Making gestures easy for imaging systems to reliably recognize often comes at the expense of user effort. But what is the impact of increasing a gesture's effort, even slightly, on user preference? We investigate physical effort, system reliability, and user satisfaction in two experiments. The first explores eight basic command gestures. Participants preferred the less effortful gestures in two of the three easy-difficult gesture pairs when they perceived the difference in effort to be significantly different. The second experiment explores two separate three-dimensional pointing and selection conditions that differ only in the movement distance required to finish the task. In both experiments, there is a significant negative correlation between a gesture's effort and its appeal. The results show the great impact that effort has on a user's willingness to utilize the system. The findings provide evidence that the trade-off between user effort and system reliability must be carefully considered to build an effective gesture interface.

Creating training simulators for orthopedic surgery presents unique and largely unexplored engineering challenges. One of these challenges is simulating both the large forces and subtle haptic feedback involved in drilling into bone. This paper involves a hybrid reality wire navigation simulator that combines a physical drill and plastic foam bone surrogate with 3-D graphics to mimic the radiographic imaging often used in a common surgical task. This paper describes experiments to test the simulator's face, content, and construct validity, as well as the precision of the motion-tracking system. The results suggest that the simulator has sufficient face validity to engage trainees and recreates the critical aspects of the wire navigation task. Experimental simulator trials reveal time and accuracy differentials between experts and novices, suggesting construct validity. The results also show that the tracking system is accurate within 3.6 mm.

Robotic exploration is an excellent method for obtaining information about sites too dangerous for people to explore. The operator's understanding of the environment depends on the rover returning useful information. Robotic mission bandwidth is frequently constrained, limiting the amount of information the rover can return. This paper explores the tradeoff between information and bandwidth based on two years of observations during a robotic astrobiology field study. The developed theory begins by analyzing the search task conducted by robot operators. This analysis leads to an information optimization model. Important parameters in the model include the value associated with detecting a target, the probability of locating a target, and the bandwidth required to collect the information from the environment. Optimizing the information return between regions creates an image and provides the necessary information while reducing bandwidth. Application of the model to the analyzed field study results in an optimized image that requires 48.3% less bandwidth to collect. The model also predicts several data collection patterns that could serve as the basis of data collection templates for improving mission effectiveness. The developed optimization model reduces the bandwidth necessary to collect information, thus aiding missions in collecting more information from the environment.

Multi-robot systems are particularly useful in tasks that require searching large areas such as planetary science exploration, urban search and rescue, or landmine remediation. In order to overcome the inherent complexity of controlling multiple robots, the user must be able to give high-level, goal driven direction to the robot team. Since human robot interaction is a relatively new discipline, it is helpful to look to existing systems for concepts, analogies, or metaphors that might be utilized in building useful systems. Inspiration from natural decentralized systems guides the development of a computer simulation for stigmergy-based control of multi-robot system, and the interface with which an operator can interact and control mobile robots. In-depth description of the design process includes a description of a basic stigmergy-based control system and an innovative Directed Stigmergy control system that facilitates operator control of the robot team in an interesting and surprisingly effective way.

A clinical breast exam (CBE), in which a nurse or doctor palpates a patient's breast tissue searching for hard lumps, is a recommended annual breast cancer diagnostic for women over 40. Recent advances in training technology have suggested that the sensitivity of this exam can be improved and that clinicians are interested in improving training approaches. Currently researchers have an incomplete understanding of which features of the force pattern an observer must perceive in order to recognize the presence of a tumor. This limitation in our knowledge limits our ability to build more effective simulators that emphasize the specific characteristics of the signal that clinicians must perceive. Three experiments were performed using tissue analogs made from silicone rubber embedded with hard spheres. The size of the balls, their depth and the stiffness of the silicone were varied. The force exerted on a probe indented at regular intervals along the samples revealed the general force profile that a clinician may experience on his or her finger pad when searching for a tumor. Several measures of the force profiles were compared to the salience of the ball within the silicone: the ratio of the response force directly above the sphere to the force response far from the sphere, the rate of change of the force response near the sphere, and difference between the force above and to the side divided by the force to the side. These measures correlated with salience when the ball size and ball depth was varied, but not when the silicone stiffness varied. The results suggest that the relationship between the force profile and the salience of the stimulus is more complex that expected. Once this relationship is more fully understood, new training tools and procedures can be developed to trains clinicians and improve the sensitivity of clinical breast exams.

