14 research outputs found
Enhancing State Estimator for Autonomous Race Car : Leveraging Multi-modal System and Managing Computing Resources
This paper introduces an innovative approach to enhance the state estimator
for high-speed autonomous race cars, addressing challenges related to
unreliable measurements, localization failures, and computing resource
management. The proposed robust localization system utilizes a Bayesian-based
probabilistic approach to evaluate multimodal measurements, ensuring the use of
credible data for accurate and reliable localization, even in harsh racing
conditions. To tackle potential localization failures during intense racing, we
present a resilient navigation system. This system enables the race car to
continue track-following by leveraging direct perception information in
planning and execution, ensuring continuous performance despite localization
disruptions. Efficient computing resource management is critical to avoid
overload and system failure. We optimize computing resources using an efficient
LiDAR-based state estimation method. Leveraging CUDA programming and GPU
acceleration, we perform nearest points search and covariance computation
efficiently, overcoming CPU bottlenecks. Real-world and simulation tests
validate the system's performance and resilience. The proposed approach
successfully recovers from failures, effectively preventing accidents and
ensuring race car safety.Comment: arXiv admin note: text overlap with arXiv:2207.1223
Design, Field Evaluation, and Traffic Analysis of a Competitive Autonomous Driving Model in a Congested Environment
Recently, numerous studies have investigated cooperative traffic systems
using the communication among vehicle-to-everything (V2X). Unfortunately, when
multiple autonomous vehicles are deployed while exposed to communication
failure, there might be a conflict of ideal conditions between various
autonomous vehicles leading to adversarial situation on the roads. In South
Korea, virtual and real-world urban autonomous multi-vehicle races were held in
March and November of 2021, respectively. During the competition, multiple
vehicles were involved simultaneously, which required maneuvers such as
overtaking low-speed vehicles, negotiating intersections, and obeying traffic
laws. In this study, we introduce a fully autonomous driving software stack to
deploy a competitive driving model, which enabled us to win the urban
autonomous multi-vehicle races. We evaluate module-based systems such as
navigation, perception, and planning in real and virtual environments.
Additionally, an analysis of traffic is performed after collecting multiple
vehicle position data over communication to gain additional insight into a
multi-agent autonomous driving scenario. Finally, we propose a method for
analyzing traffic in order to compare the spatial distribution of multiple
autonomous vehicles. We study the similarity distribution between each team's
driving log data to determine the impact of competitive autonomous driving on
the traffic environment
A Versatile Door Opening System with Mobile Manipulator through Adaptive Position-Force Control and Reinforcement Learning
The ability of robots to navigate through doors is crucial for their
effective operation in indoor environments. Consequently, extensive research
has been conducted to develop robots capable of opening specific doors.
However, the diverse combinations of door handles and opening directions
necessitate a more versatile door opening system for robots to successfully
operate in real-world environments. In this paper, we propose a mobile
manipulator system that can autonomously open various doors without prior
knowledge. By using convolutional neural networks, point cloud extraction
techniques, and external force measurements during exploratory motion, we
obtained information regarding handle types, poses, and door characteristics.
Through two different approaches, adaptive position-force control and deep
reinforcement learning, we successfully opened doors without precise trajectory
or excessive external force. The adaptive position-force control method
involves moving the end-effector in the direction of the door opening while
responding compliantly to external forces, ensuring safety and manipulator
workspace. Meanwhile, the deep reinforcement learning policy minimizes applied
forces and eliminates unnecessary movements, enabling stable operation across
doors with different poses and widths. The RL-based approach outperforms the
adaptive position-force control method in terms of compensating for external
forces, ensuring smooth motion, and achieving efficient speed. It reduces the
maximum force required by 3.27 times and improves motion smoothness by 1.82
times. However, the non-learning-based adaptive position-force control method
demonstrates more versatility in opening a wider range of doors, encompassing
revolute doors with four distinct opening directions and varying widths
Investigation of wound healing process guided by nano-scale topographic patterns integrated within a microfluidic system
<div><p>When living tissues are injured, they undergo a sequential process of homeostasis, inflammation, proliferation and maturation, which is called wound healing. The working mechanism of wound healing has not been wholly understood due to its complex environments with various mechanical and chemical factors. In this study, we propose a novel <i>in vitro</i> wound healing model using a microfluidic system that can manipulate the topography of the wound bed. The topography of the extracellular matrix (ECM) in the wound bed is one of the most important mechanical properties for rapid and effective wound healing. We focused our work on the topographical factor which is one of crucial mechanical cues in wound healing process by using various nano-patterns on the cell attachment surface. First, we analyzed the cell morphology and dynamic cellular behaviors of NIH-3T3 fibroblasts on the nano-patterned surface. Their morphology and dynamic behaviors were investigated for relevance with regard to the recovery function. Second, we developed a highly reproducible and inexpensive research platform for wound formation and the wound healing process by combining the nano-patterned surface and a microfluidic channel. The effect of topography on wound recovery performance was analyzed. This <i>in vitro</i> wound healing research platform will provide well-controlled topographic cue of wound bed and contribute to the study on the fundamental mechanism of wound healing.</p></div
Nano-pattern integrated microfluidic system used to reproduce the wound healing process.
<p><b>(A)</b> CAD design of the microfluidic device, which includes 2 inlets, 1 outlet and a cell culture region. <b>(B)</b> Process used to fabricate the microfluidic channel and nano-pattern. The device and nano-patterns were irreversibly combined through plasma bonding methods. <b>(C)</b> 3D image of the combined microfluidic device with the nano-pattern. Schematic of the <i>in vitro</i> wound formation process in the microfluidic channel using the layered flow of trypsin/EDTA. Due to trypsinization, cells detached from the microfluidic channel, allowing the selective formation of a cell-free area.</p