Brake Pedal Research Articles

Proposal of Simulation Algorithm of Driver's Brake Pedal Force

Proposal of Simulation Algorithm of Driver's Brake Pedal Force

Posture and muscular behaviour in emergency braking: An experimental approach

In the field of numerical crash simulations in road safety research, there is a need to accurately define the initial conditions of a frontal impact for the car occupant. In particular, human models used to simulate such impacts barely take into account muscular contracting effects. This study aims to quantify drivers’ behaviour in terms of posture and muscular activity just before a frontal impact. Experiments on volunteers were performed in order to define these conditions, both on a driving simulator and on a real moving car. Brake pedal loads, lower limbs kinematics and muscle activation were recorded. Coupling instantaneous data from both experimental protocols (simulator versus Real car), a standard emergency braking configuration could be defined as (1) joint flexion angles of 96°, 56° and 13° for the right hip, knee and ankle respectively; (2) a maximum brake pedal load of 780 N; (3) a muscular activation of 55% for the anterior thigh, 26% for the posterior thigh, 18% for the anterior leg and 43% for the posterior leg. The first application of this research is the implementation of muscle tone in human models designed to evaluate new safety systems.

Fuzzy Longitudinal Controller Design and Experimentation for Adaptive Cruise Control and Stop&Go

This paper presents a fuzzy longitudinal control system with car-following speed ranging from 0 to 120 km/h, thereby achieving the main functions of both adaptive cruise control (ACC) and Stop&Go control. A fuzzy longitudinal controller is synthesized by inputting the difference of the actual relative distance and the safe distance obtained from the preceding vehicle, and the relative speed, and then outputting the pulse-width-modulation (PWM) signal to control the output forces of the vacuum boosters. With the use of the high-level controller from dSPACE, the fuzzy control law is easily and rapidly implemented using Matlab/Simulink for the experimental car, and the controller’s parameters can be changed and updated by analyzing data based on the relative distance using Lidar, the speed of the host vehicle, the opening of the throttle and the position of the braking pedal. For the sake of safe driving, experimental results are conducted by simulating the various possible car-following conditions for the ACC and Stop&Go controllers, thereby obtaining virtually relative distances and speeds to tune the controller’s parameters and ensure the safety of the controller. Several car following experiments are conducted to show that the proposed fuzzy longitudinal controller is capable of achieving the requirements of comfort and safety, and giving a satisfactory performance at high and low speed conditions.

Simultaneous interaction with in-vehicle systems while turning left: comparison among three groups of drivers

The growing introduction of new technologies inside vehicles represents a set of extra information sources. Its use can interfere with the driving activity and induce performance decrements. An on-road experiment was conducted to investigate how drivers reacted to the simultaneous interaction with in-vehicle systems. Forty-eight subjects (elderly, reference and novice) participated in the tests. They were asked to interact with one (road guidance system) or two (road guidance system and mobile phone) on-board devices. Their performance was evaluated for the turn left manoeuvres and main effects of system conditions were revealed. The simultaneous interaction with both in-vehicle systems induced participants to some performance decrements on the driving task: higher number of late activations of the turning indicator; lower mean speeds before the intersection; lower values of instant speed at the beginning of the turn manoeuvre; higher steering wheel variability; activations of the braking pedal with less pressure, later, and performing a higher number of strokes; and also less glances towards important areas of the environment. No significant difference was observed for the guidance task. The comparison between driver groups' performance did not reveal enough significant differences in order to draw a general conclusion.

Ergonomic Design in Hospital Beds: Comparison of Brake Pedal Design and Steering-assistance Features

Transporting patients using a hospital bed is a common and often difficult task in a healthcare environment. The aim of this study was to compare the usability and physical demands of alternative bed design features associated with brake engagement and bed maneuvering tasks. Specifically, the brake system and steering-assistance features of two hospital beds were evaluated within a simulated healthcare work environment. Two sets of participants were recruited from the local student population and community. Task completion time, perceived usability of brake and steering-assistance features, hand forces, and trunk kinematics were measured during the braking and maneuvering tasks to assess the usability of the bed features and the physical demands likely placed on healthcare workers. With respect to brake design, a frontal brake (when bed side rails were down) was found to be significantly less efficient than a brake located at the side or at the foot-end of the bed. During in-room maneuvering tasks, the steering-assistance feature significantly reduced hand forces and increased perceived usability. Furthermore, patient mass significantly affected required hand forces. Regardless of the use of steering-assistance features, the physical demands observed in the present study might exceed recommended ergonomic guidelines. Therefore, to improve the ergonomic design of hospital beds in terms of healthcare workers' physical effort and work efficiency, it is recommended that further ergonomic assessments should be made regarding the usability of bed design features and future improvements.

