Enhanced Bézier curve-based trajectory planning for high-altitude autonomous trucks

by Du Chigan, Jianbei Liu, Yang Zhao, Jianyou Zhao

Highway freight transport is the backbone of Tibet’s logistics network, accounting for 76.4% of regional freight movement (Tibet Bureau of Statistics, 2024). Challenging alpine road conditions—characterized by steep grades, sharp curves, and narrow lanes—combine with the substantial dimensions of heavy trucks to create significant operational difficulties. Autonomous truck development offers a potential solution; however, their trajectory planning algorithms exhibit limitations in high-altitude environments. To address these challenges, we propose a novel trajectory planning method using quartic Bézier curves. These 4th-order parametric curves provide G² continuity. Our approach integrates speed profiles into a three-dimensional curve representation and employs a two-phase optimization process to ensure safety and efficiency. Simulation results demonstrate the method’s effectiveness in maintaining truck stability while enabling responsive maneuvering under Tibet’s demanding road conditions.

Development and Validation of a Nomogram for Predicting Oral Frailty Risk in Elderly Patients With Ischaemic Stroke

ABSTRACT

Aim

To develop and validate a risk prediction model for oral frailty in elderly patients with ischaemic stroke.

Design

A cross-sectional study.

Methods

A temporal cohort of 633 elderly isachemic stroke patients from May 2024 to February 2025 was chronologically divided into a training set (n = 443) and validation set (n = 190). Participants were classified into oral frailty and non-oral frailty groups based on the Oral Frailty Index-8. In the training set, feature selection combined least absolute shrinkage and selection operator regression and random forest recursive feature elimination, followed by Nomogram Construction via Binary Logistic Regression. The model underwent internal validation using bootstrap resampling, and its generalizability was assessed with the validation set. The model was comprehensively evaluated using Receiver Operating Characteristic (ROC) curves, the Hosmer-Lemeshow Test, Calibration Plots, and Decision Curve Analysis (DCA).

Results

In both the training and validation sets, the prevalence of oral frailty among elderly ischaemic stroke patients was 63.2% and 62.1%, respectively. Wearing dentures, tooth brushing frequency, dry mouth symptoms, chewing difficulty, swallowing function, oral health literacy, and oral health status were identified as significant predictors of oral frailty. ROC analysis demonstrated strong discriminative ability of the nomogram. The Hosmer-Lemeshow Test confirmed model consistency, and the calibration curve indicated excellent and stable calibration performance. DCA revealed that the model provided significant net clinical benefit in clinical practice. This free, interactive dynamic nomogram is accessible at: https://xiaowen.shinyapps.io/dynnomapp/.

Conclusion

This study presents a reliable, accessible model to assess oral frailty risk in elderly ischaemic stroke patients, facilitating clinical identification of high-risk individuals and providing a scientific foundation for oral health interventions.

Relevance to Clinical Practice

The nomogram helps healthcare professionals identify high-risk patients, understand risk factors, and improve oral health management.

Reporting Method

TRIPOD-AI checklist.

Patient or Public Contribution

No patient or public contribution.