In the 2006 RoboCup Virtual Rescue competition, teams from different research labs developed methods for controlling teams of mobile robots in a simulated urban search and rescue scenario. This paper reviews the strategies and scores from the top six competitors. The scoring procedure used in this inaugural competition rewards participants for the number of victims found, the amount of area explored in the environment, the quality of the maps created by the robot teams and penalties participants for colliding with a victim or relying on human operators. The analysis of the strategies and scores suggests that the scoring procedure may lead teams to adopt strategies that are not consistent with the needs of a real search and rescue scenario. Individual robot contributions to the system were reviewed to account for the costs associated with adding a robot to the environment, indicating that value added per robot is an important measure that is overlooked. The analysis of the impact of human operator penalties on scoring revealed an overemphasis on fully autonomous robotic systems. The analysis also revealed substantial performance variation, depending on the behavior that was being rewarded, which may indicate a lack of focus for evaluative performance measures of robotic urban search and rescue systems. The competition has the potential to provide influential research in this area if a proper scoring procedure that reflects actual research needs is implemented. In order to ensure that research gains made as a result of the competition process are useful to the application community, it is essential that the rules be tuned to the application needs. It is likely that, as competitions and games are becoming a growing part of the research community, this sensitivity is managed along with the other political, social and interactive demands involved in setting rules for research competitions.

During two weeks of study in September and October of 2004, a science team directed a rover and explored the arid Atacama Desert in Chile. The objective of the mission was to search for life. Over the course of the mission the team gained experience with the rover and the rover became more reliable and autonomous. As a result, the rover/operator system became more effective. Several factors likely contributed to the improvement in science effectiveness including increased experience, more effective search strategies, different science team composition, different science site locations, changes in rover operational capabilities, and changes in the operation interface. However, it is difficult to quantify this effectiveness because science is a largely creative and unstructured task. This study considers techniques that quantify science team performance leading to an understanding of which features of the human-rover system are most effective and which features need further development. Continuous observation of the scientists throughout the mission led to coded transcripts enumerating each scientific statement. This study considers whether six variables correlate with scientific effectiveness. Several of these variables are metrics and ratios related to the daily rover plan, the time spent programming the rover, the number of scientific statements made and the data returned. The results indicate that the scientists created more complex rover plans without increasing the time to create the plans. The total number of scientific statements was approximately equal (2187 versus 2415) for each week. There was a 50% reduction in bytes of returned data between the two weeks resulting in an increase in scientific statements per byte of returned data ratio. Of the original six, the most successful proxies for science effectiveness were the time to program each rover task and the number of scientific statements related to data delivered by the rover. Although both these measures have face validity and were consistent with the results of this experiment, their ultimate empirical utility must be measured further.

When searching a remote environment with a robot, the fundamental constraint on the operator is the bandwidth available to the mission. This paper examines how a science team uses a high bandwidth panorama during a two-year astrobiology field test. Bandwidth directly controls the type and amount of information received by the operator. Given the significance of information and bandwidth to mission success, it is important for human robot interaction analyses to consider bandwidth usage during robotic operations. Insight gained from these analyses can help future missions efficiently use their bandwidth to collect the necessary information from the environment. The analysis first shows that the science team preferentially views certain areas of the panorama based on tile elevation but not based on azimuth. This finding led the analysis to look into what tasks the science team completes while using the panorama. In the context of an astrobiology mission, the most important role of the panorama is to determine the robot's position on orbital images. The secondary task is to determine the general geologic context of the environment. Based on the viewing patterns and associated tasks the analysis produces a list of targets important to mission success. Future research efforts will focus on methods for collecting the information contained in these targets from the environment at a reduced bandwidth cost.

