Andrew Drenner

View-independent human motion classification using image-based reconstruction

We introduce in this paper a novel method for employing image-based rendering to extend the range of applicability of human motion and gait recognition systems. Much work has been done in the field of human motion and gait recognition, and many interesting methods for detecting and classifying motion have been developed. However, systems that can robustly recognize human behavior in real-world contexts have yet to be developed. A significant reason for this is that the activities of humans in typical settings are unconstrained in terms of the motion path. People are free to move throughout the area of interest in any direction they like. While there have been many good classification systems developed in this domain, the majority of these systems have used a single camera providing input to a training-based learning method. Methods that rely on a single camera are implicitly view-dependent. In practice, the classification accuracy of these systems often becomes increasingly poor as the angle between the camera and the direction of motion varies away from the training view angle. As a result, these methods have limited real-world applications, since it is often impossible to limit the direction of motion of people so rigidly. We demonstrate the use of image-based rendering to adapt the input to meet the needs of the classifier by automatically constructing the proper view (image), that matches the training view, from a combination of arbitrary views taken from several cameras. We tested the method on 162 sequences of video data of human motions taken indoors and outdoors, and promising results were obtained.

Optimal Camera Placement for Automated Surveillance Tasks

Camera placement has an enormous impact on the performance of vision systems, but the best placement to maximize performance depends on the purpose of the system. As a result, this paper focuses largely on the problem of task-specific camera placement. We propose a new camera placement method that optimizes views to provide the highest resolution images of objects and motions in the scene that are critical for the performance of some specified task (e.g. motion recognition, visual metrology, part identification, etc.). A general analytical formulation of the observation problem is developed in terms of motion statistics of a scene and resolution of observed actions resulting in an aggregate observability measure. The goal of this system is to optimize across multiple cameras the aggregate observability of the set of actions performed in a defined area. The method considers dynamic and unpredictable environments, where the subject of interest changes in time. It does not attempt to measure or reconstruct surfaces or objects, and does not use an internal model of the subjects for reference. As a result, this method differs significantly in its core formulation from camera placement solutions applied to problems such as inspection, reconstruction or the Art Gallery class of problems. We present tests of the system’s optimized camera placement solutions using real-world data in both indoor and outdoor situations and robot-based experimentation using an all terrain robot vehicle-Jr robot in an indoor setting.

Multi-Camera Human Activity Monitoring

With the proliferation of security cameras, the approach taken to monitoring and placement of these cameras is critical. This paper presents original work in the area of multiple camera human activity monitoring. First, a system is presented that tracks pedestrians across a scene of interest and recognizes a set of human activities. Next, a framework is developed for the placement of multiple cameras to observe a scene. This framework was originally used in a limited X, Y, pan formulation but is extended to include height (Z) and tilt. Finally, an active dual-camera system for task recognition at multiple resolutions is developed and tested. All of these systems are tested under real-world conditions, and are shown to produce usable results.

Loper: A quadruped-hybrid stair climbing robot

The purpose of this paper is to describe the Loper, a multi-purpose robotic platform under development at the University of Minnesotas Center for Distributed Robotics. Lepers unique Tri-lobe wheel design and highly compliant chassis make the platform especially suited for overcoming many of the challenges associated with search operations in urban settings. The mechanically simple design and use of commercially available components make Loper easily maintainable. The platform also features long operational time, onboard sensor processing, dedicated motion control, and four reconfigurable sensor bays.

Mobility enhancements to the Scout robot platform

When a distributed robotic system is assigned to perform reconnaissance or surveillance, restrictions inherent to the design of an individual robot limit the systems performance in certain environments. Finding an ideal portable robotic platform capable of deploying and returning information in spatially restrictive areas is not a simple task. The Scout robot, developed at the University of Minnesota, is a viable robotic platform for these types of missions. The small form factor of the Scout allows for deployment, placement, and concealment of a team of robots equipped with a variety of sensory packages. However, the design of the Scout requires a compromise in power, sensor types, locomotion, and size; together these factors prevent an individual Scout from operating ideally in some environments. Several attempts to address these deficiencies have been implemented and are discussed. Among the prototype solutions are actuating wheels, allowing the Scout to increase ground clearance in varying terrains, a grappling hook enabling the Scout to obtain a position of elevated observation, and infrared emitters to facilitate low light operation.

