and the movement of the vehicle as a whole. Their effect is especially noticeable when braking a road train, which may be accompanied by folding links and loss of stability of the vehicle. As a result of the study, the optimal values of the brake force distribution coefficients for a fully loaded articulated bus are obtained, which provide both high braking efficiency and the stability of the articulated bus (AВ) during braking. The coefficients are determined taking into account the design features of the brake mechanisms and their geometric dimensions, providing the required braking performance. For the selected values of the braking force distribution coefficients along the axes of the AВ and the coefficients that take into account the design features of the braking mechanisms and their geometric dimensions, the braking distance during braking by the main or working braking system and the spare one satisfy the requirements of regulatory documents. With the selected asynchronous response of the brake drives of the bus and trailer, the steady deceleration of the АВ is slightly less than the standard.

Comparative assessment of braking properties of operated passenger cars, according to brake wear

The article proposes a method for assessing the change in the braking properties of passenger cars during operation following a change in the main characteristic of the brake system - the coefficient of distribution of braking forces between the axles of vehicles, both equipped and not equipped with tracking systems for the braking process by installing brake force regulators in the brake circuits, working according to different laws of changing the drive pressure. The aim of the work is a comparative assessment of the braking efficiency of passenger cars using the example of Lanos cars, the braking systems of which are equipped with various devices for changing the coefficient of distribution of braking forces between the axles, under changing operating conditions. It is known that braking efficiency is an indicator characterizing the braking properties and the ability of a car to maintain a given law of motion during braking, which is determined both by the nature of the adhesion properties of the wheels to the road and the capabilities of the braking system itself to implement these properties. Since the operating conditions of passenger cars significantly affect the braking properties, in order to ensure the required braking efficiency, it is necessary to take into account the change in the primary distribution coefficient of the braking forces generated by the braking mechanisms and the change in their implementation during the operation period. In order to assess the change in the braking properties in the general case of the operation of a passenger car, the dependence of the actual coefficient of distribution of braking forces between the axles on the braking coefficient was proposed. Moreover, the value of the coefficient of distribution of braking forces between the axles depends both on the type of laws of regulation of braking forces and on the residual values of the parameters of braking systems that determine these laws. These dependences on the parameters of the braking systems and the parameters of the passenger car in operation are a function of the goal for determining the residual output characteristics of its braking system.

Calculation of brake-force distribution on three-axle agricultural trailers using simulation methods

The paper presents a new methodology for calculating the optimal linear distribution of braking forces for a three-axle trailer with "walking beam" and "bogie" suspension of the rear axle assembly that will meet the requirements of the new European legislation, EU Directive 2015/68. On this basis, a computer program for selecting the linear distribution of braking forces between axles has been developed. The presented calculations and simulation results of the braking process can be used in the design process to select the parameters of the wheel braking mechanisms and then the characteristics of the pneumatic valves of the braking system. The adaptation of the braking system of agriculture trailers is a very important factor for improving the safety of the transportation systems.

Prediction Model and Experimental Study on Braking Distance under Emergency Braking with Heavy Load of Escalator

In order to study the relationship between the braking distance and the load of escalator and realize the prediction of the rated load braking distance with a little load, the method of combining theoretical analysis and experimental research is used. First, the dynamic characteristics of the escalator during emergency braking are analyzed, and the prediction model of the braking distance of the escalator under different loads is derived based on the law of conservation of energy. Furthermore, the influence coefficients under different loads were determined through experimental studies, the model was revised, and the concept of equivalent no-load kinetic energy (ENKE) was proposed. The research shows that the braking distance of the escalator increases nonlinearly with the increase in load. When the no-load braking distance and the 25% rated load braking distance change greatly, the braking distance increases faster as the load increases; the escalators with large brake force have a small ENKE and are easy to stop. Otherwise, it is difficult to stop. The test results show that the comparison between the predicted value of the prediction model and the measured value has a maximum error of 2.7%, and the maximum error at rated load is only 2.0%, which fully meets the needs of engineering measurement. And the prediction method reduces test costs, enhances test security, and improves test coverage.

