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Technical Paper

Automotive Autonomous Braking Systems by using Artificial Intelligence and Sensor Technology

2024-09-08
2024-01-3055
Advanced Driver Assistance System [ADAS] is current trending technology in Automotive industry which provide the driverless features to Autonomous business. Along with ADAS technology Artificial Intelligence [AI] and Machine learning [ML] techniques have major superior impact to the driverless vehicles. In any vehicle, brake & communication system plays vital role along with sensor technology. AI-driven autonomous vehicles can revolutionize the automobile enterprise by lowering the injuries, increasing mobility which reduces the impact to passengers and surrounding environment. Sensor technology calculates the degree of danger, relative distance & speed between vehicles as inputs and provide the information to the vehicles central unit to take necessary actions accordingly. Braking systems such as Emergency Brake System (EBS), EBS Cross and Pedestrians functions supports the driver in critical situations, warns with a visual/audible alert and intervenes with full braking if necessary.
Technical Paper

Brake Particle Emission Influenced by Grooved Disc Friction Surfaces With Or Without A Hard Coating

2024-09-08
2024-01-3030
Many performance sport passenger vehicles use drilled or grooved cast iron brake rotors for a better braking performance or a cosmetic reason. Such brake rotors would unfortunately cause more brake dust emission, appearing with dirty wheel rims. To better understand effects of such brake rotors on particle emission, a pin-on-disc tribometer with two particle emission measurement devices was used to monitor and collect the emitted airborne particles. The first device was a fast mobility particle sizer, measuring particles ranging from 5.6 to 560 nm in 32 size channels. The second device was an electrical low pressure impactor to measure and collect particles from 6 nm to 10 μm at 14 size-resolved stages. The testing samples were scaled-down brake discs (100 mm in diameter) against low-metallic brake pads. Two machined surface conditions (plain and grooved) with uncoated or ceramic-coated friction surfaces were selected for the investigation.
Technical Paper

Niobium Alloyed Ferritic Nitrocarburized Brake Rotors

2024-09-08
2024-01-3031
Brake rotor wear durability and resistance to dust generation are under increasing demands to meet proposed environmental requirements. Improved rotor output, or the ability to turn kinetic energy into heat are driving more aggressive friction materials that increase wear of the brake rotor. Regenerative braking systems have unique challenges in corrosion cleanability that require aggressive friction materials in combination with good corrosion performance. Grey cast iron remains the material of choice for brake rotors due to the advantages of near net shape capability, good thermal conductivity, and low cost. Niobium (Nb) alloyed Grey cast iron in combination with Ferritic Nitrocarburize (FNC) case hardening heat treatment is proposed to improve wear resistance and reduce brake dust generation of brake rotors. Niobium additions in cast iron were shown in prior investigations to reduce the eutectic cell size and refine the pearlite matrix.
Technical Paper

A Study on the countermeasure to EURO7 Brake Dust Regulation Phase 1

2024-09-08
2024-01-3049
In order to cope with the brake dust regulation of EURO7, countermeasures were listed, and evaluation and verification studies were conducted on them. Through this phase1 study, it was most reasonable to apply hard metal cladding disks to front brake and apply friction materials as NAO with less dust generation to rear brake. This is because it is possible to Satisfy new regulations without deteriorating the required performance in Europe. However, it is necessary to develop detailed specifications of discs and friction materials to satisfy our braking development goals in the Phase 2 to optimize performance target for European models.
Technical Paper

Effective way to eliminate and reduce Brake Judder issue during combined cornering & braking event in the SUV

2024-09-08
2024-01-3048
Brake judder is a forced vibration problem occurring during combined cornering& braking events. The vibration frequency is directly proportional to the revolution speed of the wheel and therefore also to the velocity of the vehicle. In the higher frequency range, the structural vibrations are accompanied by a sound. Furthermore, a specific type of judder, so-called hot judder, is related to disc cracking. The driver experiences judder as vibrations in the steering wheel, brake pedal and floor. The brake judder is caused by uneven and local touching of brake pad with rotating disc. One of the primary reasons for this is the lateral deflection of the brake disc with respect to the caliper due to lateral or vertical load variations. If the brake caliper is mounted above the axle horizontal center line, then the judder increases further.
Technical Paper

