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A Debris Clearance Robot for Extreme Environments

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Abstract

The need for nuclear decommissioning is increasing globally, as power stations and other facilities utilising nuclear reaches the end of their operational life. Currently the majority of decommissioning tasks are carried out by workers in protective air fed suits, which is slow, expensive and dangerous. The work presented here is the early stages in the development of a flexible mobile manipulator platform, combining a Clearpath Husky, a Universal UR5 manipulator and various sensors. The system will be used for research specifically in the area of exploration of contaminated environments, map building to aid in task planning, and also to investigate manipulation for waste sorting. The aim is to develop a system that can, in the short term, be used in real world tasks but longer term function as a research platform to allow continued research and development. As well as developing a hardware platform, a detailed simulation model is also being developed to allow testing of algorithms in simulation before being deployed on hardware. The use of the simulation model for operator training is also an area that will be investigated in the future. This article focuses on the planned work for developing the system, as well as discussing the progress on the simulation model.

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... The nuclear industry is responsible for many legacy facilities that are in the process of being decommissioned. These facilities range from research and development laboratories built in the 1940s, to more recent plants, which have come to the end of their design life (Lee et al., 2020;West et al., 2019;Zhang et al., 2020). Nuclear decommissioning is an expensive and time consuming process, mainly due to the hazardous nature of the work (Sato et al., 2019), which is compounded by uncertainties in the nuclear materials that may be present and the integrity and layout of facilities (Bandala et al., 2019). ...
... Power was provided to the robot via a tether system that used a bank of lead acid batteries to save mass and increase ease of transportation, when compared to the petrol generator system the robot was initially designed to use. West et al. (2019), proposed a tether management system to prevent their tether from tangling in the robot's drive mechanism and snagging in the environment, which was stated to be a significant risk in their work, and could potentially cause the robot to become stuck and have to be abandoned. ...
... Whilst consideration was taken in some cases to ensure that the robots could be decontaminated (wheels/ tracks removed and disposed of, chassis washed with detergent and pressure washer Guzman et al., 2016;Kawatsuma et al., 2017), this still required operators to physically clean the robot, which introduces risk, and this necessity had to be taken into account during the design phase (such as ensuring the robot was water tight). All of the reviewed works featured some kind of robotic manipulator, however, in the specific applications that were being addressed there was no evidence presented that showed a requirement that the payload needed to be 5 kg or more (with the exception of West et al's work; West et al., 2019), with many tasks in radioactive environments, such as gathering small samples or taking surface swab samples for later chemical analysis, typically possible with a much lower payload capacity. ...
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This paper presents the Vega robot, which is a small, low cost, potentially disposable ground robot designed for nuclear decommissioning. Vega has been developed specifically to support characterization and inspection operations, such as 2D and 3D mapping, radiation scans and sample retrieval. The design and construction methodology that was followed to develop the robot is described and its capabilities detailed. Vega was designed to provide flexibility, both in software and hardware, is controlled via tele-operation, although it can be extended to semi and full autonomy, and can be used in either tethered or untethered configurations. A version of the tethered robot was designed for extreme radiation tolerance, utilizing relay electronics and removing active electronic systems. Vega can be outfitted with a multitude of sensors and actuators, including gamma spectrometers, alpha/beta radiation sensors, LiDARs and robotic arms. To demonstrate its flexibility, a 5 degree-of-freedom manipulator has been successfully integrated onto Vega, facilitating deployments where handling is required. To assess the tolerance of Vega to the levels of ionizing radiation that may be found in decommissioning environments, its individual components were irradiated, allowing estimates to be made of the length of time Vega would be able to continue to operate in nuclear environments. Vega has been successfully deployed in an active environment at the Dounreay nuclear site in the UK, deployed in nonactive environments at the Atomic Weapons Establishment, and demonstrated to many other organizations in the UK nuclear industry including Sellafield Ltd, with the goal of moving to active deployments in the future.
... Limited by this, the options for mobile robots are to either return to a base station for charging, have its battery replaced manually, or operate with a tether. The first two options result in downtime for the robot while the third option presents additional challenges such as tether crossovers, limited bending around obstacles, reduce in the robot payload from the tether system, all of which limit the mobility and performance of the robot [8]. ...
... Both wheel and legged robots of medium (ANYmal and Husky) and small (Jackal and Corin) scale have been included for ground-based robots as these platforms have gained significant interest in the industry and research community due to their availability or capability that previous platforms have not been capable of achieving [8,14,15]. The AVEXIS and BlueROV represent the mini-and small autonomous underwater vehicle (AUV) scale robot which is more suitable for the hazardous environment [16]. ...
