Biomechanics Group Institute of Biomedical Engineering University of Oxford ------------------------------------- Center for Neuroinformatics BioX Laboratory Zhejiang University
liyu.wang@wadh.oxon.org
A life traveler with amazing human locomotion A passionate soul to search its location in the brain A fresh wind to chase truth and freedom A Chinese revolutionist in technology
Abstract: Despite many approaches proposed in the past, robotic climbing in a complex vertical environment is still a big challenge. We present here an alternative climbing technology that is based on thermoplastic adhesive (TPA) bonds. The approach has a great advantage because of its large payload capacity and viability to a wide range of flat surfaces and complex vertical terrains. The large payload capacity comes from a physical process of thermal bonding, while the wide applicability benefits from rheological properties of TPAs at higher temperatures and intermolecular forces between TPAs and adherends when being cooled down. A particular type of TPA has been used in combination with two robotic platforms, featuring different foot designs, including heating/cooling methods and construction of footpads. Various experiments have been conducted to quantitatively assess different aspects of the approach. Results show that an exceptionally high ratio of 500% between dynamic payloads and body mass can be achieved for stable and repeatable vertical climbing on flat surfaces at a low speed. Assessments on four types of typical complex vertical terrains with a measure, i.e., terrain shape index ranging from -0.114 to 0.167, return a universal success rate of 80%--100%.
Abstract: Physical connection and disconnection control has practical meanings for robot applications. Compared to conventional connection mechanisms, bonding involving a thermal process could provide high connection strength, high repeatability, and power-free connection maintenance, etc. In terms of disconnection, an established bond can be easily weakened with a temperature rise of the material used to form the bond. Hot melt adhesives (HMAs) are such material that can form adhesive bonds with any solid surfaces through a thermally induced solidification process. This paper proposes a novel control method for automatic connection and disconnection based on HMAs. More specifically, mathematical models are first established to describe the flowing behavior of HMAs at higher temperatures, as well as the temperature-dependent strength of an established HMA bond. These models are then validated with a specific type of HMA in a minimalistic robot setup equipped with two mechatronic devices for automated material handling. The validated models are eventually used for determining open parameters in a feedback controller for the robot to perform a pick-and-place task. Through a series of trials with different wooden and aluminum parts, we evaluate the performance of the automatic connection and disconnection methods in terms of speed, energy consumption, and robustness.
Abstract: I attended the CCTV 'Pigeon' media writing competition for school students in 1996, and wrote a story of a touching interaction between two students who had a big argument before. The story was selected into the book published in 1998.
Abstract: Vertical climbing on a variety of flat surfaces with a single robot has been previously demonstrated using vacuum suction, electrostatic adhesion, and biologically inspired approaches, etc. These methods generally have a low attachment strength, and it is not clear whether they can provide satisfactory attachment on vertical terrains with richer 3D features. Recent development of a climbing technology based on hot melt adhesives (HMAs) has shown its advantage with a high attachment strength through thermal bonding and viability to any solid surfaces. However, its feasibility for vertical climbing has only been proven on flat surfaces and with external energy supplies. This paper provides quantitative measurements for vertical climbing performance on five types of surfaces and terrains with a self-contained robot exploiting HMAs. We show that robust vertical climbing on multiple terrains can be achieved with reliable high-strength attachment.
Abstract: Modular self-reconfigurable robots have previously demonstrated that automatic control of their own body shapes enriches their behavioural functions. However, having predefined rigid modules technically limits real-world systems from being hyper-redundant and compliant. Encouraged by recent progress using elastically deformable material for robots, we propose the concept of âsoft self-reconfigurable robotsâ which may become hyper-flexible during interaction with the environment. As the first attempt towards this goal, the paper proposes a novel approach using viscoelastic material Hot-Melt Adhesives (HMAs): for physical connection and disconnection control between bodies that are not necessarily predefined rigid modules. We present a model that characterizes the temperature dependency of the strength of HMA bonds, which is then validated and used in a feedback controller for automatic connection and disconnection. Using a minimalistic robot platform that is equipped with two devices handling HMAs, the performance of this method is evaluated in a pick-and-place experiment with aluminium and wooden parts.
Abstract: The capability of extending body structures is one of the most significant challenges in the robotics research and it has been partially explored in self-reconfigurable robotics. By using such a capability, a robot is able to adaptively change its structure from, for example, a wheel like body shape to a legged one to deal with complexity in the environment. Despite their expectations, the existing mechanisms for extending body structures are still highly complex and the flexibility in self-reconfiguration is still very limited. In order to account for the problems, this paper investigates a novel approach to robotic body extension by employing an unconventional material called Hot Melt Adhesives (HMAs). Because of its thermo-plastic and thermo-adhesive characteristics, this material can be used for additive fabrication based on a simple robotic manipulator while the established structures can be integrated into the robot's own body to accomplish a task which could not have been achieved otherwise. This paper first investigates the HMA material properties and its handling techniques, then evaluates performances of the proposed robotic body extension approach through a case study of a âwater scoopingâ task.