Electric Braking Control Methods for Electric Vehicles With Independently Driven Front and Rear Wheels

For electric vehicles (EVs), the most important issue is safety when driving and braking operations are performed. EVs with a structure that can drive the front and rear wheels independently have been proposed by the authors, and they are being studied as the next ECO vehicles. The basic fail-safe function has already been verified through simulations and experiments to provide stable driving without any sudden stops even when the elements constituting the driving systems fail. Then, methods to control phenomena occurring at the time of braking, which are uncontrollable only by driver's pedal operations, i.e., wheel lock, slip, and aggravation of the riding comfort, are studied here based on a prototype EV with a function that can distribute the braking torque to the front and rear wheels according to driving conditions. As a result, electric braking control methods using the estimated vehicle speed, acceleration, and load movement are proposed that can prevent vehicles from experiencing wheel lock and slip phenomena and can improve the riding comfort regardless of a driver's braking pedal operations. Effectiveness of the proposed methods is verified through experiments using the prototype EV

A Study on Load Analysis and Durability Test Condition of Automobile Brake Pedal

Automobile pedal which is loaded by driver’s input is transmitting load to throttle cable, braking device and clutch device and controlling automobile. Measuring working condition and applying equivalent damage are needed for reliability of developing pedal. The measuring working condition is requiring more investigation with various respects because of widely ranged drivers, road condition and environmental condition. Additionally, when equivalent damage is applied, there are not suitable for test condition if equivalent damage is too high level to apply or unused region. In this study, load history is measured with 95percentile customer. Measured load history is converted to stress history about critical area of pedal by FEM. There are drawn up histogram of pedal cycles and load from stress history with rain flow cycle counting method, calculated relative damage of extended stress history with Palmgren-Miner rule. From the results, calculated total relative damage is applied to calculation method of test time and load. Calculation method for test condition is carried out with three methods which are enforcing with total stress by rain flow cycle counting, representative load and blocked load. Accelerated durability test condition of pedal using with relative damage and acceleration factors are proposed.

Driving Pedal Reaction Times After Right Transtibial Amputations

Meikle B, Devlin M, Pauley T. Driving pedal reaction times after right transtibial amputations. Objectives To determine if right transtibial amputees have the potential to safely operate the foot pedals of a vehicle with their prosthetic foot, and to determine which of 4 driving techniques is associated with the fastest reaction times. Design Repeated measures. Setting Outpatient amputee clinic. Participants Ten subjects with right-sided, transtibial amputations. Intervention Brake pedal response times were measured using 4 different driving techniques: right-sided accelerator with (1) prosthesis operating both the accelerator and brake pedals, (2) prosthesis operating the accelerator and left foot operating the brake, (3) left foot operating both the accelerator and brake, and (4) left-sided accelerator with the left foot operating both the accelerator and brake. Main Outcome Measures Reaction time, movement time, total response time, and pedal configuration preference. Results Total response times were slowest using a 2-footed driving technique ( P<.001). Total response times were comparable using a left-sided accelerator versus the prosthesis. Using the left foot to operate both the accelerator and brake in a conventional right-footed accelerator design led to the fastest reaction ( P<.001) and total response times ( P<.01), although it is unclear if this is a realistic driving technique for all amputees. Conclusions Our results suggest that right transtibial amputees should be instructed not to drive with a 2-footed technique, and that they have similar pedal response times using their prosthesis when compared with a left-sided accelerator.

