831 research outputs found
SOTER: A Runtime Assurance Framework for Programming Safe Robotics Systems
The recent drive towards achieving greater autonomy and intelligence in
robotics has led to high levels of complexity. Autonomous robots increasingly
depend on third party off-the-shelf components and complex machine-learning
techniques. This trend makes it challenging to provide strong design-time
certification of correct operation.
To address these challenges, we present SOTER, a robotics programming
framework with two key components: (1) a programming language for implementing
and testing high-level reactive robotics software and (2) an integrated runtime
assurance (RTA) system that helps enable the use of uncertified components,
while still providing safety guarantees. SOTER provides language primitives to
declaratively construct a RTA module consisting of an advanced,
high-performance controller (uncertified), a safe, lower-performance controller
(certified), and the desired safety specification. The framework provides a
formal guarantee that a well-formed RTA module always satisfies the safety
specification, without completely sacrificing performance by using higher
performance uncertified components whenever safe. SOTER allows the complex
robotics software stack to be constructed as a composition of RTA modules,
where each uncertified component is protected using a RTA module.
To demonstrate the efficacy of our framework, we consider a real-world
case-study of building a safe drone surveillance system. Our experiments both
in simulation and on actual drones show that the SOTER-enabled RTA ensures the
safety of the system, including when untrusted third-party components have bugs
or deviate from the desired behavior
Autonomous Task Planning for Heterogeneous Multi-Agent Systems
This paper presents a solution to the automatic task planning problem for
multi-agent systems. A formal framework is developed based on the
Nondeterministic Finite Automata with -transitions, where given the
capabilities, constraints and failure modes of the agents involved, an initial
state of the system and a task specification, an optimal solution is generated
that satisfies the system constraints and the task specification. The resulting
solution is guaranteed to be complete and optimal; moreover a heuristic
solution that offers significant reduction of the computational requirements
while relaxing the completeness and optimality requirements is proposed. The
constructed system model is independent from the initial condition and the task
specification, alleviating the need to repeat the costly pre-processing cycle
for solving other scenarios, while allowing the incorporation of failure modes
on-the-fly. Two case studies are provided: a simple one to showcase the
concepts of the proposed methodology and a more elaborate one to demonstrate
the effectiveness and validity of the methodology.Comment: Long version of paper submitted to the IEEE ICRA 2023 Conferenc
Hot-swapping robot task goals in reactive formal synthesis
We consider the problem of synthesizing robot controllers to realize a task that unpredictably changes with time. Tasks are formally expressed in the GR(1) fragment of temporal logic, in which some of the variables are set by an
adversary. The task changes by the addition or removal of goals, which occurs online (i.e., at run-time). We present an algorithm for mending control
strategies to realize tasks after the addition of goals, while avoiding global
re-synthesis of the strategy. Experiments are presented for a planar
surveillance task in which new regions of interest are incrementally added.
Run-times are empirically shown to be favorable compared to re-synthesizing from scratch. We also present an algorithm for mending control strategies for the removal of goals. While in this setting the original strategy is still
feasible, our algorithm provides a more satisfying solution by "tightening
loose ends.'' Both algorithms are shown to yield so-called reach annotations,
and thus the control strategies are easily amenable to other algorithms
concerning incremental synthesis, e.g., as in previous work by the authors for
navigation in uncertain environments
Formalization of Robot Collision Detection Method based on Conformal Geometric Algebra
Cooperative robots can significantly assist people in their productive
activities, improving the quality of their works. Collision detection is vital
to ensure the safe and stable operation of cooperative robots in productive
activities. As an advanced geometric language, conformal geometric algebra can
simplify the construction of the robot collision model and the calculation of
collision distance. Compared with the formal method based on conformal
geometric algebra, the traditional method may have some defects which are
difficult to find in the modelling and calculation. We use the formal method
based on conformal geometric algebra to study the collision detection problem
of cooperative robots. This paper builds formal models of geometric primitives
and the robot body based on the conformal geometric algebra library in HOL
Light. We analyse the shortest distance between geometric primitives and prove
their collision determination conditions. Based on the above contents, we
construct a formal verification framework for the robot collision detection
method. By the end of this paper, we apply the proposed framework to collision
detection between two single-arm industrial cooperative robots. The flexibility
and reliability of the proposed framework are verified by constructing a
general collision model and a special collision model for two single-arm
industrial cooperative robots
Advanced flight control system study
A fly by wire flight control system architecture designed for high reliability includes spare sensor and computer elements to permit safe dispatch with failed elements, thereby reducing unscheduled maintenance. A methodology capable of demonstrating that the architecture does achieve the predicted performance characteristics consists of a hierarchy of activities ranging from analytical calculations of system reliability and formal methods of software verification to iron bird testing followed by flight evaluation. Interfacing this architecture to the Lockheed S-3A aircraft for flight test is discussed. This testbed vehicle can be expanded to support flight experiments in advanced aerodynamics, electromechanical actuators, secondary power systems, flight management, new displays, and air traffic control concepts
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