Research on acceleration slip regulation for battery electric vehicle

2024-09-08
2024-01-3051
As an important part of the automotive electronic control system, the acceleration slip regulation takes the tire slip rate as the main control target. By controlling the wheel driving force, the tire maintains a stable adhesion state to obtain good handling stability and power.This paper takes electric vehicles with independent front and rear axles as the research object, and studies the application of acceleration slip regulation in vehicle drive control.At present, the main technologies for acceleration slip regulation of electric vehicles include: logic threshold control, PID control, sliding mode control and fuzzy control. Since the car is a complex and changeable system, using one of the above methods alone to control car slippage may not yield ideal results.
Technical Paper

Comprehensive Study on Challenges to introduce AEBS feature in Indian Perspective

2024-09-08
2024-01-3050
India is a diverse country in terms of road conditions, road maintenance, traffic conditions, traffic density, quality of traffic which implies presence of agricultural tractors, bullock carts, autos, motor bikes, oncoming traffic in same lane, vulnerable road users (VRU) walking in the same lanes as vehicles, VRU’s crossing roads without using zebra crossings etc. as additional traffic quality deterrents in comparison to developed countries. The braking capacity of such vivid road users may not be at par with global standards due to their categories, maintenance, loading beyond specifications, driver behavior which includes the tendency to maintain a close gap between the preceding vehicle etc. which may lead to incidents specifically of rear collisions due to the vehicle going through an emergency braking event.
Technical Paper

Application of Machine Learning Models to Enable Virtual Development Of High Performance Brake Systems

2024-09-08
2024-01-3053
The once rarified field of Artificial Intelligence, and its subset field of Machine Learning have very much permeated most major areas of engineering as well as everyday life. It is already likely that few if any days go by for the average person without some form of interaction with Artificial Intelligence. Inexpensive, powerful computers, vast collections of data, and powerful, versatile software tools have transitioned AI and ML models from the exotic to the mainstream for solving a wide variety of engineering problems. In the field of braking, one particularly challenging problem is how to represent tribological behavior of the brake, such as friction and wear, and a closely related behavior, fluid consumption (or piston travel in the case of mechatronic brakes), in a model.
Technical Paper

Moisture Adsorption and Compression Deformation Behavior of Semimet vs. NAO Brake Pads: Effect of Pad Cure Temperatures and Moisture Adsorption on Low-Speed Friction

2024-09-08
2024-01-3056
Moisture adsorption and compression deformation behaviors of Semimet and Non-Asbestos Organic brake pads were studied and compared for the pads cured at 120, 180 and 240 0C. The 2 types of pads were very similar in moisture adsorption behavior despite significant differences in composition. After being subjected to humidity and repeated compression to 160 bars, they all deform via the poroviscoelastoplastic mechanism, become harder to compress, and do not fully recover the original thickness after the pressure is released for 24 hours. In the case of the Semimet pads, the highest deformation occurs with the 240 0C-cure pads. In the case of the NAO pads, the highest deformation occurs with the 120 0C-cure pads. In addition, the effect of pad cure temperatures and moisture adsorption on low-speed friction was investigated: in both cases, the highest friction is associated with the pad cure temperature of 240 0C.
Technical Paper

Modeling and Simulation of Electronic Brake Booster with Fuzzy Logic Control

2024-09-08
2024-01-3052
On one hand, simulation tools are widely used to study and examine new technologies before building prototypes. It is a cost- and time-saver if it is well mathematically modelled and in real-time simulated. On the other hand, the expansion of electric and hybrid vehicle development requested advancing the Electronic Brake Booster (EBB) technologies. In this paper, a simulation tool for the EBB is developed to simulate the performance in real time with a very quick response compared to the previous models with a novel fuzzy logic control (FLC) for the position tracking control. The configuration of the EBB is established, and the system model, including the permanent magnet synchronous motor (PMSM), a double reduction transmission (gears and a ball screw), a servo body, a reaction disc, and the hydraulic load, is modeled. The load-dependent friction has been compensated by using the Karnopp-friction model. FLC has been used for the control algorithm.
Technical Paper

Brake Heat Capacity Prediction by Machine Learned Friction Coefficient Model and Virtual Wheel Brake Co-Simulation