Pre-Impact Lower Extremity Posture and Brake Pedal Force Predict Foot and Ankle Forces During an Automobile Collision

The purpose of this study was to determine how a driver's foot and ankle forces during a frontal vehicle collision depend on initial lower extremity posture and brake pedal force. A 2D musculoskeletal model with seven segments and six right-side muscle groups was used. A simulation of a three-second braking task found 3647 sets of muscle activation levels that resulted in stable braking postures with realistic pedal force. These activation patterns were then used in impact simulations where vehicle deceleration was applied and driver movements and foot and ankle forces were simulated. Peak rearfoot ground reaction force (F(RF)), peak Achilles tendon force (FAT), peak calcaneal force (F(CF)) and peak ankle joint force (F(AJ)) were calculated. Peak forces during the impact simulation were 476 +/- 687 N (F(RF)), 2934 +/- 944 N (F(CF)) and 2449 +/- 918 N (F(AJ)). Many simulations resulted in force levels that could cause fractures. Multivariate quadratic regression determined that the pre-impact brake pedal force (PF), knee angle (KA) and heel distance (HD) explained 72% of the variance in peak FRF, 62% in peak F(CF) and 73% in peak F(AJ). Foot and ankle forces during a collision depend on initial posture and pedal force. Braking postures with increased knee flexion, while keeping the seat position fixed, are associated with higher foot and ankle forces during a collision.

Fusion of Brake Pedal Sensors in By-Wire Cars: A Fuzzy Logic Approach

By-wire braking is one of the important parts in a by-wire car from safety point of view. Because of safety critical issues, brake pedal is equipped with multiple sensors and their data must be properly fused. In addition to accuracy and robustness, mathematical complexity and computational load of the fusion method are also considered in this application. In this paper, a soft voting method is presented that uses fuzzy rule-base decision making. The fusion output is a weighted average of three sensory signals where the weights are calculated from a set of fuzzy rules. While there are only some piece-wise linear calculations in the proposed method, our experimental results show that the performance of the proposed voting method is desirable in presence of short circuits to ground or supply voltage, considerable SNR and sensor drifts. Voting error (in terms of MSE) is reduced by 82% by soft voting method, compared to simple majority (hard) voting.

Forensic Engineering Analysis And Testing For Speed Reduction In Transient Braking

The Speed From Skids Equation Is Derived From The Work-Energy Theorem And Is Often Employed In Accident Reconstruction To Determine A Vehicles Speed At The Onset Of Visible Locked-Wheel Braking Application. The Conventional Use Of This Equation In The Field Of Accident Reconstruction, However, Does Not Yield A Vehicles True Speed At The Onset Of Braking. In Maximum Application Of The Brake Pedal, A Vehicle Initially Undergoes A Transient Brake Phase Prior To Arriving At The Quasi-Steady-State Locked-Wheel Brake Phase. There Is A Reduction Of Speed That Occurs During The Transient Phase Of Braking That Is Generally Not Accounted For In The Reconstruction Of Vehicular Collisions. Accounting For This Reduction In Speed, A Forensic Engineer Can Estimate A Vehicles Speed At The Onset Of Braking And Further Employ The Relative Elapsed Time In Collision Avoidance Calculations. This Study Will Explore A Method To Estimate The Speed Reduction Occurring During The Transient Braking Based On Field Testing.

Estrogen Receptor β in Prostate Cancer: Brake Pedal or Accelerator?

Estrogens, via the interaction with their receptors, play important roles in the control of cellular growth and differentiation. Specifically, estrogens regulate the growth and development of the mammary gland in embryogenesis as well as in pre- and postpubertal periods, and of ovarian follicles during the reproductive cycle. 1 Importantly, estrogens are known to play a role in the development of the male reproductive system as well. 2 The effects of estrogens on prostate epithelium are still primarily unknown although estrogens have been used in the treatment of prostate cancer because of their growth-inhibitory effects. However, either because of toxicity and/or because of poor response rates, treatment of prostate cancer with estrogen has been discontinued.

Fault-Tolerant Drive-by-Wire Systems – Concepts and Realizations –

The development of automotive systems shows an increasing integration of electronic sensors, microcomputers and actuators for single components, engine, drive-chain, suspensions and brakes. After considering electronic driver assisting systems such as ABS, TCS, ASR, ESP, BA the developments towards drive-by-wire systems with and without mechanical or hydraulic backup are considered. Drive-by-wire systems consist of an operating unit (steering wheel, braking pedal) with an electrical output, a haptic feedback to the driver, bus systems, microcomputers, power electronics, and electrical actuators. For their design safety integrity methods like reliability, fault tree, hazard analysis and risk classification are required. Different fault tolerance principles with various forms of redundancy are considered resulting in fail-operational, fail-silent and fail-safe systems. Fault-detection methods are discussed for use in low-cost components. This is followed by some principles for fault-tolerant design of sensors, actuators and communication.A brake-by-wire system with electronic pedal and electrical brakes is then considered in more detail showing the design of the components and the overall architecture. An outlook then shows the further development of drive-by-wire systems.

