D.M. Wilkes

Mobile robot localization using an electronic compass for corridor environment

This paper proposes a simple method for localization using an electronic compass. Electronic compasses are often used to detect the heading of mobile robots. However, electronic compasses have one drawback when used inside a building: they can easily be disturbed by electromagnetic sources (e.g., power lines) or large ferro-magnetic structures (e.g., bookshelves). However, this paper introduces another indoor application of electronic compasses. We take advantage of the magnetic field disturbances by using them as distinctive place recognition signatures. We first gather information about the changing heading as our robot travels along the hallway outside the lab, and then store this information. As the robot traverses the hallway, it gathers the information from the electronic compass and matches it with the pre-stored data. If a match is found, the robot can determine its current position. We use a sequential least-squares approximation approach for matching the signature. The simulation results will show that the robot can distinguish its location by using these signatures.

ISAC: foundations in human-humanoid interaction

The authors describe their humanoid robotic system, ISAC (Intelligent Soft-Arm Control), and their approach to human-humanoid interaction (HHI). They present a software architecture called the Intelligent Machine Architecture (IMA) and two high-level agents (the Human agent and the Self agent) within their HHI framework.

Sonar behavior-based fuzzy control for a mobile robot

This paper describes how fuzzy control can be applied to a sonar-based mobile robot. Behavior-based fuzzy control for HelpMate behaviors was designed using sonar sensors. The fuzzy controller provides a mechanism for combining sensor data from all sonar sensors which present different information. The behavior-based approach is implemented as an individual high priority behavior. The highest level behavior is called the task-oriented behavior, which consists of two subtasks, wall following and goal seeking. The middle level behavior is obstacle avoidance. The lowest level is an emergency behavior. Each behavior was built as an atomic agent based on the intelligent machine architecture (IMA). The results demonstrate that each behavior works correctly. The HelpMate robot can follow the wall, go to the goal, and avoid obstacles detected by the sonar sensors.

The Caenorhabditis elegans Choline Transporter CHO-1 Sustains Acetylcholine Synthesis and Motor Function in an Activity-Dependent Manner

Cholinergic neurotransmission supports motor, autonomic, and cognitive function and is compromised in myasthenias, cardiovascular diseases, and neurodegenerative disorders. Presynaptic uptake of choline via the sodium-dependent, hemicholinium-3-sensitive choline transporter (CHT) is believed to sustain acetylcholine (ACh) synthesis and release. Analysis of this hypothesis in vivo is limited in mammals because of the toxicity of CHT antagonists and the early postnatal lethality of CHT−/− mice (Ferguson et al., 2004). In Caenorhabditis elegans, in which cholinergic signaling supports motor activity and mutant alleles impacting ACh secretion and response can be propagated, we investigated the contribution of CHT (CHO-1) to facets of cholinergic neurobiology. Using the cho-1 promoter to drive expression of a translational, green fluorescent protein-CHO-1 fusion (CHO-1:GFP) in wild-type and kinesin (unc-104) mutant backgrounds, we establish in the living nematode that the transporter localizes to cholinergic synapses, and likely traffics on synaptic vesicles. Using embryonic primary cultures, we demonstrate that CHO-1 mediates hemicholinium-3-sensitive, high-affinity choline uptake that can be enhanced with depolarization in a Ca2+-dependent manner supporting ACh synthesis. Although homozygous cho-1 null mutants are viable, they possess 40% less ACh than wild-type animals and display stress-dependent defects in motor activity. In a choline-free liquid environment, cho-1 mutants demonstrate premature paralysis relative to wild-type animals. Our findings establish a requirement for presynaptic choline transport activity in vivo in a model amenable to a genetic dissection of CHO-1 regulation.

