RESUMO
In view of the need for emergency steering to avoid collision when the vehicle is in a dangerous scene, and the stability control of the vehicle during collision avoidance. This paper proposes a planning and control framework. A path planner considering the kinematics and dynamics of the vehicle system is used to formulate the safe driving path under emergency conditions. LQR lateral control algorithm is designed to calculate the output steering wheel angle. On this basis, adaptive MPC control algorithm and four-wheel braking force distribution control algorithm are designed to achieve coordinated control of vehicle driving stability and collision avoidance safety. The simulation results show that the proposed algorithm can complete the steering collision avoidance task quickly and stably.
RESUMO
The intervention time of stability control system is determined by stability judgment, which is the basis of vehicle stability control. According to the different working conditions of the vehicle, we construct the phase plane of the vehicle's sideslip angle and sideslip angular velocity, and establish the sample dataset of the stable region of the different phase planes. To reduce the complexity of phase plane stable region division and avoid large amount of data, we established the support vector regression (SVR) model, and realized the automatic regression of dynamic stable region. The testing of the test set shows that the model established in this paper has strong generalization ability. We designed a direct yaw-moment control (DYC) stability controller based on linear time-varying model predictive control (LTV-MPC). The influence of key factors such as centroid position and road adhesion coefficient on the stable region is analyzed through phase diagram. The effectiveness of the stability judgment and control algorithm is verified by simulation tests.
RESUMO
OBJECTIVES: Cross-language studies, as reflected by the scalp-recorded frequency-following response (FFR) to voice pitch, have shown the influence of dominant linguistic environments on the encoding of voice pitch at the brainstem level in normal-hearing adults. Research questions that remained unanswered included the characteristics of the FFR to voice pitch in neonates during their immediate postnatal period and the relative contributions of the biological capacities present at birth versus the influence of the listener's postnatal linguistic experience. The purpose of this study was to investigate the characteristics of FFR to voice pitch in neonates during their first few days of life and to examine the relative contributions of the "biological capacity" versus "linguistic experience" influences on pitch processing in the human brainstem. DESIGN: Twelve American neonates (five males, 1-3 days old) and 12 Chinese neonates (seven males, 1-3 days old) were recruited to examine the characteristics of the FFRs during their immediate postnatal days of life. Twelve American adults (three males; age: mean ± SD = 24.6 ± 3.0 yr) and 12 Chinese adults (six males; age: mean ± SD = 25.3 ± 2.6 yr) were also recruited to determine the relative contributions of biological and linguistic influences. A Chinese monosyllable that mimics the English vowel /i/ with a rising pitch (117-166 Hz) was used to elicit the FFR to voice pitch in all participants. RESULTS: Two-way analysis of variance (i.e., the language [English versus Chinese] and age [neonate versus adult] factors) showed a significant difference in Pitch Strength for language (p = 0.035, F = 4.716). A post hoc Tukey-Kramer analysis further demonstrated that Chinese adults had significantly larger Pitch Strength values than Chinese neonates (p = 0.024). This finding, coupled with the fact that American neonates and American adults had comparable Pitch Strength values, supported the linguistic experience model. On the other hand, Pitch Strength obtained from the American neonates, American adults, and Chinese neonates were not significantly different from each other, supporting the biological capacity model. CONCLUSIONS: This study demonstrated an early maturation of voice-pitch processing in neonates starting from 1 to 3 days after birth and a significant effect of linguistic experience on the neural processing of voice pitch at the brainstem level. These findings provide a significant conceptual advancement and a basis for further examination of developmental maturation of subcortical representation of speech features, such as pitch, timing, and harmonics. These findings can also be used to help identify neonates at risk for delays in voice-pitch perception and provide new directions for preventive and therapeutic interventions for patients with central auditory processing deficits, hearing loss, and other types of communication disorders.