Development of Composite Brake Pedal for KTX-1 and Tests for Structural Certification

A brake pedal for the flight control system of the Korean primary trainer is developed using composite material. The development includes the structural design, stress analysis, manufacturing and the qualification tests. A FEM analysis is used for the structural design and stress analysis. Autoclaving process is used to fabricate the composite brake pedal. For the qualification tests, modular fixtures are developed and applied. It is shown that the composite brake pedal developed meets all the structural integrity requirements specified in the military specification for aircraft parts.

Determination Method for Dimension of Service Braking System. 3rd Report. Calculation of Pedal Characteristics.

This paper describes the calculation methods for the characteristics of the line pressure-pedal travel and the line pressure-pedal force to estimate the braking performance and pedal characteristics of a newly designed vehicle with tandem master cylinder. The above characteristics calculated using the authors' methods and pedal force-pedal travel characteristics led by eliminating line pressure from them are compared to those of empirical results, and the validity of the calculating methods is investigated.

Preliminary Study of Brake Pedal Location Accuracy

Three experiments of brake pedal location accuracy were conducted using 24 subject drivers. The first experiment tested the accuracy of recall of drivers for the brake pedal location of the vehicle with which they were very familiar. The second experiment examined the accuracy of recall for a brake pedal location with which they had recent practice. The last experiment attempted to determine if practice with one brake pedal location would interfere with the accuracy of reproduction of a newly learned pedal location. The results of the experiments indicate that subject drivers have difficulty in reproducing the location of brake pedals. This difficulty exists for familiar brake pedal locations as well as newly learned brake pedal locations. Further there is an indication that practice with one brake pedal location may influence the accuracy of reproducing the location one newly learned.

The Occurrence of Accelerator and Brake Pedal Actuation Errors during Simulated Driving

Observations were made of subjects' foot movements while they drove an automobile simulator modified to represent the pedal, floor, and seating geometries of four actual automobiles. The type and frequency of pedal actuation errors that occurred were documented and recorded. The results indicate that a wide variety of pedal errors occur and that their frequency of occurrence varies greatly according to the seriousness of the error. Configuration differences were found for the less serious categories of error but not for the serious category.

Foot Placement and Response Latency: A Test of Fitts' Law

Response latencies were compared for three-dimensional brake/accelerator placements (depth, height, and lateral separation). Brake pedal width was found to be the only factor significantly affecting movement time. A comparison between Fitts' and Welford's movement time predictions and experimental response latencies resulted in correlations of .549 (p&lt;.0001) and .543 (p&lt;.0001). Neither movement time equations were able to predict response latencies when the brake pedal was placed 2.54 cm behind the vertical plane of the accelerator. Fitts' and Welford's equations are seen to have limited use in predicting three-dimensional foot movements.

Foot Brake Pedal Force Capability of Drivers

Abstract An experiment was conducted to provide distributions of foot force for U.S. drivers in order to derive guidelines for the maximum force requirement for actuation of an automobile service brake. The results of this study are compared with three others conducted at about the same time. Since the 5th percentile female maximum brake pedal force is about 400 newtons, it is recommended that no more than this force be required to attain near maximum braking capability from a passenger car.

Further Investigations of Movement Time between Brake and Accelerator Pedals in Automobiles

This report presents the results of continued studies into the nonoptimality of the positional relationship of brake and accelerator pedals in contemporary automobiles. Ten female subjects were tested to determine how long it takes to move the foot from the accelerator to the brake pedal under four conditions involving variations in brake pedal height and seat height. Experimental results indicated: (1) a reduction in stopping distance of upwards of 10 ft. could be effected at high speeds, (2) seat height had no effect on movement time of foot from accelerator to brake pedal in the case of female drivers, and (3) movement times for female drivers when compared with previous experiments on male drivers are the same when the brake pedal is 6 in. higher than the accelerator but are 25% slower when the pedals are in the same horizontal plane.