2024-09-08
2024-01-3054
In recent times, the increasing complexity of systems and diverse customer demands have necessitated highly efficient vehicle development processes. Accurate prediction of vehicle performance through simulation enables the determination of design specifications before building test vehicles, leading to reduced development schedules and costs. Especially with the transition to electrification in the automotive industry and the diversification of mobility businesses, the rear axle load for xEV has increased compared to conventional ICE vehicles. Detailed brake thermal performance predictions are now required not only for the front brake but also for the rear brake. Moreover, scenarios requiring verification, such as alpine, which applies braking severity to xEV with the regenerative braking system, have become more diverse.
Technical Paper

Low-Speed Stop and Near Zero-Speed Start-to-Move Brake Noise: Effect of Moisture Adsorption, Prior Braking and Deceleration Rate

2024-09-08
2024-01-3057
The influence of moisture adsorption, prior braking conditions and deceleration rates on the low-speed braking noise has been investigated, using copper-free disc pads on a passenger car. With increasing moisture adsorption time, decreasing severity of prior braking or increasing deceleration rate, the noise sound level increases for the air-borne exterior noise as well as for the structure-borne interior noise. The near-end stop noise and the near zero-speed start-to-move noise show a good correlation. Also, a good correlation is found between the noise measured on a noise dynamometer and on a vehicle for the air-borne noise. All the variables need to be precisely controlled to achieve repeatable and reliable results for dynamometer and vehicle braking noise tests.
Technical Paper

Piston and Guide-Pin Rattle Noise Mitigation in Electro-Mechanical Brake Caliper

2024-09-08
2024-01-3032
The hydraulic brake caliper utilizes pressurized brake fluid to actuate one or multiple pistons generating friction between the brake pads and disc. Calipers are classified into floating and fixed type caliper. Floating caliper slides inboard/outboard direction to apply and release pressure on the outer pad. This type of caliper has rubber or spring components to maintain specific clearance for sliding characteristics. Therefore, caliper rattle noise could occur due to wheel vibrations when the vehicle is driven on unpaved roads or rough surfaces. Rattle noise is particularly pronounced in front calipers positioned closer to the driver and its susceptibility tends to increase with the weight of the caliper. The Electro-Mechanical Brake (EMB) caliper has gained substantial attention in automotive industry for its advantages features including reduced brake drag, optimized vehicle layout and precise brake control.
Technical Paper

Analysis of Stick-Slip Phenomenon During Creep Groan Using Acoustic Emission Sensing

2024-09-08
2024-01-3033
When the brakes are released and the vehicle starts on a slope, the brakes and suspensions vibrate and the car body resonates, generating a noise between 10 to 300 Hz, which is called brake creep groan. This low-frequency noise is more likely to occur in high-humidity environments. As vehicles become quieter with the introduction of EVs, improving this low-frequency noise has become an important issue. It is known that the excitation force is the stick-slip between the brake rotor and pads, but there are few studies that directly analyze stick-slip occurring in a vehicle. Acoustic emission (AE) is a phenomenon in which strain energy stored inside a material is released as elastic stress waves, and AE sensing can be used to elucidate the friction phenomena. In this study, the AE sensing is used to analyze changes in the stick-slip occurrence interval and generated energy when creep groan occurs. As a result, it was confirmed that the AE signal increased with high humidity.
Technical Paper

Comprehensive Methodology for Quantitative Prediction and Experimental Validation of Brake Rattle Noise Across Diverse Mounting Orientations of Disc Brake System

2024-09-08
2024-01-3034
In the automotive industry, Noise-Vibration-Harshness (NVH) performance has undergone significant evolution, transitioning from merely meeting performance requirements to prioritizing user comfort. Specifically, within the realm of vehicle NVH, various areas such as drivetrain, wind noise, engine noise, and brake noise have garnered attention. While older vehicles primarily emphasized performance needs, modern automotive design increasingly revolves around ensuring user comfort and satisfaction. One notable aspect of NVH improvement lies in brake systems, where manufacturers are now engineering products to meet stringent Original Equipment Manufacturer (OEM) criteria. This focus on enhancing brake NVH aims to enhance user comfort and ultimately boost customer satisfaction. The rise of electric vehicles, characterized by their minimal engine noise (around 40 – 50 dB), has accentuated the significance of reducing noise generated by brake systems, particularly rattle noise.
Technical Paper

Objectively quantify creep groan and dynamic grunt performance of different brake friction materials

