1,720,999 research outputs found
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
A wired actuated elbow for human prosthesis
No full textThe mechatronic solutions used in robotic field are more and more used in other areas. Conspicuous research teams are working on arm prosthesis, investigating and developing new mechanical architecture and actuator. The mean aspect is to set up mechanical devices, actuators and energy supply. This paper presents a new mechanical elbow to install on artificial arm for human prosthesis. The device is based on 3 hydraulic actuators connected through some wires to the following forearm components. A complex and optimized path of wires makes actuators work with almost constant linearity between extensions of pistons and flexion-extension and pronation-supination angles. A kinematic 3D virtual model is presented at a second step of geometrical optimization. The authors decided to use redundant actuators, 3 instead of 2, to modulate the mechanical compliance of the artificial arm depending on the kind of operation the patient will wish perform. Moreover, in parallel, the authors are working with the third piston that collaborates with the others to optimize the volume and minimize the stresse
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
Design and analysis of a tendon-driven 2 DOF elbow prosthesis hybrid mechanism
No full textThis paper presents a new mechanical architecturefor elbow powered myoelectric
prostheses. New requirements for active prostheses are energetic autonomy, low production
cost and human like behavior. On the scientific panorama very few examples of parallel
device are available. We show an alternative device, with a simple mechanical hardware, to
simulate the movements and the dynamic of human elbow. We investigated on wires used
like tendons in mechanical elbow prostheses. The wire transmission architecture allows two
linear actuators to control the motion of the forearm along two degrees of freedom in an
enhanced work volume. The device, indeed, is designed to provide in the same mechanism
flexion/extension and pronation/supination movement, which are usually decoupled in elbow
and wrist mechanisms in usual commercial devices
Self Calibrating Wearable Active Running Asymmetry Measurement and Correction
No full textWe present a novel self-calibrating wearable device to improve running training by active vibro feedback. The system consists of a pair of spandex shorts embedding: a processor unit, 2 three-axial accelerometers, 2 vibro motors, a SD card reader\writer module and a real time clock. Two supplementary wireless accelerometers are located on the shoes. We present an algorithm to compute gait asymmetry from the four sensors data. The main novelty is the auto calibration algorithm which uses principal component analysis on each sensor based on kinematic assumptions. The system provides two important advantages: data logging and real time active correction. The active correction is performed sending signals to the user in real time via vibrations cells (rumble feedback). The vibration signals are sent to the specific leg and its intensity is proportional to the entity of required correction. This training system for running can be very useful to athletes and to sport medicine in order to improve speed, posture, fatigue and reduce joints osteoarthrotic problem
Augmented reality for sailing: a comparative study of head stabilized vs boat stabilized visualization data for wind and bearing angle
Full text linkThe wind has been a natural and renewable resource used for professional and recreational maritime transportation of small and large vessels since human history. Sailing is making a comeback due to the growing focus on sustainability, accelerated by the recent global energy crisis. Seafarers rely on wind and bearing angle visualization to navigate efficiently and safely, thanks to the use of sensors and compasses. This paper focuses on Augmented Reality in Head-Mounted Displays visualization of wind and bearing angle data. We analyzed the literature and generated a heatmap of the used areas in the user’s field of view. Second, we designed and implemented two interfaces that use two different visualization techniques: Boat Stabilized (BS) and Head Stabilized (HS). We compared them in between the subject experiment (N = 44), using a simulated Virtual Reality simulator of the sailing scenario. The user’s primary task is wind events recognition, while obstacles (buoys) detection is secondary. We measured both task errors and reaction time, and submit NASA RTLX, SUS, UEQ, and visive auditive and kinesthetic (VAK) questionnaires. We found that BS has a significantly lower reaction time and better usability in the primary and secondary tasks. Both visualization techniques have similar users perceived cognitive load and user experience evaluation. VAK test showed that BS is better for kinaesthetic types and HS is better for visual types
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