scholarly journals Real-time obstacle avoidance using harmonic potential functions

2002 ◽  
Author(s):  
J.-O. Kim ◽  
P. Khosla
Keyword(s):  
Real Time ◽  
Obstacle Avoidance ◽  
Potential Functions ◽  
Harmonic Potential

Real-time obstacle avoidance for multiple mobile robots

Robotica ◽  
2009 ◽  
Vol 27 (2) ◽  
pp. 189-198 ◽  
Author(s):  
Farbod Fahimi ◽  
C. Nataraj ◽  
Hashem Ashrafiuon
Keyword(s):  
Mobile Robots ◽  
Real Time ◽  
Obstacle Avoidance ◽  
Panel Method ◽  
The Other ◽  
Harmonic Potential ◽  
Current Position ◽  
Multiple Mobile Robots ◽  
Moving Obstacles ◽  
Harmonic Potential Field

SUMMARYAn efficient, simple, and practical real time path planning method for multiple mobile robots in dynamic environments is introduced. Harmonic potential functions are utilized along with the panel method known in fluid mechanics. First, a complement to the traditional panel method is introduced to generate a more effective harmonic potential field for obstacle avoidance in dynamically changing environments. Second, a group of mobile robots working in an environment containing stationary and moving obstacles is considered. Each robot is assigned to move from its current position to a goal position. The group is not forced to maintain a formation during the motion. Every robot considers the other robots of the group as moving obstacles and hence the physical dimensions of the robots are also taken into account. The path of each robot is planned based on the changing position of the other robots and the position of stationary and moving obstacles. Finally, the effectiveness of the scheme is shown by modeling an arbitrary number of mobile robots and the theory is validated by several computer simulations and hardware experiments.

Obstacle Avoidance for 2D Hyper-Redundant Manipulators Using Harmonic Potential Functions and the Mode Shape Technique

2001 ◽  
Author(s):  
F. Fahimi ◽  
H. Ashrafiuon ◽  
C. Nataraj
Keyword(s):  
Obstacle Avoidance ◽  
Dimensional Space ◽  
Potential Functions ◽  
Harmonic Potential ◽  
Redundant Manipulators ◽  
Two Dimensional ◽  
Algebraic Equations ◽  
Backbone Curve ◽  
Cluttered Environments ◽  
Fitting Method

Abstract Obstacle avoidance for discrete-link two-dimensional (2D) hyper-redundant manipulators in known environments is considered. The manipulator is divided into two sections, a proximal section that has not entered the space among obstacles and a distal section among the obstacles. Harmonic potential functions were used, in order to avoid local minima in cluttered environments. A modified panel method is used to generate the potential of any arbitrary shaped obstacle in two-dimensional space. An alternative backbone curve concept and an efficient fitting method are introduced to control the trajectory of proximal links. The fitting method is recursive and avoids the complications involved with solving large systems of nonlinear algebraic equations. Combination of the safe path derived from the harmonic potential field and the backbone curve concept leads to an elegant kinematic control strategy that guarantees obstacle avoidance for planar hyper-redundant robotic manipulators.

scholarly journals “Real-time” obstacle avoidance in the absence of primary visual cortex

2009 ◽  
Vol 106 (37) ◽  
pp. 15996-16001 ◽  
Author(s):  
Christopher L. Striemer ◽  
Craig S. Chapman ◽  
Melvyn A. Goodale
Keyword(s):  
Visual Cortex ◽  
Real Time ◽  
Obstacle Avoidance ◽  
Primary Visual Cortex ◽  
Posterior Parietal Cortex ◽  
Dorsal Stream ◽  
Visual Pathways ◽  
Visual Stream ◽  
Reaching Task ◽  
Visual Inputs

