Sensor Placement
We study the problem of placing sensors yielding bearing measurements with bounded noise, in a square workspace to localize a stationary target upto a desired uncertainty. We show that by placing sensors on a triangular grid, we can guarantee that the target's uncertainty is within a constant-factor of that of an (unknown) optimal algorithm for any true target location and any set of measurements obtained. We show that this estimate can be obtained by activating a small number of sensors and the total number of sensors placed by our algorithm is at most a constant-factor as that of an optimal algorithm.
- Sensor Placement and Selection for Bearing Sensors with Bounded Uncertainty.
P. Tokekar and V. Isler. Technical Report [draft]
Optimal Coverage Tour
We study the problem of optimally covering a set of regions in a plane by a sensor with limited sensing radius. In our application, these regions correspond to those likely to contain the fish in the lake. This problem is a generalization of TSP with neighborhoods; in addition to finding the optimal order to visit each region, we also have to determine optimal coverage patterns within each region. We present a simple constant factor (a+b)-approximation for the general case, and a 3-approximation for the special case when the regions are rectangles and touching the boundary of a convex polygon.
- Coverage and Active Localization for Monitoring Invasive Fish with an Autonomous Boat.
P. Tokekar, E. Branson, J. Vander Hook, and V. Isler. IEEE Robotics and Automation Magazine, 2012. Note: conditionally accepted.
Active Localization Using Bearing Sensors
Multiple measurements are required to precisely localize a target using a bearing sensor. Uncertainty in the target's estimate depends on the measurement locations; some locations are more "informative" than others. Further, this information is only revealed in an online fashion: each new measurement yields more information about the target. We study the problem of choosing such informative sensing locations in an online fashion, seeking theoretical performance guarantees.
- Cautious Greedy Strategy for Bearing-based Active Localization: Experiments and Theoretical Analysis
J. Vander Hook, P. Tokekar, and V. Isler. In Proc. IEEE Int. Conf. on Robotics and Automation, 2012. Note: to appear. [pdf][.bib][tech report] - Active Target Localization for Bearing Based Robotic Telemetry.
P. Tokekar, J. Vander Hook, and V. Isler. In Proc. IEEE/RSJ Int. Conf. on Intelligent Robots and Systems, 2011. [pdf][.bib]
Robotic System for Monitoring Carp
We are working with researchers from the Dept. of Fisheries to develop a network of autonomous robotic boats and mobile robots to monitor radio-tagged fish in lakes (and on frozen lakes!). As part of our research, we study interesting algorithmic problems in search, coverage and tracking.
- Local-Search Strategy for Multi-Modal, Multi-Target, Active Localization of Invasive Fish.
J. Vander Hook, P. Tokekar, E. Branson, P. Bajer, P. Sorensen, and V. Isler In International Symposium on Experimental Robotics, 2012. Note: to appear. - A Robotic System for Monitoring Carp in Minnesota Lakes.
P. Tokekar, D. Bhadauria, A. Studenski, and V. Isler. Journal of Field Robotics, 2010. [pdf][.bib][link]
For further details see the project page.
Energy Efficient Motion Planning for Mobile Robots
For battery-powered mobile robots to operate for long periods of time, it is critical to optimize their motion so as to minimize energy consumption. The driving motors are a major source of power consumption. We studied the problem of finding energy-optimal velocity profiles for car-like robots given a path to travel. We have also recently investigated the problem of energy-efficient, time-limited path planning of a solar powered robot embedded in a terrestrial environment.
- Energy Efficient Path Planning for Solar Powered Mobile Robots in Complex Environments.
P. A. Plonski, P. Tokekar, and V. Isler. In International Symposium on Experimental Robotics, 2012. Note: to appear. - Energy-Optimal Velocity Profiles for Car-Like Robots.
P. Tokekar, N. Karnad, and V. Isler. In Proc. IEEE Int. Conf. on Robotics and Automation, 2011. [pdf][.bib]