2024-09-08
2024-01-3035
The assessment of brake friction materials extends beyond squeal noise and thermal roughness testing as it play crucial role in other brake noise phenomena such as creep groan and dynamic grunt. These low frequency noise types are significant as they directly affect passengers comfort levels. Creep groan noise defined as audible stick-slip noise at low vehicle speed during partial brake application, typically encountered in dense traffic conditions. Dynamic grunt is another form of stick-slip noise observed during high-speed braking and it is noticeable just prior to vehicle’s complete stop. This noise is indicative of frictional interaction between the brake pad and disc under deceleration scenario. Comparative analysis of two distinct brake friction materials was conducted utilizing both NVH dynamometer and real-world vehicle testing. The NVH dynamometer procedure was designed to evaluate the creep groan and dynamic grunt phenomena under controlled environmental conditions.
Technical Paper

Investigation on Brake-Drag-Optimization on Vehicle-Level

2024-09-08
2024-01-3037
Brake drag in disc brakes occurs during the off-brake-phase, when the brake is not applied but friction contacts between brake disc and pads persist. First and foremost, the resulting drag torque increases energy consumption, where a few Newton meters can have a significant impact on the range which is a crucial feature in particular for battery-electric-vehicles. Moreover, brake wear is accelerated in conjunction with enlarged taper-wear of the pads. Additional wear can also imply increased brake particle emissions which are going to be limited by upcoming regulations due to their potential health risk. In this light different countermeasures aim to create and maintain a sufficient air gap between brake disc and pads after the brake is released. Common examples are the optimization of the piston sealings and the corresponding seal-grooves to improve piston retraction as well as integrating pad springs into the caliper to push the pads back.
Technical Paper

Analysis of Disc-Brake Squeal Considering Lining Wear

2024-09-08
2024-01-3036
Brake squeal is known as phenomenon caused by various factors such as stiffness of brake components, mode coupling, friction coefficient, friction force variation, pressure, temperature and humidity. FEA simulation is effective in predicting and investigating the cause of brake squeal, and is widely used. However, in many FEA simulations, models of brake lining are mostly a brand-new shape, so that the change of pressure distribution or pad shape, which can occur due to the lining wear, are not taken account. In this research, brake squeal analysis was conducted with consideration of lining wear, applying Fortran codes for Abaqus user subroutine. The brake assembly model for the analysis, created by using a 3D scanner, has a close shape to the real one. The wear patterns calculated by the analysis are similar to those of brake pads after a noise test. The complex eigenvalue analysis shows two unstable modes at the frequency of squeal occurred in the noise test.
Technical Paper

Glow-discharge Optical Emission Spectroscopy Study of Cr(III) Sealing in Anodized Aluminium-Silicon Alloys for Brake Component

2024-09-08
2024-01-3038
Calipers and pistons for high-end car braking systems are typically realized using anodized Aluminium-Silicon alloys. Indeed, Aluminium-Silicon alloys are light materials with optimal mechanical properties and, when anodized, excellent corrosion and wear resistances. To achieve these top-notch surface properties, the anodizing process is followed by a sealing post-treatment, which significantly improves the corrosion resistance and tunes the tribological properties (e.g., hardness and friction coefficient) of the anodized pieces. Sealing consists in the precipitation of insoluble hydroxides and functional compounds (e.g., corrosion inhibitors) inside the nano-pores of the anodic layer. Nevertheless, sealing might not penetrate through all the nano-porous structure of the anodic layer. Thus, in light of possible post-machining of sealed, anodized components, it appears fundamental to develop a tool to determine the depth penetration of sealing inside the anodic layer.
Technical Paper

Application of Topology Optimization and Artificial Intelligence Based Evolutionary Algorithm to Minimize the Contribution of the Caliper in Brake Squeal Noise

2024-09-08
2024-01-3039
The squeal noise is one of the critical factors to qualify a disc brake design. It is imperative to be watchful of the unstable natural modes of the brake assembly which triggers squeal. Any design modification for reducing a part's contribution to targeted squeal mode can adversely affect and give rise to new squeal modes. Also, controlling conflicting requirements like mass, strength, and casting manufacturability, further adds up complexity, which increases design iterations and product cost. In view of these challenges, the application of the topological optimizations embedded under an artificial intelligence (AI) driven workflow is explored for a brake assembly. The scope of optimization is kept limited to only the caliper. A complex or unsymmetrical eigenvalue (EV) finite element analysis (FEA) of brake assembly is performed on the baseline design which predicts a squeal mode having 35% strain energy contribution from caliper.
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