SOCIETY OF AUTOMOTIVE ENGINEERS, INC. Two Pennsylvania Plaza, New York, N. Y. 10001 Providing Ride Comfort for the Operator of Off-Highway Vehicles Garth 0. Hall Universal Oil Products Co. soc OF AUTOMOTIVE ENGINEERS National Farm, Construction and Industrial Machinery Meeting Milwaukee, Wis. September 8-11,1969 690567 Downloaded from SAE International by University of New South Wales, Monday, August 20, 2018690567 Providing Ride Comfort for the Operator of Off Highway Vehicles Garth 0. Hall Universal Oil Products Co. PROVIDING RIDE COMFORT for the operators of off-highway vehicles is a continuing task. Comfort is a relative term and has been described as a feeling of well being or satisfaction with one's environment. As a result, a vehicle operator's impression ofacceptable ride comfort may be altered due to improvements in other environmental factors such as noise level, temperature con­ trol, etc. The performacne of many types of off-highway vehicles is increasing. When operator comfort becomes a limiting factor, improvements in this area are required to maintain comfort and also increase productivity. If ride comfort is to be optimized for the vibration en­ vironment which can exist on off-highway vehicles, it will require the combined efforts of the designers who work with items associated with the operator-vehicle interface as well as the research specialists in this area. This requires some general understanding of ride comfort. The purpose of this paper is to review and update this general understanding of the ride comfort problem. The approach of the paper will be to: 1. Review the ride comfort problem 2. Describe how ride comfort can be provided by: (a) Considering the solutions available. (b) Discussing the evaluation methods which are used. THE RIDE COMFORT PROBLEM The ride vibration environment for a vehicle operator is generated by the interaction of the components of the system shown in Fig. 1. Providing ride comfort for the oper­ ator in this environment means control must be exercised The ride comfort problem is reviewed. Some of the solutions to the problem are discussed together with evalua-OPERATOR 1 O/V INTERFACE VEHICLE I V/T INTERFACE TERRAIN Fig. 1 - The ride vibration system over one or more components of the system to limit ride vibrations to acceptable levels. As the system is considered for the off-highway vehicle it becomes apparent that most of the components are not within the control of those studying the ride comfort prob­ lem. The terrain, for example, by the very classification "off- highway" includes naturally occurring profiles and profiles modified for purposes other than travel. The variations pos­ sible seem so great that most ride comfort investigators have - considered only periodic profiles. However, statistical techniques are now being used to define terrain profiles. tion methods which insure proper matching of the dynamic characteristics of seat suspensions to the vehicle. ABSTRACT Downloaded from SAE International by University of New South Wales, Monday, August 20, 20182 10 A g,0 ,-2 z 10 2.0> , \2.0 -o V > 2.0 2.1N V f "^ 0 ^ , *.,1 ?. \ \ V \ ^ \ V \ 100r MAX. PEAK = 100 % Fig. 2 10 .01 .02 .05 .1 .2 .5 1.0 SPATIAL FREQUENCY n(~/FT) Spectral density curves of terrain surfaces Matthews (1)* and Van Deusen (2) have listed spectral dens­ ity curves for various terrain surfaces. Siemens (3) has sum­ marized the curves (Fig. 2) and pointed out they are of the type called white noise. If the terrain is traversed at a constant speed, the units can be multiplied by the velocity to get cps. The interesting points here are that the distri­ butions plot as straight lines which can be defined rather simply, and all the lines have essentially the same slope. This is significant, for many types of terrain can be specified by a simple expression and simulated for computer evalua­ tion by a white noise gen