There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Learning and then recognizing a route, whether travelled during the day or at night, in clear or inclement weather, and in summer or winter is a challenging task for state of the art algorithms in computer vision and robotics. In this paper, we present a new approach to visual navigation under changing conditions dubbed SeqSLAM. Instead of calculating the single location most likely given a current image, our approach calculates the best candidate matching location within every local navigation sequence. Localization is then achieved by recognizing coherent sequences of these “local best matches”. This approach removes the need for global matching performance by the vision front-end - instead it must only pick the best match within any short sequence of images. The approach is applicable over environment changes that render traditional feature-based techniques ineffective. Using two car-mounted camera datasets we demonstrate the effectiveness of the algorithm and compare it to one of the most successful feature-based SLAM algorithms, FAB-MAP. The perceptual change in the datasets is extreme; repeated traverses through environments during the day and then in the middle of the night, at times separated by months or years and in opposite seasons, and in clear weather and extremely heavy rain. While the feature-based method fails, the sequence-based algorithm is able to match trajectory segments at 100% precision with recall rates of up to 60%.

SeqSLAM : visual route-based navigation for sunny summer days and stormy winter nights

During the 1990s, numerous worldwide research and development activities have occurred in underwater robotics, especially in the area of autonomous underwater vehicles (AUVs). As the ocean attracts great attention on environmental issues and resources as well as scientific and military tasks, the need for and use of underwater robotic systems has become more apparent. Great efforts have been made in developing AUVs to overcome challenging scientific and engineering problems caused by the unstructured and hazardous ocean environment. In the 1990s, about 30 new AUVs have been built worldwide. With the development of new materials, advanced computing and sensory technology, as well as theoretical advancements, R&D activities in the AUV community have increased. However, this is just the beginning for more advanced, yet practical and reliable AUVs. This paper surveys some key areas in current state-of-the-art underwater robotic technologies. It is by no means a complete survey but provides key references for future development. The new millennium will bring advancements in technology that will enable the development of more practical, reliable AUVs.

Design and Control of Autonomous Underwater Robots: A Survey

Electro-rheological (ER) fluids are now regarded as one of the most versatile of the materials available for building smart structures and machines. In principle, ER fluids promise an elegant means of providing continuously variable forces for the control of mechanical vibrations. In practice, the development of industrial devices has been hampered by the unavailability of suitable ER fluids. Prompted by recent advances in ER fluid development this paper provides a comprehensive survey of ER devices for vibration control. The key modes of operation are identified and progress towards a unified approach to visualizing the macroscopic behaviour is summarized before presenting a comprehensive survey which includes contributions to the identification of ER fluid dynamics and the application of feedback control. The discussion of results includes some thoughts on future trends.

https://iopscience.iop.org/article/10.1088/0964-1726/5/4/011/pdf

Applications of electro-rheological fluids in vibration control: a survey

Tracking and formation control of multiple autonomous agents: A two-level consensus approach

This paper proposes a potential field-based method for high speed navigation of unmanned ground vehicles (UGVs) on uneven terrain. A potential field is generated in the two-dimensional “trajectory space” of the UGV path curvature and longitudinal velocity. Dynamic constraints, terrain conditions, and navigation conditions can be expressed in this space. A maneuver is chosen within a set of performance bounds, based on the potential field gradient. In contrast to traditional potential field methods, the proposed method is subject to local maximum problems, rather than local minimum. It is shown that a simple randomization technique can be employed to address this problem. Simulation and experimental results show that the proposed method can successfully navigate a UGV between pre-defined waypoints at high speed, while avoiding unknown hazards. Further, vehicle velocity and curvature are controlled to avoid rollover and excessive side slip. The method is computationally efficient, and thus suitable for on-board real-time implementation.

Potential Field Navigation of High Speed Unmanned Ground Vehicles on Uneven Terrain

This paper presents a novel concept of self-organizing collective robots with morphogenesis in a vertical plane. It is potentially applicable to autonomous mobile robots. For physical reconfiguration of a swarm of robots against gravity, new types of mechanisms and control strategies are proposed and demonstrated. Prototype robots have been fabricated in order to confirm the basic feasibility of the mechanisms. Each robot is composed of a body and a pair of arms. The body can be regarded as a cube with edge length of 90 mm, and is equipped with permanent magnets for bonding with another robot. The arms change the bonding configuration by rotating and sliding motions. As for the control strategies, we proposed the algorithms which can locally generate specific global formations of robots, with minimum interactions between neighboring robots. The overall scheme is similar to cellular automata. The control algorithms proposed have been tested by simulations.

Self-organizing collective robots with morphogenesis in a vertical plane

Unmanned ground vehicles have important applications in high speed rough terrain scenarios. In these scenarios, unexpected and dangerous situations can occur that require rapid hazard avoidance man ...

Hazard Avoidance for High-Speed Mobile Robots in Rough Terrain

This paper presents a novel concept of self-organizing collective robots with morphogenesis in a vertical plane.For physical reconfiguration of a swarm of robots against gravity, new types of mechanisms and control strategies are proposed and demonstrated.Basic feasibility of the mechanisms was confirmed through an experiment adopting four prototype robots.Each robot is composed of a body and a pair of arms.The body is equipped with permanent magnets for bonding with another robot.The arms change the bonding configuration by rotating and sliding motions.As for the control strategies, we proposed algorithms which can generate specific global formations of robots from local and minimum interactions between neighboring robots.It is shown that the proposed algorithms can successfully conduct the swarm of robots to the predetermined configurations.

/pdf/self-organizing-collective-robots-with-morphogenesis-in-a-287i98uljp.pdf

In this paper, a vision based autonomous underwater vehicle (AUV) navigation system is proposed and its performance is demonstrated by an autonomous underwater cable tracking (AUCT) mission at Lake Biwa using the test bed AUV "Twin-Burger" available at the University of Tokyo. The proposed system for the AUCT consist of three levels of controllers; namely, the higher level controller, the middle level controller and the lower level controller to navigate the AUV. A single CCD camera and an acoustic sensor are used to determine the relative position of the underwater cable with respect to the AUV in 3 dimensional space. Visual data provide two dimensions and acoustic data provide the third dimension. An image filtering technique to reduce some undesirable features which are unique to the underwater images, is used based on the Laplacian of the Gaussian (LoG) operator. A real-time algorithm is developed to determine the position of the cable in the image plane by cascading an estimator governed by AUV dynamics, with the Hough transformation technique. At the Lake Biwa mission, the proposed system performed very well other than in situations where the cable was covered by waterweeds for a long distance. The proposed system can be used as a solution to the problem of underwater positioning especially in pre-determined areas.

Yoji Kuroda

Papers

Potential Field Navigation of High Speed Unmanned Ground Vehicles on Uneven Terrain

Self-organizing collective robots with morphogenesis in a vertical plane

Hazard Avoidance for High-Speed Mobile Robots in Rough Terrain

Self-organizing collective robots with morphogenesis in a vertical plane

Vision based autonomous underwater vehicle navigation: underwater cable tracking