When we reach toward objects, we easily avoid potential obstacles located in the workspace. Previous studies suggest that obstacle avoidance relies on mechanisms in the dorsal visual stream in the posterior parietal cortex. One fundamental question that remains unanswered is where the visual inputs to these dorsal-stream mechanisms are coming from. Here, we provide compelling evidence that these mechanisms can operate in “real-time” without direct input from primary visual cortex (V1). In our first experiment, we used a reaching task to demonstrate that an individual with a dense left visual field hemianopia after damage to V1 remained strikingly sensitive to the position of unseen static obstacles placed in his blind field. Importantly, in a second experiment, we showed that his sensitivity to the same obstacles in his blind field was abolished when a short 2-s delay (without vision) was introduced before reach onset. These findings have far-reaching implications, not only for our understanding of the time constraints under which different visual pathways operate, but also in relation to how these seemingly “primitive” subcortical visual pathways can control complex everyday behavior without recourse to conscious vision.

Obstacle avoidance control of a human-in-the-loop mobile robot system using harmonic potential fields

Robotica ◽  
2017 ◽  
Vol 36 (4) ◽  
pp. 463-483 ◽  
Author(s):  
C. Ton ◽  
Z. Kan ◽  
S. S. Mehta
Keyword(s):  
Mobile Robot ◽  
Obstacle Avoidance ◽  
Sliding Mode ◽  
Harmonic Potential ◽  
Control Allocation ◽  
Control Input ◽  
Continuous Control ◽  
Control Effort ◽  
Human In The Loop ◽  
Allocation Function

SUMMARYThis paper considers applications where a human agent is navigating a semi-autonomous mobile robot in an environment with obstacles. The human input to the robot can be based on a desired navigation objective, which may not be known to the robot. Additionally, the semi-autonomous robot can be programmed to ensure obstacle avoidance as it navigates the environment. A shared control architecture can be used to appropriately fuse the human and the autonomy inputs to obtain a net control input that drives the robot. In this paper, an adaptive, near-continuous control allocation function is included in the shared controller, which continuously varies the control effort exerted by the human and the autonomy based on the position of the robot relative to obstacles. The developed control allocation function facilitates the human to freely navigate the robot when away from obstacles, and it causes the autonomy control input to progressively dominate as the robot approaches obstacles. A harmonic potential field-based non-linear sliding mode controller is developed to obtain the autonomy control input for obstacle avoidance. In addition, a robust feed-forward term is included in the autonomy control input to maintain stability in the presence of adverse human inputs, which can be critical in applications such as to prevent collision or roll-over of smart wheelchairs due to erroneous human inputs. Lyapunov-based stability analysis is presented to guarantee finite-time stability of the developed shared controller, i.e., the autonomy guarantees obstacle avoidance as the human navigates the robot. Experimental results are provided to validate the performance of the developed shared controller.

Design of Obstacle Avoidance Detection Based on Substation Intelligent Inspection Robot

2013 ◽  
Vol 748 ◽  
pp. 695-698
Author(s):  
Hai Peng Wang ◽  
Yong Sun ◽  
Peng Xiao ◽  
Yi Qing Luan
Keyword(s):  
Real Time ◽  
Obstacle Avoidance ◽  
Detection System ◽  
Measurement Precision ◽  
Ultrasonic Signal ◽  
System Software ◽  
Ultrasonic Sensors ◽  
Inspection Robot ◽  
High Measurement ◽  
Environmental Requirements

The obstacle avoidance system is an important part of the intelligent inspection robot. According to the special environmental requirements for substation inspection robot, the inspection robot obstacle avoidance detection system was designed. The system takes MCU as the controller core, selects many sets of ultrasonic sensors to detect the obstacle information around the robot, designs the transmitting and receiving circuit of the ultrasonic signal, and completes the system software program. In consideration of the substations effect of EMI to the electronic equipments, when designing circuit, using a large of filter circuit, improve systems anti-interference performance, realize real-time and veracity of measurement. Using on substation shows that the system run steadily, have high measurement precision, its important for improving the robot using on substation.

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