uncertainty representation
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2021 ◽  
Author(s):  
Balazs B Ujfalussy ◽  
Gergő Orbán

Efficient planning in complex environments requires that uncertainty associated with current inferences and possible consequences of forthcoming actions is represented. Representation of uncertainty has been established in sensory systems during simple perceptual decision making tasks but it remains unclear if complex cognitive computations such as planning and navigation are also supported by probabilistic neural representations. Here we capitalized on gradually changing uncertainty along planned motion trajectories during hippocampal theta sequences to capture signatures of uncertainty representation in population responses. In contrast with prominent theories, we found no evidence of encoding parameters of probability distributions in the momentary population activity recorded in an open-field navigation task in rats. Instead, uncertainty was encoded sequentially by sampling motion trajectories randomly in subsequent theta cycles from the distribution of potential trajectories. Our analysis is the first to demonstrate that the hippocampus is well equipped to contribute to optimal planning by representing uncertainty.


Robotica ◽  
2021 ◽  
pp. 1-19
Author(s):  
Timothy D. Barfoot ◽  
James R. Forbes ◽  
Gabriele M. T. D’Eleuterio

Abstract Robotics and computer vision problems commonly require handling rigid-body motions comprising translation and rotation – together referred to as pose. In some situations, a vectorial parameterization of pose can be useful, where elements of a vector space are surjectively mapped to a matrix Lie group. For example, these vectorial representations can be employed for optimization as well as uncertainty representation on groups. The most common mapping is the matrix exponential, which maps elements of a Lie algebra onto the associated Lie group. However, this choice is not unique. It has been previously shown how to characterize all such vectorial parameterizations for SO(3), the group of rotations. Some results are also known for the group of poses, where it is possible to build a family of vectorial mappings that includes the matrix exponential as well as the Cayley transformation. We extend what is known for these pose mappings to the $4 \times 4$ representation common in robotics and also demonstrate three different examples of the proposed pose mappings: (i) pose interpolation, (ii) pose servoing control, and (iii) pose estimation in a pointcloud alignment problem. In the pointcloud alignment problem, our results lead to a new algorithm based on the Cayley transformation, which we call CayPer.


2021 ◽  
Vol 11 (4) ◽  
pp. 1883
Author(s):  
Guohai Chen ◽  
Tong Wang ◽  
Congda Lu ◽  
Yuanshan Yang ◽  
Lin Li ◽  
...  

Due to manufacturing errors, inaccurate measurement and working conditions changes, there are many uncertainties in laminated composite cylindrical shells, which causes the variation of vibration characteristics, and has an important influence on the overall performance. Therefore, an uncertainty representation methodology of natural frequency for laminated composite cylindrical shells is proposed, which considers probabilistic and interval variables simultaneously. The input interval variables are converted into a probabilistic density function or cumulative distribution function based on a four statistical moments method, and a unified probabilistic uncertainty analysis method is proposed to calculate the uncertainty of natural frequency. An adaptive Kriging surrogate model considering probabilistic uncertainty variables is established to accurately represent the natural frequency of laminated composite cylindrical shells. Finally, the dimensionless natural frequency of three-layer, five-layer and seven-layer laminated composite cylindrical shells with uncertainty input parameters is accurately represented. Compared with the Monte Carlo Simulation results, the mean error and standard deviation error are reduced to less than 0.07% and 4.7%, respectively, and the execution number of calculation function is significantly decreased, which fully proves the effectiveness of the proposed method.


Author(s):  
Javier Troya ◽  
Nathalie Moreno ◽  
Manuel F. Bertoa ◽  
Antonio Vallecillo

2021 ◽  
Vol 402 ◽  
pp. 78-104 ◽  
Author(s):  
Fernando Matía ◽  
Víctor Jiménez ◽  
Biel P. Alvarado ◽  
Rodolfo Haber

Author(s):  
Nadescha Trudel ◽  
Jacqueline Scholl ◽  
Miriam C. Klein-Flügge ◽  
Elsa Fouragnan ◽  
Lev Tankelevitch ◽  
...  

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