Practical Field Robotics
Practical Field Robotics
Overview of Field Robotics
Practical Field Robotics comprises the design and fabrication of machines that do useful work on their own, for the most part. Field Robotics separates us from robotics done in a protected laboratory environment. It is also somewhat removed from theoretical robotics that underpins much of what we do, but may not employ in the realization of machines. Laboratory machines may walk like a human 1 , or simply perform useful tasks that humans do in other ways.
When asked to describe a "robotic dishwasher," new students often elaborate on a machine that picks up one dish at a time and does the washing the same way a human would. This approach ignores the success of pumping scalding water around in a sealed box. The former approach expresses limitations that were never imposed by the question.
The robotics literature abounds with examples that expressly imitate how humans are built, rather than what they aim to do. Since our hands and eyes evolved to allow us to swing from trees and pick fruit, they may not afford the best characteristics needed for a more modern task 2 . We should not be tempted to imitate and then automate things we ought not do in the first place. For example, Elias Howe has been quoted as saying that he was inspired by watching his wife sewing in his work to invent the sewing machine 3 . Analysis of how people sew and how his machine sews shows that this could not be the case. Our methodology will steer us away from these pitfalls.
A successful design should always consider such constraints as artificial and aim for the function to be performed 4 . We will see ( Figure 1.1 ) an expression of high-level functions that not only informed the development of our case studies, but also suggested the layout of the chapters in this book.
Figure 1.1 The beginning of the FBD for a practical field robot for nuclear service
We will explore three examples of systematically designed field robotic systems, each illustrating key points of the design procedure and important lessons learned in the field. The first example is a mobile robot system, actually a pair of cooperating robots, used for field repair work in the commercial nuclear power plant area. This system was developed over time by several design teams considering the functions to be performed, and we will illustrate them here. Details of the system design remain proprietary but we can address the higher-level decision-making processes by reference to a patent issued to the author 5 . We will see that fully automatic control was not employed, but rather the concept of teleoperation , in which there are personnel in-the-loop at all times 6 , 7 . Special-purpose equipment and tooling were employed to create a level of autonomy for some subsystem tasks.
The second example involves the design and operation of the largest autonomous mobile robot ever built, to our knowledge. Its mission is to haul coal from an underground mine. Its field versions weigh hundreds of tons and span lengths of 160 m from end to end. Briefly, it comprises a continuous miner at the head end, a number of linked conveyors, and telescoping tail piece. While one terminal end does need a human driver, the balance of the system is autonomously driven through the mine, needing only periodic observation of its segments to ensure that no personnel come within its vicinity.
Finally, we present a detailed account of the design process and the operation of a low-budget mobile robot for automatically mowing a lawn at an affordable cost. To our knowledge this has not successfully been done until now. We initially examined six approaches to this problem, and each will be discussed before delving into the details of the selected concept.