99 research outputs found
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Design of a Passive Exoskeleton Spine
In this thesis, a passive exoskeleton spine was designed and evaluated by a series of biomechanics simulations. The design objectives were to reduce the human operator’s back muscle efforts and the intervertebral reaction torques during a full range sagittal plane spine flexion/extension. The biomechanics simulations were performed using the OpenSim modeling environment. To manipulate the simulations, a full body musculoskeletal model was created based on the OpenSim gait2354 and “lumbar spine” models. To support flexion and extension of the torso a “push-pull” strategy was proposed by applying external pushing and pulling forces on different locations on the torso. The external forces were optimized via simulations and then a physical exoskeleton prototype was built to evaluate the “push-pull” strategy in vivo. The prototype was tested on three different subjects where the sEMG and inertial data were collected to estimate the muscle force reduction and intervertebral torque reduction. The prototype assisted the users in sagittal plane flexion/extension and reduced the average muscle force and intervertebral reaction torque by an average of 371 N and 29 Nm, respectively
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A novel robotic platform to assist, train, and study head-neck movement
Moving the head-neck freely is an everyday task that a healthy person takes for granted. Such a simple movement, however, may be very challenging for individuals with neurological disorders such as amyotrophic lateral sclerosis. These individuals often do not have enough neck muscle strength to stabilize the head at the upright neutral or to move it in a controlled manner. Static braces are commonly prescribed to these patients. However, these braces often fix the head at a single configuration, which makes them uncomfortable to wear for an extended period of time.
In this thesis, a robotic neck brace is developed. It accommodates three rotations and covers roughly 70% range of motion of the head-neck of a typical able-bodied adult. The hardware is lightweight (1.5 kilogram) and wearable, with a pair of pads and a soft band attached to the shoulders and the forehead, respectively. A parallel mechanism connecting the shoulder pads and the headband was designed to meet the empirical human movement data. This design choice is novel where the parasitic motion (translation of the head) was parameterized and optimized to address misalignment between the robot and the user's head.
A user can control this neck brace to assist intended head-neck movement through input devices, including hand-held joysticks, keyboards, and eye-trackers. This provides a potential solution to remediate head drop. Additionally, this robotic brace is developed into a versatile platform to train and study head-neck movements. The robot was designed to be highly transparent to the user and features different force controllers. Therefore, it can be used to assess the free movement of the head-neck and mimic different interactions between a therapist and a patient. The modalities of this neck brace have been validated with different users. To the best of our knowledge, this robotic neck brace is the first in the literature to assist, train, and study head-neck movements
TSNet-SAC: Leveraging Transformers for Efficient Task Scheduling
In future 6G Mobile Edge Computing (MEC), autopilot systems require the
capability of processing multimodal data with strong interdependencies.
However, traditional heuristic algorithms are inadequate for real-time
scheduling due to their requirement for multiple iterations to derive the
optimal scheme. We propose a novel TSNet-SAC based on Transformer, that
utilizes heuristic algorithms solely to guide the training of TSNet.
Additionally, a Sliding Augment Component (SAC) is introduced to enhance the
robustness and resolve algorithm defects. Furthermore, the Extender component
is designed to handle multi-scale training data and provide network
scalability, enabling TSNet to adapt to different access scenarios. Simulation
demonstrates that TSNet-SAC outperforms existing networks in accuracy and
robustness, achieving superior scheduling-making latency compared to heuristic
algorithms
Toward Learning Human-aligned Cross-domain Robust Models by Countering Misaligned Features
Machine learning has demonstrated remarkable prediction accuracy over i.i.d
data, but the accuracy often drops when tested with data from another
distribution. In this paper, we aim to offer another view of this problem in a
perspective assuming the reason behind this accuracy drop is the reliance of
models on the features that are not aligned well with how a data annotator
considers similar across these two datasets. We refer to these features as
misaligned features. We extend the conventional generalization error bound to a
new one for this setup with the knowledge of how the misaligned features are
associated with the label. Our analysis offers a set of techniques for this
problem, and these techniques are naturally linked to many previous methods in
robust machine learning literature. We also compared the empirical strength of
these methods demonstrated the performance when these previous techniques are
combined, with an implementation available at https://github.com/OoDBag/WRComment: to appear at UAI 202
Foundation Model-oriented Robustness: Robust Image Model Evaluation with Pretrained Models
Machine learning has demonstrated remarkable performance over finite
datasets, yet whether the scores over the fixed benchmarks can sufficiently
indicate the model's performance in the real world is still in discussion. In
reality, an ideal robust model will probably behave similarly to the oracle
(e.g., the human users), thus a good evaluation protocol is probably to
evaluate the models' behaviors in comparison to the oracle. In this paper, we
introduce a new robustness measurement that directly measures the image
classification model's performance compared with a surrogate oracle (i.e., a
foundation model). Besides, we design a simple method that can accomplish the
evaluation beyond the scope of the benchmarks. Our method extends the image
datasets with new samples that are sufficiently perturbed to be distinct from
the ones in the original sets, but are still bounded within the same
image-label structure the original test image represents, constrained by a
foundation model pretrained with a large amount of samples. As a result, our
new method will offer us a new way to evaluate the models' robustness
performance, free of limitations of fixed benchmarks or constrained
perturbations, although scoped by the power of the oracle. In addition to the
evaluation results, we also leverage our generated data to understand the
behaviors of the model and our new evaluation strategies
Iterative Few-shot Semantic Segmentation from Image Label Text
Few-shot semantic segmentation aims to learn to segment unseen class objects
with the guidance of only a few support images. Most previous methods rely on
the pixel-level label of support images. In this paper, we focus on a more
challenging setting, in which only the image-level labels are available. We
propose a general framework to firstly generate coarse masks with the help of
the powerful vision-language model CLIP, and then iteratively and mutually
refine the mask predictions of support and query images. Extensive experiments
on PASCAL-5i and COCO-20i datasets demonstrate that our method not only
outperforms the state-of-the-art weakly supervised approaches by a significant
margin, but also achieves comparable or better results to recent supervised
methods. Moreover, our method owns an excellent generalization ability for the
images in the wild and uncommon classes. Code will be available at
https://github.com/Whileherham/IMR-HSNet.Comment: ijcai 202
BadLabel: A Robust Perspective on Evaluating and Enhancing Label-noise Learning
Label-noise learning (LNL) aims to increase the model's generalization given
training data with noisy labels. To facilitate practical LNL algorithms,
researchers have proposed different label noise types, ranging from
class-conditional to instance-dependent noises. In this paper, we introduce a
novel label noise type called BadLabel, which can significantly degrade the
performance of existing LNL algorithms by a large margin. BadLabel is crafted
based on the label-flipping attack against standard classification, where
specific samples are selected and their labels are flipped to other labels so
that the loss values of clean and noisy labels become indistinguishable. To
address the challenge posed by BadLabel, we further propose a robust LNL method
that perturbs the labels in an adversarial manner at each epoch to make the
loss values of clean and noisy labels again distinguishable. Once we select a
small set of (mostly) clean labeled data, we can apply the techniques of
semi-supervised learning to train the model accurately. Empirically, our
experimental results demonstrate that existing LNL algorithms are vulnerable to
the newly introduced BadLabel noise type, while our proposed robust LNL method
can effectively improve the generalization performance of the model under
various types of label noise. The new dataset of noisy labels and the source
codes of robust LNL algorithms are available at
https://github.com/zjfheart/BadLabels
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