1,721,381 research outputs found
Fotografía UDBC029742
No full textFotografía del ejemplar Reina, G. 118, determinado como Anthurium sp
Fotografía UDBC029734
No full textFotografía del ejemplar Reina, G. 117, determinado como Anthurium sp
Locomotion Performance Evaluation of an All-Terrain Rover
No full textIn the last few years, mobile robots are increasingly being used in natural outdoor terrain for applications such as forestry, mining, rescuing, precision farming, and planetary exploration. Future tasks will require robotic vehicles to travel over longer distances through challenging terrain, with limited human supervision. To accomplish this objective, a higher degree of mobility will be primarily required, ensuring, at the same time, the safety of the vehicle. In this paper, a robot with advanced mobility features is presented and its locomotion performance is evaluated, following an analytical approach. The proposed vehicle features an independently controlled 4-wheel-drive/4-wheel-steer architecture that allows the robot to perform maneuvers such as turn-on-the-spot and crab motion. It also employs a passive rocker-type suspension system, improving the ability to traverse uneven terrain, while ensuring good traction performance. An overview of modeling techniques for rover-like vehicles is introduced. First, a method for formulating a classical kinematic model of an articulated vehicle is presented. Next, a method for expressing a quasi-static model of forces acting on the robot is described. Note that quasi-static models are appropriate due to the relative low speed and acceleration of those vehicles. Two optimization methods are also proposed to control the rover's motion, minimizing slip and power consumption, respectively. These models are used to reproduce the behavior of the robot in typical obstacle-climbing scenarios, pointing to the advantages compared with conventional architectures
Corrigendum to: Modelling and handling dynamics of a wind-driven vehicle (Vehicle System Dynamics, (2019), 57, 5, (697-720), 10.1080/00423114.2018.1479529)
No full textWhen the above article was first published online, Figure 3 and Figure 4 were erroneously interchanged. This has now been corrected online. The authors apologise for this error
Efficient Power-Split Powertrain for Full Electric Vehicles
No full textElectric vehicles are typically employed in highly-variable operating conditions, especially during city drive. The variability in speed and torque results in suboptimal efficiency of the drive motor. However, recent technological advances in new embedded processing units and power electronics open the way to the adoption of novel efficient control strategies of the electric powertrain. This paper proposes an architecture that in contrast to the use of a single drive electric motor employs two drive motors of smaller size combined through a planetary gear. This power-split full-electric architecture ensures both drive motors to operate in their optimal working range resulting in a higher overall efficiency. A parametric optimization is performed showing an increase in the average efficiency of about 7% with respect to a single motor for the Artemis urban cycle
An adaptive suspension system for planetary rovers
No full textThis paper presents an innovative suspension system with variable wheel camber to improve mobility of robots on rough-terrain. The system is optimized for planetary rovers that employ conventional rocker-type suspensions. The main advantage of the proposed system is that each wheel keeps an upright posture as the suspension system adapts to terrain unevenness, maximizing tractive and climbing performance, and reducing energy consumption. The synthesis of the variable camber mechanism is described along with details of the mechanical design, showing the feasibility of this solutio
Pavement distress detection and avoidance for intelligent vehicles
No full textPavement distresses and potholes represent road hazards that can cause accidents and damages to vehicles. The latter may vary from a simple flat tyre to serious failures of the suspension system, and in extreme cases to collisions with third-party vehicles and even endanger passengers' lives. The primary scientific aim of this study is to investigate the problem of road hazard detection for driving assistance purposes, towards the final goal of implementing such a technology on future intelligent vehicles. The proposed approach uses a depth sensor to generate an environment representation in terms of 3D point cloud that is then processed by a normal vector-based analysis and presented to the driver in the form of a traversability grid. Even small irregularities of the road surface can be successfully detected. This information can be used either to implement driver warning systems or to generate, using a cost-to-go planning method, optimal trajectories towards safe regions of the carriageway. The effectiveness of this approach is demonstrated on real road data acquired during an experimental campaign. Normal analysis and path generation are performed in post-analysis. This approach has been demonstrated to be promising and may help to drastically reduce fatal traffic casualties, as a high percentage of road accidents are related to pavement distress
On wind-driven land vehicles
No full textThis paper deals with the study of a land-yacht, that is a ground vehicle propelled by wind energy. There is a large interest in exploring alternative source of energy for propulsion and wind energy could be a feasible solution being totally green, available and free. The idea envisaged by a land-yacht is that of using one or several flexible or rigid vertical wing-sails to produce a thrust-force, which can eventually generate a higher travel velocity than its prevailing wind. A model of a three-wheel land-yacht is presented capturing the main dynamic and aerodynamic aspects of the system behaviour. Simulations are included showing how environment conditions, i.e. wind intensity and direction, influence the vehicle response and performance. In view of a robotic embodiment of the vehicle, a controller of the sail trim angle and front wheel steer angle is also discussed for autonomous navigation
On wind-driven land vehicles
No full textThis paper deals with the study of a land-yacht, that is a ground vehicle propelled by wind energy. There is a large interest in exploring alternative source of energy for propulsion and wind energy could be a feasible solution being totally green, available and free. The idea envisaged by a land-yacht is that of using one or several flexible or rigid vertical wing-sails to produce a thrust-force, which can eventually generate a higher travel velocity than its prevailing wind. A model of a three-wheel land-yacht is presented capturing the main dynamic and aerodynamic aspects of the system behaviour. Simulations are included showing how environment conditions, i.e. wind intensity and direction, influence the vehicle response and performance. In view of a robotic embodiment of the vehicle, a controller of the sail trim angle and front wheel steer angle is also discussed for autonomous navigation
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