Researchers have previously described a mobile robot, or rover, operator's difficulty in accurately perceiving the rover's tilt and roll, which can lead to rollover accidents. Safe mobile robot navigation and effective mission planning also require an operator to accurately interpret and understand the geometry and scale of features in the rover's environment. This work presents an experiment that measures an observer's ability to estimate height of distant (5-15 m) obstacles given an accurate local model (e.g., within 0-5 m of the rover), a panoramic image, and a physical mock-up of the local terrain. The experimental conditions were intended to represent a best-case scenario for a stopped rover equipped with short base-line stereoscopic cameras. The participants' task was to extrapolate the well-modeled local geometry to monoscopic images of the more distant terrain. The experiment compared two estimation techniques. With the first technique, each observer physically indicated his or her direct estimates of the obstacle distance and height. With the second estimation technique, which we call horizon analysis, the observer indicated the position of the top and bottom of each rock on an image and the height was calculated by measuring the visual angle between the theoretical horizon and the points indicated by the observer. The direct estimation technique overestimated the height of the rocks by an average of 190%; the horizon analysis technique overestimated by 80%. The results suggest that even when provided with a rich set of supplementary and context information, rover operators have significant difficulty in vertically perceiving the scale of distant terrain. The results also suggest that horizon analysis is a more accurate method for determining the height of distant rover navigation obstacles, when the local terrain is nearly level.

Clinical breast examinations (CBE) are an important component in breast cancer screening. Inadequate training of tactile skills may contribute to a low and variable CBE sensitivity range. Based on previous investigations, we investigated adding visual feedback of pressure changes in balloons embedded in silicone under palpation to provide learners with positive confirmation of their performance, thus enhancing confidence in lump detection and improving sensitivity and specificity. The experiment tested the effects of visually augmented training by comparing training groups which receive either: a) no training (only verbal), b) palpation practice without feedback, or c) visually augmented feedback. The experiment utilized signal detection theory and included 18 medical students who completed a pretest, training, and a postest but found no significant differences between the training groups.

Measuring the error introduced by the machine and human in a man-machine system is an important step in understanding and improving the system. Two experiments assessed the error from the total system in length measurements and shape classification. A separate analysis calculated the error introduce by the camera. The average error for length measurements was 2.33 pixels with a standard deviation of 2.399. The error in edge location introduce by the camera was 5-10 pixels. This indicates that humans generally are good at measuring lengths, but have difficulty near the threshold of resolution. Results from the classification task indicate that humans have lower then expected intra and inter geologist consistency. The study indicates that increasing the resolution of the camera system increases length measurement accuracy and that training may be the best way to improve classification consistency.

The purpose of Project Pioneer is to develop an exploratory robot capable of creating a three-dimensional photo-realistic map of the inside of the damaged Chernobyl nuclear reactor, measure the environmental and radioactive conditions, and collect samples of concrete from the physical structure to determine its mechanical stability. This paper describes the virtual reality interface for Pioneer's three-dimensional mapping system. This interface addresses a wide variety of technical challenges, including several that are unique to the hostile Chernobyl environment.

Hand posture and force, which define aspects of the way an object is grasped, are features of robotic manipulation. A means for specifying these grasping "flavors" has been developed that uses an instrumented glove equipped with joint and force sensors. The new grasp specification system will be used at the Pennsylvania State University (Penn State) in a Virtual Reality based Point-and-Direct (VR-PAD) robotics implementation. Here, an operator gives directives to a robot in the same natural way that human may direct another. Phrases such as "put that there" cause the robot to define a grasping strategy and motion strategy to complete the task on its own. In the VR-PAD concept, pointing is done using virtual tools such that an operator can appear to graphically grasp real items in live video. Rather than requiring full duplication of forces and kinesthetic movement throughout a task as is required in manual telemanipulation, hand posture and force are now specified only once. The grasp parameters then become object flavors. The robot maintains the specified force and hand posture flavors for an object throughout the task in handling the real workpiece or item of interest. In the Computer integrated Manufacturing (CIM) Laboratory at Penn State, hand posture and force data were collected for manipulating bricks and other items that require varying amounts of force at multiple pressure points. The feasibility of measuring desired grasp characteristics was demonstrated for a modified Cyberglove impregnated with Force-Sensitive Resistor (FSR) (pressure sensors in the fingertips. A joint/force model relating the parameters of finger articulation and pressure to various lifting tasks was validated for the instrumented "wired" glove. Operators using such a modified glove may ultimately be able to configure robot grasping tasks in environments involving hazardous waste remediation, flexible manufacturing, space operations and other flexible robotics applications. In each case, the VR-PAD approach will finesse the computational and delay problems of real-time multiple-degree-of-freedom force feedback telemanipulation.