Front seat passengers’ experience of ride comfort and NVH in modern cars

Due to the refinements in combustion-engine and electric cars, ride comfort has become a prominent attribute when it comes to developing cars in the future. A variety of factors, such as seat, seatbelt, sound and vibration, have been shown to influence perceived overall ride comfort in passenger cars. Numerous studies have investigated human responses to sound and vibration. However, few studies have investigated passengers’ experiences of sound and vibration in real passenger cars, in different real-world driving scenarios. The purpose of this licentiate thesis is to identify human experiences of sound and vibration in modern passenger cars. An approach has been developed to investigate how sound and vibration influence overall perceived ride comfort in combustion-engine cars (CVs) and electric cars (EVs). The first research question relates to the definition of ride comfort, from the passenger’s perspective, and the methodology used to specify the factors that influence overall ride comfort. The second research question deals with specifying how ride comfort is influenced by sound and vibration.The research includes literature reviews of human responses to sound and vibration and a user study using a mixed-method research approach that focused on subjective judgements and objective measurements of overall ride comfort. The literature reviews found that several laboratory studies have covered the level and frequency ranges of interest for vibration and sound found in passenger cars. Other studies have employed realistic ride postures with populations of various ages, gender and anthropometric measures to investigate the influence of vibration on ride comfort. Studies of sound in passenger car have explored approaches to identify sound sources, assess sound quality and design product sound. The overall conclusion from the literature reviews was that there is a lack of studies that consider all the different parameters influencing the overall ride comfort experience of automotive vehicle passengers. Also, further studies are specifically needed to investigate the influence of sound and vibration on passengers’ experience of overall ride comfort. The user study comprised eight typical driving scenarios (initial comfort, start/stop, acceleration and deceleration, constant speed, speed bumps, long bumps and cornering, bridge joints and rough roads) with ten participants in a CV and an EV. The overall results indicated that the two cars were similar in terms of the prominent effects of ingress, room for the body, seat adjustment and seat support on initial comfort, but varied in terms of dynamic discomfort. Induced body movements dominated dynamic discomfort in the CV, while annoying sound dominated in the EV. Sound annoyance in the CV was primarily triggered by tyre noise at lower speeds and wind noise at higher speeds. In the EV it was the high-frequency tonal sound from electrical components that produced the most annoyance. In both cars, vibration discomfort was linked most strongly to induced body movement. Sound annoyance was judged lower when passengers perceived pronounced induced body movement or when participants experienced vibrations coherent to the sound. Nevertheless, the overall influence of sound accumulated over time, making it difficult for passengers to relax. In contrast, the instantaneous judgement of vibration discomfort was not affected noticeably by the simultaneous sound.The main conclusion of this licentiate thesis is that from the passenger’s perspective, ride comfort encompasses static comfort and dynamic discomfort. Static comfort is associated with ingress, room for the body, seat support and seat adjustment. While dynamic discomfort is attributed to the annoying sound, induced body movement, as well as discordance between sound and vibration. The influence of sound and vibration on perceived ride comfort varies depending on the type of driving scenario (e.g., road profile and speed) and on the type of cars (e.g., CV or EV). Moreover, dynamic discomfort could be controlled by controlling sound and vibration

Human Powered Vehicle Frame Design

This report discusses the Human Powered Vehicle Frame Design senior project’s contributions to the design, manufacture, testing, and competition of the Cal Poly Human Powered Vehicle Club’s 2015 vehicle, Sweet Phoenix. The project’s guiding rules and timeline were dictated by the ASME Human Powered Vehicle Challenge (HPVC), held in April 2015. The Club sought to improve upon its previous vehicle, Aria, which suffered from a range of faults including a catastrophic structural failure at the 2014 HPVC. Largely in response to this failure, the Frame Design project’s major focus was Sweet Phoenix’s frame, from concept to manufacturing. During the design process in the Spring and Fall of 2014, several other issues were tackled in order to define the frame’s design parameters. These secondary efforts included the fairing shape, vehicle stability requirements, handling characteristics, and rider ergonomics. A handling prototype was constructed in late Fall 2014, which successfully validated the solutions to these secondary requirements before the final design was constructed. Ultimately, Sweet Phoenix’s frame is a hybrid design – a composite monocoque fairing to which several weldments are mechanically fastened. The team used extensive finite element analysis to evaluate structural properties for both of these frame subsystems during the final development stages. Sweet Phoenix was produced during the Winter quarter of 2015, with much physical help from the HPV Club members and financial support from several sponsors. The production effort was quite successful, in part thanks to two significant manufacturing improvements – sponsored out-of-house machining of the fairing tools, and a frame-to-fairing alignment jig. The vehicle’s construction quality was recognized at HPVC with a “Best Craftsmanship” award. Testing of the final vehicle revealed very low stiffness of the weldments’ fairing mounts, which was resolved by adding additional bracing locations to the fairing. In addition, the team discovered several drivetrain-related issues that were attacked with numerous attempted solutions, but were not solved prior to HPVC. The drivetrain also contributed to localized delamination of the fairing near a chain idler pulley mount. Unfortunately, these drivetrain issues resulted in several broken chains and poor performance in the acceleration-heavy Endurance Event at HPVC. On the other hand, Sweet Phoenix placed 1st in Design and Men’s Sprint, both satisfying results for the Club, and the Frame Design project was an overall success

