101 research outputs found
Shared Control Based on Extended Lipschitz Analysis With Application to Human-Superlimb Collaboration
This paper presents a quantitative method to construct voluntary manual
control and sensor-based reactive control in human-robot collaboration based on
Lipschitz conditions. To collaborate with a human, the robot observes the
human's motions and predicts a desired action. This predictor is constructed
from data of human demonstrations observed through the robot's sensors.
Analysis of demonstration data based on Lipschitz quotients evaluates a)
whether the desired action is predictable and b) to what extent the action is
predictable. If the quotients are low for all the input-output pairs of
demonstration data, a predictor can be constructed with a smooth function. In
dealing with human demonstration data, however, the Lipschitz quotients tend to
be very high in some situations due to the discrepancy between the information
that humans use and the one robots can obtain. This paper a) presents a method
for seeking missing information or a new variable that can lower the Lipschitz
quotients by adding the new variable to the input space, and b) constructs a
human-robot shared control system based on the Lipschitz analysis. Those
predictable situations are assigned to the robot's reactive control, while
human voluntary control is assigned to those situations where the Lipschitz
quotients are high even after the new variable is added. The latter situations
are deemed unpredictable and are rendered to the human. This human-robot shared
control method is applied to assist hemiplegic patients in a bimanual eating
task with a Supernumerary Robotic Limb, which works in concert with an
unaffected functional hand
Kernel Exponential Family Estimation via Doubly Dual Embedding
We investigate penalized maximum log-likelihood estimation for exponential
family distributions whose natural parameter resides in a reproducing kernel
Hilbert space. Key to our approach is a novel technique, doubly dual embedding,
that avoids computation of the partition function. This technique also allows
the development of a flexible sampling strategy that amortizes the cost of
Monte-Carlo sampling in the inference stage. The resulting estimator can be
easily generalized to kernel conditional exponential families. We establish a
connection between kernel exponential family estimation and MMD-GANs, revealing
a new perspective for understanding GANs. Compared to the score matching based
estimators, the proposed method improves both memory and time efficiency while
enjoying stronger statistical properties, such as fully capturing smoothness in
its statistical convergence rate while the score matching estimator appears to
saturate. Finally, we show that the proposed estimator empirically outperforms
state-of-the-artComment: 22 pages, 20 figures; AISTATS 201
- …