High-integrity navigation: a frequency-domain approach

Abstract

This paper seeks to provide an autonomous navigation systems engineer with the tools and insights needed to design a high-integrity navigation system. The term "high integrity" is used here to describe a system that is robust to failure and at the very least can be guaranteed upon failure to attain a "safe" state. By designing for high integrity, the designer is acknowledging the fact that at some point in time, the system will fail. The time between failures may be maximized by choosing high-reliability components, but nevertheless the components (whether they be sensors, actuators, mechanics, computers, or even mathematical models) will at some time fail in potentially unpredictable ways. A navigation system is said to have high integrity if a guarantee is provided that while individual components may fail, the system as a whole will never fail in a catastrophic manner, and therefore will not require any human intervention. Without the guarantee of integrity, autonomous navigation systems will be difficult, if not impossible, to deploy in real-world applications. This paper aims to provide this guarantee by determining the necessary conditions that are required for a navigation system to be considered of high integrity. Frequency-domain techniques are used to model the contribution of sensor and process faults to navigation system performance. This methodology provides the foundation needed to design navigation systems with enough frequency redundant information to make possible reliable fault detection and identification over the entire operating frequency spectrum.

Optimization of the simultaneous localization and map-building algorithm for real-time implementation

“…These algorithms require the mobile robot to always be localized within certain bounds, meaning that it is not possible to address the initialisation or the "kidnapped robot" problem. This is not an issue for many industrial applications, [14,15,16], where large machines weighing many tonnes operate autonomously. In fact, in these applications the navigation system has to be designed with enough integrity in order to avoid, or at least recognize such faults and provide for appropriate safety procedures, [1].…”

Building a robust integrity monitoring algorithm for a low cost GPS-aided-INS system

“…Given a confidence level (percentage probability) of detection and the number of degrees of freedoms, the value of γ is determined from the 2 χ probability distribution tables prior to the fusion process and represents the probability that a particular observation lies within an ellipsoid [20]. Therefore, given a hypothesis 1 H of a fault being detected, and considering a probability of false detection of 5% (that is a 95% level of confidence), then…”

“…Therefore, there is an increasing interest in the area of reliability, integrity and fault tolerance. Reliability is component dependent, i.e., a navigation system is only reliable as its most unreliable component [1]. The probability that a component will fail is related to its rate of failure [2], and its reliability is measured by its mean time to failure (MTTF).…”

Field and service applications - An autonomous straddle carrier for movement of shipping containers - From Research to Operational Autonomous Systems

“…In this manner, the integrity of an integrated navigation system can be guaranteed to be correct; even if the output is "no valid position information." Such systems are referred to as high integrity rather than high reliability as the possibility of failure is made explicit in the design [7], [9].…”

“…It is critical that the position estimates for the vehicle are never wrong as this would result in catastrophic failure. Work on developing navigation systems with provable levels of integrity [9], [10] has been essential in this and other projects [8]. ◆ how to control a large vehicle operating on pneumatic tires at high-speed with large load changes.…”