A finite element analysis (FEA) approach to simulate the coefficient of friction of a brake system starting from material friction characterization

The coefficient of friction (COF) is one of the most important parameters to evaluate the performance of a brake system. To design proper brake systems, it is important to know the COF when estimating the brake force and resulting torque. It is challenging to simulate the COF since friction in disc brakes is a complex phenomenon that depends on several parameters such as sliding velocity, contact pressure, materials, and temperatures, etc. There is a lack of studies found in the literature focusing on simulation of the COF for a full brake system based on tribometer material characterization. The aim of this work is therefore to investigate the possibility to use a finite element analysis (FEA) approach combined with a COF pv-map to compute the global COF of a disc brake system. The local COF is determined from a pv-map for each local sliding velocity and contact pressure determined by the FEA. Knowing the local COF, the braking force of the entire brake system and the global COF can be evaluated. Results obtained by the simulation are compared with dyno bench test of the same brake system to investigate the validity of the simulation approach. Results show that the simulation is perfectly in line with the experimental measurements in terms of in-stop COF development, but slightly higher with a positive offset for every braking.

Numerical Study on the Delay Effect of Air Brake Mass Flow on Train Coupler Forces

In existing freight-train braking systems, braking is applied on individual cars sequentially at the speed of the air pressure. In the case of long trains that consist of hundreds of rail cars, there is a time delay that results in large and impulsive compressive and tensile coupler forces. These coupler forces compromise the train safe operation and stability, make train handling difficult, cause track damage, raise significantly the maintenance cost, and increase the stopping distances which can lead to serious accidents. The objective of this investigation is to investigate the effect of the brake-delay time on the train longitudinal dynamics (LTD) coupler forces by integrating for the first time detailed three-dimensional coupler and air-brake force models. A spatial non-linear coupler model that takes into account the geometric nonlinearities is employed in order to allow for capturing arbitrary three-dimensional rail-car motion and coupler kinematic degrees of freedom that cannot be captured using existing simpler models. This coupler model is integrated with a detailed air brake model that consists of the locomotive automatic brake valve, air brake pipe, and car control unit (CCU) in order to evaluate conventional air brake force models that account for the air-flow effect in long train pipes as well as the effect of leakage and branch pipe flows. The coupling between the air brake, locomotive automatic brake valve, car control units, and train equations is established and used in the nonlinear LTD simulations, which are performed using the computer software ATTIF (Analysis of Train/Track Interaction Forces). Different LTD braking scenarios are considered and the effect of brake signal time delay on the coupler forces is examined. The results obtained in this study demonstrate the importance of applying all brake forces simultaneously in order to ensure train stability and safety.

Sliding Mode Control of Vehicle Equipped with Brake-by-Wire System considering Braking Comfort

For passengers, the most common feeling during running on the bumpy road is continuous vertical discomfort, and when the vehicle is braking, especially the emergency braking, the instantaneous inertia of the vehicle can also cause a strong discomfort of the passengers, so studying the comfort of the vehicle during the braking process is of great significance for improving the performance of the vehicle. This paper presented a complete control scheme for vehicles equipped with the brake-by-wire (BBW) system aiming at ensuring braking comfort. A novel braking intention classification method was proposed based on vehicle braking comfort, which divided braking intention into mild brake, medium comfort brake, and emergency brake. Correspondingly, in order to improve the control accuracy of the vehicle brake system and to best meet the driver’s brake needs, a braking intention recognizer relying on fuzzy logic was established, which used the road condition and the brake pedal voltage and its change rate as input, output real-time driver's braking intention, and braking intensity. An optimal brake force distribution strategy for the vehicle equipped with the BBW system based on slip rate was proposed to determine the relationship between braking intensity and target slip ratio. Combined with the vehicle dynamics model, improved sliding mode controller, and brake force observer, the joint simulation was conducted in Simulink and CarSim. The cosimulation results show that the proposed braking intention classification method, braking intention recognizer, brake force distribution strategy, and sliding mode control can well ensure the braking comfort of the vehicle equipped with the BBW system under the premise of ensuring brake safety.