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Advances in technology have seen mobile robots becoming a viable solution to many global challenges. A key limitation for tetherless operation, however, is the energy density of batteries. Whilst significant research is being undertaken into new battery technologies, wireless power transfer may be an alternative solution. The majority of the available technologies are not targeted toward the medium power requirements of mobile robots; they are either for low powers (a few Watts) or very large powers (kW). This paper reviews existing wireless power transfer technologies and their applications on mobile robots. The challenges of using these technologies on mobile robots include delivering the power required, system efficiency, human safety, transmission medium, and distance, all of which are analyzed for robots operating in a hazardous environment. The limitations of current wireless power technologies to meet the challenges for mobile robots are discussed and scenarios which current wireless power technologies can be used on mobile robots are presented.
... More recently, the emergence and growth of care robotics, advancements in prosthetics limbs and associated research [2,3] renewed attention on this topic due to the need for closing the distance between platforms and users. New materials and advancements in tactile systems contributed to the flourishing of new studies, areas of interests, and applications, for example, the rising need for robots to take over complex and risky [4,5] tasks in hazardous environments to safeguard human lives. Tasks in radioactive or corrosive environments require spatial awareness and sensory feedback to be performed effectively. ...
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This work introduces an array prototype based on a Frequency Modulation (FM) encoding architecture to transfer multiple sensor signals on a single wire. The use case presented adopts Hall-effect sensors as an example to represent a much larger range of sensor types (e.g., proximity and temperature). This work aims to contribute to large area artificial skin systems which are a key element to enhance robotic platforms. Artificial skin will allow robotic platforms to have spatial awareness which will make interaction with objects and users safe. The FM-based architecture has been developed to address limitations in large-scale artificial skin scalability. Scalability issues include power requirements; number of wires needed; as well as frequency, density, and sensitivity bottlenecks. In this work, eight sensor signals are simultaneously acquired, transferred on a single wire and decoded in real-time. The overall taxel array current consumption is 36 mA. The work experimentally validates and demonstrates that different input signals can be effectively transferred using this approach minimizing wiring and power consumption of the taxel array. Four different tests using single as well as multiple stimuli are presented. Observations on performances, noise, and taxel array behaviour are reported. The results show that the taxel array is reliable and effective in detecting the applied stimuli.
... Previous use of physics simulators and video game engines to recreate nuclear environments has largely been separated into two sub categories. There have been efforts to model radiation fields, predominantly for dosimetry training [43] and dose estimation of radiation workers, or to model robot deployment into mock nuclear facilities [44,45]. The former contains inverse square distance estimations of radiation exposure rate but not robot interaction, whereas the latter has simulated robot systems without radiation field estimations. ...
Article
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The utilisation of robots in hazardous nuclear environments has potential to reduce risk to humans. However, historical use has been largely limited to specific missions rather than broader industry-wide adoption. Testing and verification of robotics in realistic scenarios is key to gaining stakeholder confidence but hindered by limited access to facilities that contain radioactive materials. Simulations offer an alternative to testing with actual radioactive sources, provided they can readily describe the behaviour of robotic systems and ionising radiation within the same environment. This work presents a quick and easy way to generate simulated but realistic deployment scenarios and environments which include ionising radiation, developed to work within the popular robot operating system compatible Gazebo physics simulator. Generated environments can be evolved over time, randomly or user-defined, to simulate the effects of degradation, corrosion or to alter features of certain objects. Interaction of gamma radiation sources within the environment, as well as the response of simulated detectors attached to mobile robots, is verified against the MCNP6 Monte Carlo radiation transport code. The benefits these tools provide are highlighted by inclusion of three real-world nuclear sector environments, providing the robotics community with opportunities to assess the capabilities of robotic systems and autonomous functionalities.
... Currently, research and development in robotics and its applications is an actively growing field, including the development of robotics applications in assisting first responders in rescue missions, in which the main objective is to improve the search and rescue (SAR) operation to become faster and safer. A wide range of robotics design has been introduced and deployed for specifically performing SAR missions [4][5][6][7][8][9][10][11]. Most of these robots are designed to assist with some specific tasks that can be grouped into four general categories according to their purpose in the SAR response process, namely search, extraction, evacuation, and treatment [5]. ...
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... 1 A mobile manipulator is composed of a robotic manipulator mounted on a mobile base, offering both mobility and dexterity. Many different professional and consumer service applications have been envisioned for mobile manipulators, mainly to perform manufacturing assistance in industrial environments [4,5], to execute domestic service tasks [3,6] and human assistance [7,8], to transport goods inside warehouses and stores [9,10] and to manipulate and transport objects in hazardous environments such as in search and rescue missions [11,12] or in areas with radioactive or toxic debris [13]. There has been a growing interest in the research community in developing autonomous mobile manipulators, ranging from wheeled-mobile robots [14,15] to humanoids [16], legged robots [17] and even aerial robots [18]. ...
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Robots compete in nuclear decommissioning challenge
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