Search Results (7)

Autonomous navigation for micro electric vehicles (micro EVs) operating in semi-structured environments—such as university campuses and industrial parks—requires solutions that are cost-effective, low in complexity, and robust. Traditional autonomous systems often rely on high-definition maps, multi-sensor fusion, or vision-based SLAM, which demand expensive sensors and high computational power. These approaches are often impractical for micro EVs with limited onboard resources. To address this gap, a real-world autonomous navigation system is presented, combining RTK-GNSS and 2D LiDAR with a real-time trajectory scoring algorithm. This configuration enables accurate path following and obstacle avoidance without relying on complex mapping or multi-sensor fusion. This study presents the development and experimental validation of a low-speed autonomous navigation system for a micro electric vehicle based on GNSS-RTK localization and real-time obstacle avoidance. The research achieved the following three primary objectives: (1) the development of a low-level control system for steering, acceleration, and braking; (2) the design of a high-level navigation controller for autonomous path following using GNSS data; and (3) the implementation of real-time obstacle avoidance capabilities. The system employs a scored predicted trajectory algorithm that simultaneously optimizes path-following accuracy and obstacle evasion. A Toyota COMS micro EV was modified for autonomous operation and tested on a closed-loop campus track. Experimental results demonstrated an average lateral deviation of 0.07 m at 10 km/h and 0.12 m at 15 km/h, with heading deviations of approximately 3° and 4°, respectively. Obstacle avoidance tests showed safe maneuvering with a minimum clearance of 1.2 m from obstacles, as configured. The system proved robust against minor GNSS signal degradation, maintaining precise navigation without reliance on complex map building or inertial sensing. The results confirm that GNSS-RTK-based navigation combined with minimal sensing provides an effective and practical solution for autonomous driving in semi-structured environments. Full article

Obstacle circumvention is an important task for community ambulation that is challenging to replicate in research and clinical environments. Omnidirectional treadmills combined with virtual reality (ODT-VR) offer a promising solution, allowing users to change walking direction and speed while walking in large, simulated environments. However, the extent to which such a setup yields circumvention strategies representative of overground walking in the real world (OVG-RW) remains to be determined. This study examined obstacle circumvention strategies in ODT-VR versus OVG-RW and measured how they changed with practice. Fifteen healthy young individuals walked while avoiding an interferer, performing four consecutive blocks of trials per condition. Distance at onset trajectory deviation, minimum distance from the interferer, and walking speed were compared across conditions and blocks. In ODT-VR, larger clearances and slower walking speeds were observed. In contrast, onset distances and proportions of right-side circumvention were similar between conditions. Walking speed increased from the first to the second block exclusively. Results suggest the use of a cautious locomotor behavior while using the ODT-VR setup, with some key features of circumvention strategies being preserved. Although ODT-VR setups offer exciting prospects for research and clinical applications, consideration should be given to the generalizability of findings to the real world. Full article

The International Civil Aviation Organization (ICAO) specifies that in the design phase of instrument flight procedures, an additional clearance may be added to an obstacle when flights are over mountainous terrain. This clearance increase can be up to 100 per cent of the minimum obstacle clearance (MOC). Airspace and instrument flight procedure designers usually face the problem of determining what value should be applied, since setting the maximum value of 100% often implies operational penalties, but there are no standardized criteria to determine lower values. The ICAO PANS-OPS indicates that the additional clearance over obstacles in mountainous areas is caused by two effects, both related to orography and wind speed. The first effect is due to the altimeter indication error. The second one is related to the loss of altitude when an aircraft is exposed to turbulence produced by mountain waves. This paper presents a methodology for determining the additional clearance to be applied over obstacles when, in the flight procedure design phase, the overflight of mountainous terrain is expected. Through this methodology, results have been achieved for the proposal of an appropriate additional clearance. The development of graphs and tables allows us to identify which additional value should be considered in each case. Full article

In performance-based navigation (PBN) procedures with barometric vertical guidance, the effective vertical path angle (VPA) depends on the actual air temperature at the time of approach execution. A very low design temperature could result in an obstacle clearance height (OCH) higher than needed; hence, the airport throughput could be reduced when the cloud ceiling is below the OCH. Conversely, the design of a low temperature higher than is practical could lead to long periods in which the procedure cannot be used. The results of this research show that there is not much difference between the effective VPA for the different low temperatures studied. However, this slight difference, when obstacles penetrating the final approach surface (FAS) exist, usually leads to the approach minima being significantly different from each other. The objective of this study was to analyse the impact of the selected designed low temperatures in PBN procedures with barometric vertical guidance on the OCH/runway throughput and approach periods of use balance. Finally, guidelines on the selection of the minimum designed low temperature are proposed. Full article

