Indoor UAV Localization Using a Tether

2017 IEEE International Symposium on Safety, Security and Rescue Robotics (SSRR)

2017

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This paper develops an autonomous tethered aerial visual assistant for robot operations in unstructured or confined environments. Robotic tele-operation in remote environments is difficult due to lack of sufficient situational awareness, mostly caused by the stationary and limited field-of-view and lack of depth perception from the robot's onboard camera. The emerging state of the practice is to use two robots, a primary and a secondary that acts as a visual assistant to overcome the perceptual limitations of the onboard sensors by providing an external viewpoint. However, problems exist when using a tele-operated visual assistant: extra manpower, manually chosen suboptimal viewpoint, and extra teamwork demand between primary and secondary operators. In this work, we use an autonomous tethered aerial visual assistant to replace the secondary robot and operator, reducing human robot ratio from 2:2 to 1:2. This visual assistant is able to autonomously navigate through unstructured or confined spaces in a risk-aware manner, while continuously maintaining good viewpoint quality to increase the primary operator's situational awareness. With the proposed co-robots team, tele-operation missions in nuclear operations, bomb squad, disaster robots, and other domains with novel tasks or highly occluded environments could benefit from reduced manpower and teamwork demand, along with improved visual assistance quality based on trustworthy risk-aware motion in cluttered environments.

Section: Tether-based Indoor Localizationmentioning

confidence: 99%

“…On the other (a) Localization Model (b) FBD of UAV (c) FBD ofTether Fig. 5 Tether-based Localization [17] hand, velocity control based on the system's inverse Jacobian matrix computes velocity commands L , θ , and φ using an instantaneous velocity vector pointing from current location to next waypoint d − → x /dt (Eqn. 2).…”

Section: Motion Primitivesmentioning

confidence: 99%

Visual servoing for teleoperation using a tethered UAV

2017 IEEE International Symposium on Safety, Security and Rescue Robotics (SSRR)

2017

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“…3 right shows that by taking different paths, reaching the goal may have different path-dependent risk. [14], [15] show that longer tether length and more number of contacts in path 1 will introduce more uncertainty, and therefore more risk (state-dependent risk for path 1 may be actually lower since the distance to closest obstacle and visibility are larger). Tether length and number of contacts are also normalized using the potential maximum values given the map size and obstacle density at hand (here, 20 unit length for tether length and 10 for number of contacts).…”

Section: Quantitative Examplesmentioning

confidence: 99%

Explicit Motion Risk Representation

2019 IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR)

2019

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This paper presents a formal definition and explicit representation of robot motion risk. Currently, robot motion risk has not been formally defined, but has already been used in motion and path planning. Risk is either implicitly represented as model uncertainty using probabilistic approaches, where the definition of risk is somewhat avoided, or explicitly modeled as a simple function of states, without a formal definition. In this work, we provide formal reasoning behind what risk is for robot motion and propose a formal definition of risk in terms of a sequence of motion, namely path. Mathematical approaches to represent motion risk are also presented, which is in accordance with our risk definition and properties. The definition and representation of risk provide a meaningful way to evaluate or construct robot motion or path plans. The understanding of risk is even of greater interest for the search and rescue community: the deconstructed environments cast extra risk onto the robot, since they are working under extreme conditions. A proper risk representation has the potential to reduce robot failure in the field.

“…Another important reason for having a tether is to provide extended battery duration [7] and reliable wired communication. Tether could also be used to provide accurate localization of the UAV in GPS-denied environments and where vision-based exteroception is also not available [8]. Fig.…”

Section: Introductionmentioning

confidence: 99%

Benchmarking Tether-based UAV Motion Primitives

2019 IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR)

2019

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This paper proposes and benchmarks two tetherbased motion primitives for tethered UAVs to execute autonomous flight with proprioception only. Tethered UAVs have been studied mainly due to power and safety considerations. Tether is either not included in the UAV motion (treated same as free-flying UAV) or only in terms of station-keeping and highspeed steady flight. However, feedback from and control over the tether configuration could be utilized as a set of navigational tools for autonomous flight, especially in GPS-denied environments and without vision-based exteroception. In this work, two tether-based motion primitives are proposed, which can enable autonomous flight of a tethered UAV. The proposed motion primitives are implemented on a physical tethered UAV for autonomous path execution with motion capture ground truth. The navigational performance is quantified and compared. The proposed motion primitives make tethered UAV a mobile and safe autonomous robot platform. The benchmarking results suggest appropriate usage of the two motion primitives for tethered UAVs with different path plans.