Unmanned vehicles are popular for autonomous operation, especially in hazardous environments. Unfortunately, robot deployment in such environments can be challenging. Vehicles can be difficult to deploy and upon mission completion may require decontamination. A key issue in terms of remediation is that penetration of the vehicle body itself by the drive mechanism and sensors provides potential risks for environmental contaminants to enter into the vehicle. Sealing shafts, sensors and the like from external environment contamination can be difficult for many “off the shelf” autonomous robots. One vehicle design that avoids many of the issues associated with environmental contamination is the spherical robot design, such as the DragonBall. Spherical robots provide a number of advantages over their wheeled counterparts, but they also present a number of challenges and complexities. Chief among these are issues related to locomotive strategies and sensor placement and processing given the rolling nature of the device. Research on DragonBall helps to validate and test applications of spherical robots in hazardous environments. Some challenges include: placement of the sensor of the DragonBall, designing a control system, and construction.
Paper: The paper was published in RoManSy 2020, Japan, Tokyo: Robot Design, Dynamics and Control pp 305-312. View the paper here.
Dome Manufacturing"Research robots are often built to test the viability of such platforms to perform certain tasks. Quite often such research platforms are designed only to work within the lab or in an indoor environment. DragonBall however, was built to validate the design of a spherical robot platform for both indoor and outdoor experiments. Unlike a typical indoor robot it is important for an outdoor robot to be robust to a wide range of conditions. This introduces further design challenges. Mobile robots operating in an outdoor experiment can be easily damaged due to mishandling, bad weather, rough terrain, etc. As discussed previously, the shortcomings of acrylic dome design made it necessary to search for materials with lightweight and good stiffness. Composite building materials have become very popular due to their availability for com-mercial applications. Fiberglass and carbon fiber are perhaps the most popular composite materials. For this project carbon fiber was chosen over fiberglass as it provides more stiff-ness than fiberglass. This choice offers increased strength and better scratch resistance while maintaining lower weight over fiberglass. Although the DragonBall robot is light in weight,having a strong body ensures that if operations such as falling from a height are required,the robot will be able to do so. The operation of this robot will be not only limited to land, it should be able to navigate the surface of bodies of water as well. If the design is watertight, travelling over water should even be possible! Modifying this robot for operation in contaminated environments will also be straightforward as the robot has no penetration of the shell."