Abstract: Robust climbing in unstructured environments is a long-standing challenge in robotics research. Recently there has been an increasing interest in using adhesive materials for that purpose. For example, a climbing robot using hot melt adhesives (HMAs) has demonstrated advantages in high attachment strength, reasonable operation costs, and applicability to different surfaces. Despite the advantages, there still remain several problems related to the attachment and detachment operations, which prevent this approach from being used in a broader range of applications. Among others, one of the main problems lies in the fact that the adhesive characteristics of this material were not fully understood fin the context of robotic climbing locomotion. As a result, the previous robot often could not achieve expected locomotion performances and âcontaminatedâ the environment with HMAs left behind. In order to improve the locomotion performances, this paper focuses on attachment and detachment operations in robot climbing with HMAs. By systematically analyzing the adhesive property and bonding strength of HMAs to different materials, we propose a novel detachment mechanism that substantially improves climbing performances without HMA traces.
Abstract: Based on the research on mechanism of biological olfactory system, we constructed a K-set, which is a novel bionic neural network. Founded on the groundwork of K0, KI and KII sets, the KIII set in the K-set hierarchy simulates the whole olfactory neural system. In contrast to the conventional artificial neural networks, the KIII set operates in nonconvergent 'chaotic' dynamical modes similar to the biological olfactory system. In this paper, an application of electronic nose-brain for tea classification using the KIII set is presented and its performance is evaluated in comparison with other methods.
Notes: primary exploration to human visual neural network
Abstract: Ever since the word 'ROBOT' first appeared in a science fiction in 1921, scientists and engineers have been trying different ways to create it. Present technologies in mechanical and electrical engineering makes it possible to have robots in such places as industrial manufacturing and assembling lines. Although they are essentially robotic arms or similarly driven by electrical power and signal control, they could be treated the primitive pioneers in application. Researches in the laboratories go much further. Interdisciplines are directing the evolution of more advanced robots. Among these are artificial intelligence, computational neuroscience, mathematics and robotics. These disciplines come closer as more complex problems emerge.
From a robot's point of view, three basic abilities are needed. They are thinking and memory, sensory perceptions, control and behaving. These are capabilities we human beings have to adapt ourselves to the environment. Although researches on robots, especially on intelligent thinking, progress slowly, a revolution for biological inspired robotics is spreading out in the laboratories all over the world.
Notes: Tea Classification Based on Artificial Olfaction Using Bionic Olfactory Neural Network,
Biomechanics research
Abstract: The project was initiated by the Civil Engineering Group in the Department of Engineering Science. It addresses the problem of how the forces between the feet and the ground (ground forces) are related to human upper body movement during jumping and bobbing. There was a lack of information about whether we could estimate the forces placed on a structure such as a grandstand by tracking movements of the people who walked, jumped, or bobbed on the structure. To this end, experimental work was performed in the Oxford Gait Laboratory.
The testing part of the project involved volunteers jumping and bobbing in the gait lab. Infrared reflective markers were attached to major bony landmarks on the subject's body. The subjects jumped or bobbed to the beep of a metronome set at frequencies between 90 and 180 beats per minute. The movement of the subjects was recorded by means of 12 infrared cameras as part of Vicon motion capture system. The ground reaction force induced by each subject will be measured by force plates.
The result provides important data which be of direct interest to both structural engineers and safety system designers. Ultimately, the project will benefit the safety of the many people who attend sports and music events in modern stadia. The work will also make an important contribution to the wider body of knowledge on human body movement and human-structure interaction, as well as bionic design for humanoid robots.
Abstract: Aus diesem Grund hat sich auch der Chinese Wang Liyu für einen Anfängerkurs angemeldet: «Im akademischen Umfeld sprechen zwar fast alle Englisch», sagt der 26-Jährige, der an der ETH im Bereich Robotik und intelligente Systeme doktoriert. Um den Alltag in Zürich zu meistern, sei sein Kurs aber sehr hilfreich gewesen. «Wie frage ich nach der Zeit oder dem Weg? Wie miete ich ein Zimmer? Am Sprachenzentrum werden solche Fragen sehr praxisorientiert behandelt», berichtet Wang.
Notes: Invited comment in a news report on a social problem caused by individual's occupation of public squares in the city of Guangzhou, where I compared the operation systems for individual's use of public places in China and the UK.
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