Communication and mobility enhancements to the Scout robot

Small scale distributed robotic systems are ideal for tasks that larger, more expensive robots may not be able to undertake such as surveillance or inspection in enclosed areas. Small scale robots also have the advantage of being easily portable to an area of interest. However, the advantages related to the small size and portability cause an increase in the complexity of development. In addition, the more pronounced effects of interacting with the environment in terms of mobility and communications lead to robotic systems of limited functionality. In order to address such deficiencies, several novel developments and improvements have been made to the Scout robot, which will be discussed. These improvements include the development of a communication relay system facilitating longer distance operation, an improved actuating wheel system increasing the Scouts mobility and a grappling hook system to elevate the Scout. By enhancing the Scout robotic team in this way, the functional use of the team is expanded, allowing more practical use.

Docking station relocation for maximizing longevity of distributed robotic teams

Distributed robotic teams have long been touted as potential means to avoid sending humans into harmful situations. The ability of robotic teams to operate for extended periods without the fatigue human teams can experience, coupled with the ability to transport a variety of sensing and manipulation equipment and reducing costs of operation make them an attractive solution. Limited sensing capabilities, power, and mobility of individual robotic platforms can be overcome by forming teams of heterogeneous robots. This work addresses the power limitations associated with individual robots, which have finite amounts of power, and thus limited operational lifetimes. This work presents a method by which mobile docking stations can optimize their locations in order to maximize the power available to the deployed robots. Simulated results are presented in which teams of docking stations continuously recover and recharge a much larger team of deployed robots. It is assumed that the deployed robots are able to maintain a communication link between themselves and the docking station. This communication link is used to provide position information and available power to the docking stations. The communication link may be direct from the robot to docking station or it may require the use of ad hoc routing through other deployed robots

Heterogeneous implementation of an adaptive robotic sensing team

When designing a mobile robotic team, an engineer is faced with many design choices. This paper discusses the design of a team consisting of two different models of robots with significantly different sensing and control capabilities intended to accomplish a similar task. Two new robotic platforms, the COTS Scout and the MegaScout are described along with their respective design considerations.

Mobile camera positioning to optimize the observability of human activity recognition tasks

The performance of systems for human activity recognition depends heavily on the placement of cameras observing the scene. This work addresses the question of the optimal placement of cameras to maximize the performance of these types of recognition tasks. Specifically, our goal is to optimize the quality of the joint observability of the tasks being performed by the subjects in an area. We develop a general analytical formulation of the observation problem, in terms of the statistics of the motion in the scene and the total resolution of the observed actions that is applicable to many observation tasks and multi-camera systems. A nonlinear optimization approach is used to find the internal and external (mounting position and orientation) camera parameters that optimize the recognition criteria. In these experiments, a single camera is repositioned using a mobile robot. Initial results for the problem of human activity recognition are presented.

Increasing the Scout's effectiveness through local sensing and ruggedization

The Scout is a miniature robot capable of performing surveillance and reconnaissance applications. However, the small size of the Scout limits the on-board processing capability and thus requires that the primary sensing modality (vision) be processed remotely. This creates a dependence upon a video channel which can become a severe bottleneck when attempting to use large numbers of robots. This paper discusses the newest generation of the Scout, the COTS 3.0, which attempts to reduce the effect of the communication bottleneck by using more local sensing capabilities to achieve a degree of autonomous functionality. Several experiments showing the durability of the new COTS Scout and the autonomous capability are presented.