TOWARD SOCIALLY INTELLIGENT SERVICE ROBOTS

In the Intelligent Robotics Laboratory at Vanderbilt University, we seek to develop service robots with a high level of social intelligence and interactivity. In order to achieve this goal, we have identified two main issues for research. The first issue is how to achieve a high level of interaction between the human and the robot. This has lead to the formulation of our philosophy of Human Directed Local Autonomy (HuDL), a guiding principle for research, design, and implementation of service robots. The motivation for integrating humans into a service robot system is to take advantage of human intelligence and skill. Human intelligence can be used to interpret robot sensor data, eliminating computationally expensive and possibly error-prone automated analyses. Human skill is a valuable resource for trajectory and path planning as well as for simplifying the search process. In this article, we present our plans for integrating humans into a service robot system. We present our paradigm for human-robot int...

In‐process gap detection in friction stir welding

Purpose – This paper aims to investigate methods of implementing in‐process fault avoidance in robotic friction stir welding (FSW).Design/methodology/approach – Investigations into the possibilities for automatically detecting gap‐faults in a friction stir lap weld were conducted. Force signals were collected from a number of lap welds containing differing degrees of gap faults. Statistical analysis was carried out to determine whether these signals could be used to develop an automatic fault detector/classifier.Findings – The results demonstrate that the frequency spectra of collected force signals can be mapped to a lower dimension through discovered discriminant functions where the faulty welds and control welds are linearly separable. This implies that a robust and precise classifier is very plausible, given force signals.Research limitations/implications – Future research should focus on a complete controller using the information reported in this paper. This should allow for a robotic friction stir ...

Misalignment detection and enabling of seam tracking for friction stir welding

Abstract This paper describes a technique for determining the position of a friction stir welding (FSW) tool with respect to the weld seam during welding. Forces are used as a feedback signal, and a general regression neural network is trained to predict offset position given weld forces. Experimental results demonstrate the accuracy of the developed position predictor. This technique is proposed for online misalignment detection or as a position estimator for in-process tracking of the weld seam for FSW and robotic FSW.

Toward perception-based navigation using EgoSphere

A method for perception-based egocentric navigation of mobile robots is described. Each robot has a local short-term memory structure called the Sensory EgoSphere (SES), which is indexed by azimuth, elevation, and time. Directional sensory processing modules write information on the SES at the location corresponding to the source direction. Each robot has a partial map of its operational area that it has received a priori. The map is populated with landmarks and is not necessarily metrically accurate. Each robot is given a goal location and a route plan. The route plan is a set of via-points that are not used directly. Instead, a robot uses each point to construct a Landmark EgoSphere (LES) a circular projection of the landmarks from the map onto an EgoSphere centered at the via-point. Under normal circumstances, the LES will be mostly unaffected by slight variations in the via-point location. Thus, the route plan is transformed into a set of via-regions each described by an LES. A robot navigates by comparing the next LES in its route plan to the current contents of its SES. It heads toward the indicated landmarks until its SES matches the LES sufficiently to indicate that the robot is near the suggested via-point. The proposed method is particularly useful for enabling the exchange of robust route informa-tion between robots under low data rate communications constraints. An example of such an exchange is given.

Multi-agent system for a human-friendly robot

At the Center for Intelligent Systems, we are working on human robot interaction (HRI). We present our approach for HRI. Our goals for HRI are to allow the human to influence the robots actions in some way and acquire feedback about the robots internal state. Additionally, we would like the robot to confirm the humans input and request the humans assistance if necessary. To achieve our goals, we are developing two intelligent agents: the human agent and the self agent. The human agent encapsulates what the robot knows about the human. The self agent maintains knowledge about the internal state of the robot and communicates with the human. We performed a preliminary demonstration of the system, in which the human could have limited conversation with the robot, a dual-armed humanoid. This limited conversation included commands to the robot and queries about the robots abilities and internal state.

A low-cost, DSP-based, intelligent vision system for robotic applications

In this paper we present the design and implementation of a novel low-cost active vision system for robotic applications. The system is comprised of two parts: A 4-DOF trinocular active camera head and a DSP-based image acquisition and processing board. Design issues and tradeoffs are discussed. The performance of the system is evaluated by running an edge-based object tracking algorithm that is also presented in this paper. Experimental results show that the system is capable of tracking objects at 30 frames/sec.