Low cost underwater robot sensor suite

One of the most expensive parts of underwater robotics is the sensors. This paper looks at modifying off the shelf components to create a sensor suite on a small budget. A big saving is made with sonar using a cheap commercial product to create a four sonar array. A depth sensor and acceleration navigation system are also developed.

Network resilience in low-resource mobile wireless sensor networks

Wireless sensor networks (WSNs) are deployed in numerous mission critical applications in which the network needs to remain active for as long as possible while delivering quality information to a base station. However, WSNs suffer from a wide range of attacks due to their limited processing and energy capabilities. Their resiliency, however, depends on fast recovery from such attacks being achieved. In recent work, the authors developed and implemented clustering, reprogramming and authentication protocols involved in recovering stationary WSNs with low resources. In this paper, we determine the additional resources required in implementing these protocols in a mobile WSN.

We present recovery protocols on TinyOS motes for a low-resourced, mobile deployment. We describe the issues we encountered in the implementation. We present times, RAM and ROM needed to run the recovery protocols and compare these with the stationary case, demonstrating that the additional cost of reprogramming in a mobile WSN is less than 25% of that in a stationary WSN and the additional cost of re-clustering in a mobile WSN is less than 9% of that in a stationary WSN. Authentication has an insignificant cost increase.

Optimal sensor placement in linear arrays : part I - AoA based localization

In this paper, we examine the optimal linear separation requirements for AoA sensors, in order to achieve the best performance in estimating the position of a target subjected to noisy measurements. Cramer-Rao inequality and the corresponding Fisher information matrix are used to analyze the sensor-target geometry, in order to characterize localization performance with respect to the linear spacial distribution of sensors.

Optimal sensor placement in range based localization for linear arrays

This paper investigates the linear separation requirements for range sensors in order to achieve the optimal performance in estimating the position of a target from multiple and typically noisy sensor measurements. We analyze the sensor-target geometry in terms of the Cramer-Rao inequality and the corresponding Fisher information matrix, in order to characterize localization performance with respect to the linear special distribution.

Optimal sensor placement and measurement of wind for water quality studies in urban reservoirs

We collaborate with environmental scientists to study the hydrodynamics and water quality in an urban district, where the surface wind distribution is an essential input but undergoes high spatial and temporal variations due to the complex urban landform created by surrounding buildings. In this work, we study an optimal sensor placement scheme to measure the wind distribution over a large urban reservoir with a limited number of wind sensors. Unlike existing sensor placement solutions that assume Gaussian process of target phenomena, this study measures the wind which inherently exhibits strong non-Gaussian yearly distribution. By leveraging the local monsoon characteristics of wind, we segment a year into different monsoon seasons which follow a unique distribution respectively. We also use computational fluid dynamics to learn the spatial correlation of wind in the presence of surrounding buildings. The output of sensor placement is a set of the most informative locations to deploy the wind sensors, based on the readings of which we can accurately predict the wind over the entire reservoir surface in real time. 10 wind sensors are finally deployed around or on the water surface of an urban reservoir. The in-field measurement results of more than 3 months suggest that the proposed sensor placement and spatial prediction approach provides accurate wind measurement which outperforms the state-of-the-art Gaussian model based or interpolation based approaches.

Sensor placement and measurement of wind for water quality studies in urban reservoirs

We study the water quality in an urban district, where the surface wind distribution is an essential input but undergoes high spatial and temporal variations due to the impact of surrounding buildings. In this work, we develop an optimal sensor placement scheme to measure the wind distribution over a large urban reservoir using a limited number of wind sensors. Unlike existing solutions that assume Gaussian process of target phenomena, this study measures the wind that inherently exhibits strong non-Gaussian yearly distribution. By leveraging the local monsoon characteristics of wind, we segment a year into different monsoon seasons that follow a unique distribution respectively. We also use computational fluid dynamics to learn the spatial correlation of wind. The output of sensor placement is a set of the most informative locations to deploy the wind sensors, based on the readings of which we can accurately predict the wind over the entire reservoir in real time. Ten wind sensors are deployed. The in-field measurement results of more than 3 months suggest that the proposed sensor placement and spatial prediction scheme provides accurate wind measurement that outperforms the state-of-the-art Gaussian model based on interpolation-based approaches.