The middle and lower reaches of the Yangtze River are the main production area of rapeseed. Small windrowers with two tracks are adopted in this area, which have lower efficiency. With the advancement of large-scale rape planting, medium and large windrowers are urgently needed; however, most medium and large windrowers are wheeled machines which have poor adaptability to sticky soil in rice–rape rotation areas. Therefore, a wheel-track high clearance chassis for rape windrower was developed. Theoretical analysis and simulation of the main performance of this chassis were investigated. Mathematical models of the relationship between the chassis eccentricity and running resistance, uphill and downhill angle and the height of obstacle were established. Then, three-dimensional modeling and dynamic simulations of a wheel-track high clearance chassis of a rape windrower in wet clay soil were carried out based on Pro/E and RecurDyn software. The simulation results indicated that when the chassis ran on flat hard road at the same speed, eccentricity had little effect on average walking speed; the coefficient variation of speed decreased with the increase of eccentricity, while the driving torque and its coefficient variation decreased first and then increased. The minimum driving torque and the coefficient variations were obtained when the eccentricities were 1484 mm and 1584 mm. Field experiments were carried out on two kinds of ground. The results showed that on flat hard road, the speed of the wheel-track high clearance rape windrower was 0~20.22 km/h, the minimum turning radius was 5.965 m; on rice stubble field with 38.7% water content, the working speed was 0~9.12 km/h, the minimum turning radius was 6.498 m, and the climbing angle was over 20°. All parameters of the wheel-track high clearance chassis met the design specifications, and the working efficiency increased over 100% compared with the existing two-tracked rape windrower. A new kind of rape windrower for the middle and lower reaches of the Yangtze River was provided. Full article

Over half of older adult falls are caused by tripping. Many of these trips are likely due to obstacles present on walkways that put older adults or other individuals with low foot clearance at risk. Yet, Minimum Foot Clearance (MFC) values have not been measured in real-world settings and existing methods make it difficult to do so. In this paper, we present the Minimum Foot Clearance Estimation (MFCE) system that includes a device for collecting calibrated video data from pedestrians on outdoor walkways and a computer vision algorithm for estimating MFC values for these individuals. This system is designed to be positioned at ground level next to a walkway to efficiently collect sagittal plane videos of many pedestrians’ feet, which is then processed offline to obtain MFC estimates. Five-hundred frames of video data collected from 50 different pedestrians was used to train (370 frames) and test (130 frames) a convolutional neural network. Finally, data from 10 pedestrians was analyzed manually by three raters and compared to the results of the network. The footwear detection network had an Intersection over Union of 85% and was able to find the bottom of a segmented shoe with a 3-pixel average error. Root Mean Squared (RMS) errors for the manual and automated methods for estimating MFC values were 2.32 mm, and 3.70 mm, respectively. Future work will compare the accuracy of the MFCE system to a gold standard motion capture system and the system will be used to estimate the distribution of MFC values for the population. Full article

Mobile robots are expected to traverse on unstructured terrain, especially uneven terrain, or to climb obstacles or slopes. This paper analyzes one such passively–actively transformable mobile robot that is principally aimed at the above issue. A passive locomotion traverses on a rough and flat terrain; an active reconfiguration with an active suspension. This paper investigates the lateral stability of this mobile robot when it reconfigures itself to adjust its roll angle with the active suspension. The principles and configurations of the robot and its active suspension are presented. To analyze the effects of the suspensions’ inputs on robot stability, a mathematic model of the robot on side slopes is presented. Based on the evaluation method of the stability pyramid theory, an analytical expression representing the relationship between the input of the active suspension (linear actuator length) and stability evaluation index on transverse slopes is obtained. The results show that there is an increase in both the lateral stability and minimum lateral tip-over angle under different ground clearances when adjusting the active inputs. Furthermore, the models presented here provide theoretical references and optimization directions for the design and control of mobile robots with adjustable suspensions. Full article