System Design of a Tethered Robotic Explorer (TReX) for 3D Mapping of Steep Terrain and Harsh Environments

McGarey, Patrick; Pomerleau, François; Barfoot, Timothy D.

doi:10.1007/978-3-319-27702-8_18

Cited by 21 publications

(17 citation statements)

References 10 publications

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“…The operational concept for the TReX system is shown in Figure . McGarey et al () first introduced TReX as a system that can both rotate in place regardless of the direction of applied tension due to a passively rotating tether arm, and generate 3D scans of the environment through tether spool rotation. The advanced mobility of the platform allows for turning in place and driving laterally on steep terrain provided sufficient wheel traction.…”

Section: System Design Of Trexmentioning

confidence: 99%

“…In this field report, we detail the system design of TReX (originally introduced in McGarey, Pomerleau, and Barfoot (), draw comparisons to prior tethered systems, and evaluate the system in a field deployment to an open‐pit gravel mine, where the robot was piloted on steep, cluttered terrain to map exposed bed rock as shown in Figure . Mapping relies on a two‐dimensional (2D) lidar mounted to a rotating tether spool to produce scans of the environment as TReX drives and deploys tether.…”

Section: Introductionmentioning

confidence: 99%

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Developing and deploying a tethered robot to map extremely steep terrain

McGarey

Yoon

Tang

et al. 2018

Journal of Field Robotics

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Mobile robots outfitted with a supportive tether are ideal for gaining access to extreme environments for mapping when human or remote observation is not possible. This paper is a field report covering both the development and field testing of our Tethered Robotic eXplorer (TReX) to map a steep, tree-covered rock outcrop in a gravel mine. TReX is a mobile robot designed for the purpose of mapping extremely steep and cluttered environments for geologic and infrastructure inspection. In comparison to other systems, our design improves tethered mobility by enabling rotational freedom on steep slopes using a center-pivoting tether management payload. To map the terrain, we leverage the rotation of an actuated tether spool with an attached two-dimensional (2D) lidar, which rotates to both manage tether and produce 3D scans. Given that mapping requires vehicle motion, we also evaluate two existing, real-time approaches to estimate the trajectory of the robot and rectify motion distortion from individual scans before alignment into the map: (a) a continuous-time, lidar-only approach that handles asynchronous measurements using a physically motivated, constant-velocity motion prior, and (b) a method that computes visual odometry from streaming stereo images to use as a motion estimate during scan collection. Once rectified, individual scans are matched to the global map by an efficient variant of the Iterative Closest Point (ICP) algorithm. Our results include a comparison of estimated maps and trajectories to ground truth (measured by a remote survey station), an example of mapping in highly cluttered terrain, and lessons learned from the design and deployment of TReX.

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Section: System Design Of Trexmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Developing and deploying a tethered robot to map extremely steep terrain

McGarey

Yoon

Tang

et al. 2018

Journal of Field Robotics

Self Cite

View full text Add to dashboard Cite

show abstract

“…A four-wheeled parent rover waits near the edge and the twowheeled child rover explores the steep terrain. [17,18] made a tethered vehicle that can explore a steep terrain and create a 3D map of the environment.…”

Section: Introductionmentioning

confidence: 99%

UAV/UGV Autonomous Cooperation: UAV assists UGV to climb a cliff by attaching a tether

Miki

Khrapchenkov

Hori

2019

2019 International Conference on Robotics and Automation (ICRA)

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This paper proposes a novel cooperative system for an Unmanned Aerial Vehicle (UAV) and an Unmanned Ground Vehicle (UGV) which utilizes the UAV not only as a flying sensor but also as a tether attachment device. Two robots are connected with a tether, allowing the UAV to anchor the tether to a structure located at the top of a steep terrain, impossible to reach for UGVs. Thus, enhancing the poor traversability of the UGV by not only providing a wider range of scanning and mapping from the air, but also by allowing the UGV to climb steep terrains with the winding of the tether. In addition, we present an autonomous framework for the collaborative navigation and tether attachment in an unknown environment. The UAV employs visual inertial navigation with 3D voxel mapping and obstacle avoidance planning. The UGV makes use of the voxel map and generates an elevation map to execute path planning based on a traversability analysis. Furthermore, we compared the pros and cons of possible methods for the tether anchoring from multiple points of view. To increase the probability of successful anchoring, we evaluated the anchoring strategy with an experiment. Finally, the feasibility and capability of our proposed system were demonstrated by an autonomous mission experiment in the field with an obstacle and a cliff.

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“…In addition, due to the presence of obstacles and cables, certain positions can be reached by robot only under specific robot cable configurations. Under many circumstances, multiple tethered robots have to cooperate and work together in a shared workspace [4,5,7,3], which introduces more constraints to the planning and control problems. More specifically, in the large-scale, multi-robot 3D Printing system [3], the tethers are indispensable to deliver the fresh concrete from the mixer to the print nozzle.…”

Section: Introductionmentioning

confidence: 99%

“…More specifically, in the large-scale, multi-robot 3D Printing system [3], the tethers are indispensable to deliver the fresh concrete from the mixer to the print nozzle. Consider also the cable-cable interaction and robot-cable interaction when multiple tethered robots are deployed for terrain and harsh environment exploration [4,5,7]. It is important to make sure that the cables are not entangled while the robots move to their target positions, considering the above mentioned interactions and obstacle avoidance.…”

Section: Introductionmentioning

confidence: 99%

Planning coordinated motions for tethered planar mobile robots

Zhang

Pham

2019

Robotics and Autonomous Systems

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This paper considers the motion planning problem for multiple tethered planar mobile robots. Each robot is attached to a fixed base by a flexible cable. Since the robots share a common workspace, the interactions amongst the robots, cables, and obstacles pose significant difficulties for planning. Previous works have studied the problem of detecting whether a target cable configuration is intersecting (or entangled). Here, we are interested in the motion planning problem: how to plan and coordinate the robot motions to realize a given non-intersecting target cable configuration. We identify four possible modes of motion, depending on whether (i) the robots move in straight lines or following their cable lines; (ii) the robots move sequentially or concurrently. We present an in-depth analysis of Straight & Concurrent, which is the most practically-interesting mode of motion. In particular, we propose algorithms that (a) detect whether a given target cable configuration is realizable by a Straight & Concurrent motion, and (b) return a valid coordinated motion plan. The algorithms are analyzed in detail and validated in simulations and in a hardware experiment.

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System Design of a Tethered Robotic Explorer (TReX) for 3D Mapping of Steep Terrain and Harsh Environments

Cited by 21 publications

References 10 publications

Developing and deploying a tethered robot to map extremely steep terrain

Developing and deploying a tethered robot to map extremely steep terrain

UAV/UGV Autonomous Cooperation: UAV assists UGV to climb a cliff by attaching a tether

Planning coordinated motions for tethered planar mobile robots

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