Minimal force jump within human and assistive robot cooperation

When an assistant robotic manipulator cooperatively performs a task with a human and the task is required to be highly reliable, then fault tolerance is essential. To achieve the fault tolerance force within the human robot cooperation, it is required to map the effects of the faulty joint of the robot into the manipulator’s healthy joints’ torque space and the human force. The objective is to optimally maintain the cooperative force within the human robot cooperation. This paper aims to analyze the fault tolerant force within the cooperation and two frameworks are proposed. Then they have been validated through a fault scenario. Finally, the minimum force jump which is the optimal fault tolerance has been achieved.

Formation control of weak autonomous robots

Formation of autonomous mobile robots to an arbitrary geometric pattern in a distributed fashion is a fundamental problem in formation control. This paper presents a new fully distributed, memoryless (oblivious) algorithm to the formation control problem via distributed optimization techniques. The optimization minimizes an appropriately defined difference function between the current robot distribution and target geometric pattern. The optimization processes are performed independently by individual robots in their local coordinate system. A movement strategy derived from the results of the distributed optimizations guarantees that every movement makes the current robot configuration approaches the target geometric pattern until the final pattern is reached.

Terminal approach navigation for autonomous robots in a sensory network

In this paper we present a technique based on precision guidance approach for the sensor delivery and reception problem between two mobile robots. A slave robot is employed to collect sensors and slack them on a tray carried by the mobile master robot. We define the terminal attitude of the slave robot with respect to the master and present a LQR control approach to solving the problem of achieving a desired terminal approach angle necessary for the appropriate sensor delivery. The approach criteria is defined in terms of both minimizing the miss distance and controlling the slave robot's body attitude with respect to the master robot at the terminal point.

Placing sensors for area coverage in a complex environment by a team of robots

Existing solutions to carrier-based sensor placement by a single robot in a bounded unknown Region of Interest (ROI) do not guarantee full area coverage or termination. We propose a novel localized algorithm, named Back-Tracking Deployment (BTD). To construct a full coverage solution over the ROI, mobile robots (carriers) carry static sensors as payloads and drop them at the visited empty vertices of a virtual square, triangular, or hexagonal grid. A single robot will move in a predefined order of directional preference until a dead end is reached. Then it back-tracks to the nearest sensor adjacent to an empty vertex (an "entrance" to an unexplored/uncovered area) and resumes regular forward movement and sensor dropping from there. To save movement steps, the back-tracking is carried out along a locally identified shortcut. We extend the algorithm to support multiple robots that move independently and asynchronously. Once a robot reaches a dead end, it will back-track, giving preference to its own path. Otherwise, it will take over the back-track path of another robot by consulting with neighboring sensors. We prove that BTD terminates within finite time and produces full coverage when no (sensor or robot) failures occur. We also describe an approach to tolerate failures and an approach to balance workload among robots. We then evaluate BTD in comparison with the only competing algorithms SLD [Chang et al. 2009a] and LRV [Batalin and Sukhatme 2004] through simulation. In a specific failure-free scenario, SLD covers only 40-50% of the ROI, whereas BTD covers it in full. BTD involves significantly (80%) less robot moves and messages than LRV.

A haptically enabled CAN-based steering wheel controller

As the portable entertainment and mobility technologies migrate into the car, driver distraction has become recognized as a major factor in road crashes around the world. To help alert drivers to their distraction, active safety technologies such as lane departure warning systems and collision avoidance systems are being implemented. One issue with the implementation of yet another technology into the vehicle is how to cut through the competing demands of the mobile phone, navigation systems and other technologies. Haptic alerts present just such a method that may enable the system to short-circuit the normal auditory or visual communication channels. This paper presents a low cost haptic steering wheel controller that has been designed developed and tested and may be used as a communication device by a lane departure, collision avoidance, or other type of safety system.

Absence makes the heart grow fonder SPOKEN WORD

Absence Makes the Heart Grow Fonder is a female voice (British) saying the proverb where the voice has been manipulated to sound arrhythmic and robotic. A good piece for a non-human (robot or like) saying a proverb that goes to the heart of sentience.

Methods of usability evaluations of mobile devices

The usability of applications designed and developed for mobile devices integral user experience, particularly for current touch-screen mobile devices. This conceptual paper provides a profile of the ways in which mobile device usability evaluation methods are being adapted to better reflect technological. With an increasing capacity for greater user interactivity through a range of tasks and in a variety of contexts, the importance and impact of mobile device context-of-use components is of particular interest to researchers. This requires a need for a shift in evaluation method paradigms with a particular focus on methods involving the user, as part of the overall development process. Having a better understanding of the context-of-use may contribute to improvements in mobile device usability and the overall user experience.