Technical Awards : 2021 JSAE Award The Outstanding Technical Paper Award - An Approach to Exploring Vehicle Motion to Enhance Ride Quality of PassengerFig.12 Vehicle and passenger motion of actual vehicle test: Every data curve was averaged (n=5).NISSAN TECHNICAL REVIEW No.88 (2022)Fig.13 Passenger upper body posture transition: Earlier motion generation is required for terminal posture control, then needs quick initial motion, too.5. Considerations for exploring ride qualitypredict the vehicle motion because the passenger can only view the external environment through the surrounding view. Therefore, the test environment should be similar to that in the passive motion evaluation. The transitions in the passenger posture were estimated using the movement detected by the displacement sensor attached to the rear of the neck.The test results are presented in Fig. 12 in a manner that corresponds to the calculation examples (Fig. 11). It can be considered that the reproducibility of the acceleration space was ensured. The deviation between the passenger posture transition and the calculated value (the results in the fi gure were multiplied with a coeffi cient of 2.0) is attributed to the differences between individual evaluators, as the passenger model characteristic values in Fig. 9 were used for the calculation (the values differ by a factor of approximately 2 for some data within the quartile range). It is judged that the relative relationship between the specifi cations is in-line with the predictions based on the calculations.In the subjective evaluation, it “seems that the motion is smooth while the body posture transition is large” with specifi cation V0, whereas it “seems that the body roll posture transition is small” with specifi cation R1 (in which the body roll angle acceleration is suppressed). In other words, the result that “the body seems to have moved along with the vehicle motion” was obtained. However, in the case of specifi cation R2 (in which additional terminal constraints for the roll posture are implemented), the evaluation “movement at the early stage of the motion was large compared to V0” was obtained. In addition, the evaluation that “while the high-frequency motion was somewhat noticeable, it was possible to feel the load reduction due to the suppressed body motion” was obtained for the “body roll suppression” terminal condition, with the objective of maintaining body posture. In summary, it was possible to parameterize the ride quality in terms of both the measurements and subjective evaluations using the passenger passive motion design. In the passenger body model, increasing the degree of freedom (such as by separately defi ning the head portion) is possible. However, this will make it diffi cult to determine the appropriate model characteristic values, such as the stiffness at the neck portion, even if the scope of the model is limited to passive motion. It is assumed that passengers will perform various activities and be in various states in the vehicle. Therefore, in addition to addressing the complexity of the passenger model, determining the settings of the characteristic values of the model needs to be resolved in future research.However, the motion perceived by the passenger cannot be mechanically calculated based on the body model. Thus, it may be important to add a model that represents the human inner sensory characteristics such that the evaluation function is confi gured using the actual perception values. Fig. 13 shows the body behavior (calculated values) under the specifi cations, where the body roll angle acceleration is used as the evaluation function. R1 does not include terminal constraints, whereas R2 has terminal constraints. Compared to specifi cation R1, specifi cation R2 causes more lateral movements during the intermediate test time. It is clear that the body roll movement must occur early to control the body behavior at the terminal. Although the roll motion is suppressed, the translational acceleration is increased. Therefore, the mechanism of the perceptual recognition of translational and rotational motions must be considered.The degree of freedom of the motion design depends on the limitations in the form of the evaluation function. The variables that can be incorporated are typically limited to a combination of quadratic forms. In addition, in the travel scene expanded to multiple control inputs, 76115
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