Doctor of Philosophy

dissertationSlips and falls during egress from heavy truck cabs are a major contributor to injury and disability for truck drivers. A large-scale laboratory study was conducted to quantify the dynamics of ingress/egress (IE) for Class 7 and 8 commercial truck cabs. A simulated truck cab was constructed in a laboratory allowing manipulation of many geometric variables affecting ingress and egress. Experienced commercial truck drivers were recruited to participate. Subjective responses and anthropometric information for all participants were obtained along with detailed biomechanical data, including whole-body kinematics and reaction forces on the ground, steps, and handholds. This study involves three-dimensional reconstruction of truck driver egress motions, detailed analysis of spatiotemporal parameters and driver behaviors (i.e., IE tactics), as well as a description of access system egress cycles and methods of analyses. In addition, the influence of cab design and driver anthropometric and behavioral factors on biomechanical parameters are investigated. This research also provides a detailed quantitative description of the driver interaction with the cab elements (steps and handholds) and presents valuable insight into the dynamics of cab egress that will allow for a more accurate definition of etiological risk factors for slipping during truck cab egress. In summary, driver biomechanics largely depends on their interaction with the cab, tactics, foot behaviors, and the quality of contact with the steps. In general, during egress, study participants used the right handhold most frequently, followed by the door handle and then the steering wheel. Findings from this research also indicated that a portion of drivers performed egress facing away from the cab and given the prevalence of high body mass index (BMI) among this population, handhold and step location and design should incorporate the base of support (BoS) and stability metric calculations to allow such population for proper "footing" and allow for their center of mass (CoM) to be as close to the truck as possible in the event the drivers utilized the facing away egress tactic. Finally, BMI is a factor that has been associated as an indicator of increased level of risk. Therefore, driver training should include opportunities to get the drivers' weight lowered and fitness level increased. Additionally, drivers may also benefit from stability and strength training as stair stepping is physically more demanding and requires more stability when compared to walking

Vehicle ergonomics and older drivers

There is a growing population of older people around the world and the population of older drivers is increasing in parallel. UK government figures in 2012 reported that there were more than 15 million people with a driving license aged over 60; more than 1 million of these were over 80. The aim of this thesis is to determine the requirements of older users for an improved driving experience leading to recommendations for the automotive industry. Initially it was necessary to understand some of the key issues concerning the driving experiences of older drivers; therefore a questionnaire survey of drivers of all ages (n=903) was conducted supplemented by interviews with drivers aged ≥ 65 years (n=15). Areas covered included: musculoskeletal symptoms, the vehicle seat, driving performance and driving behaviour. Respondents reported that they were dissatisfied with adjusting specific seat features, for example the head rest height and distance from the head; females reported more difficulty than males. Reaching and pulling the boot door down to close was difficult for 12% of older females. Older males and females also reported more difficulties with parallel parking and driving on a foggy day than younger drivers (p<0.01). Nearly half of the sample (47%) reported that other drivers lights restrict their vision when driving at night. An in depth study was conducted to compare participants own vehicle (familiar) and a test vehicle (unfamiliar) to understand how design of the vehicle cab impacts on posture, comfort, health and wellbeing in older drivers (n=47, ≥50 years). The study involved functional performance assessments, seat set-up process evaluation (observations and postural analysis), ergonomics and emotional design based evaluations of car seat controls. Many issues were identified related to the seat controls such as operating, accessing, reaching and finding, particularly for the head rest height and lumbar support adjustments. Approximately 40% of the participants had difficulty turning their head and body around to adjust the head rest height, and the majority of these were over 80. This led to a series of workshops (including a participatory design exercise) with 18 participants (4 groups, ≥ 65 years).The aim was to explore the optimum positioning and operation of controls for older drivers. This research has provided foundational data and makes design recommendations for the automotive industry with a focus on making seat controls more inclusive (operation, location, type, size, colour and materials) and meet the requirements of older drivers

Acceleration

Human responses to linear sustained and rotary acceleration, zero and reduced gravity environments, and impact in manned space fligh

Advanced extravehicular activity systems requirements definition study. Phase 2: Extravehicular activity at a lunar base

The focus is on Extravehicular Activity (EVA) systems requirements definition for an advanced space mission: remote-from-main base EVA on the Moon. The lunar environment, biomedical considerations, appropriate hardware design criteria, hardware and interface requirements, and key technical issues for advanced lunar EVA were examined. Six remote EVA scenarios (three nominal operations and three contingency situations) were developed in considerable detail

Cerberus : a human powered vehicle

A recumbent trike was designed and built for the ASME Human Powered Vehicle Challenge held at San Jose State University in April of 2013. The vehicle was designed to be low cost for use by commuters and as primary transportation in developing countries. The vehicle placed 11th overall in the competition out of 29 teams, and scored 8th in the innovation event, which was its best ranking out of the 5 individual events

Pilot compartment airbag restraint program Final report

Computerized and manned spacecraft and aircraft simulator impact testing of air cushion elastic restraint system