Kemal Berk Yesin

Enlisting rangers and scouts for reconnaissance and surveillance

Reconnaissance and surveillance are important activities for both military and civilian organizations, for hostage and survivor rescue, drug raids, response to chemical or toxic waste spills etc. We have developed a distributed heterogeneous robotic team that is based mainly on a miniature robotic system. Because some operations require covert action, most of the robots are extremely small. This also allows them to be easily transported and allows for a greater number to be brought into use for a single operation. This makes them expendable without jeopardizing the overall mission. We call these small robots scouts. Their individual components must all be exceedingly small, and their overall design must make maximum use of all available space. They must make efficient use of resources (e.g., batteries). We meet these challenges with an innovative design and creative use of additional support. We team the scouts with larger ranger robots, which can transport the scouts over distances of several kilometers, deploy them rapidly over a large area, coordinate their behavior, and collect and present the resulting data. We present the scouts and rangers, discuss their capabilities along with the associated software, and describe demonstrations conducted to test the innovative aspects of the system. We also discuss related work, analyze our results, and draw conclusions.

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.

A CAD model based tracking system for visually guided microassembly

We present a visual feedback method for closed loop control of automated microassembly. A CAD model based multi-camera visual tracking system that is well suited for flexible automation and assembly of complex 3D geometries was developed. The system is capable of providing six degree-of-freedom pose feedback on the observed micro-components in real-time (30 Hz). Using CAD models of the observed objects, a complete description of the observed scene, including the effect of occlusions, is available and dependence on distinctive visual features such as fudicial marks is avoided.

Analysis and design of wireless magnetically guided microrobots in body fluids

The active guidance of magnetic particles inside biological organisms for drug delivery, cell separation, and protein manipulation has been actively pursued in biomedical research for many years. Recent advances in the integration of magnetic materials in MEMS are enabling the convergence of these two technologies towards the realization of wireless magnetically guided biomedical microrobots. This paper discusses some of the fundamental design issues for a biomedical microrobot that is actively steered in body fluids using magnetic fields. The effects of miniaturization on magnetic, fluid drag, and gravity/buoyancy forces and on control stability are analyzed. The advantages of using hard magnetic materials and the state of the art in the integration of hard magnetic materials into MEMS devices are discussed. The analysis indicates that untethered microrobots capable of being navigated under external control within biological organisms including the human body is a realistic goal.

Robust CAD model based visual tracking for 3D microassembly using image space potentials

A CAD model based visual tracking system for the flexible automation of 3D microassembly processes is presented. The system achieves six degrees-of-freedom tracking of MEMS components in real-time (30 Hz). The experimental results indicate a 1/spl sigma/ precision of 1.0 /spl mu/m and a positioning accuracy of 2%. A major source of errors in model based tracking is due to ambiguous object configurations with closely spaced edges. We also present a real-time image space potential method that utilizes the readily available model information to reduce these errors and improve tracking robustness.

Guidance of magnetic intraocular microrobots by active defocused tracking

Current laparoscopic techniques for intraocular surgery require that the vitreous humor is removed and at least three cannulas are inserted through the sidewalls of the eye. This paper investigates an alternate intraocular surgical technique based on the use of wireless microrobots guided by external magnetic fields. Issues investigated include the effects of magnetic and viscous drag forces faced by magnetic microrobots in the vitreous humor and the 3D visual servoing of these microrobots using a single microscope view. A new active defocused tracking method is proposed for visually servoing the microrobot along the optical axis of the microscope. This method uses a purposely defocused view of the microrobot to unambiguously resolve depth while servoing. Experimental results demonstrating the method with a microrobot visually servoed in 3D at 60 Hz using a single microscope view are presented.

Active video system for a miniature reconnaissance robot

In this paper we present an active video module that consists of a miniature video sensor, a wireless video transmitter and a pan-tilt mechanism driven by micromotors. The video module is part of a miniature mobile robot that is projected to areas of the environment to be surveyed. A single-chip CMOS video sensor and miniature brushless DC gearmotors are used to comply with restrictions imposed by the robotic system in terms of payload weight volume and power consumption. Different types of actuation are analyzed for compatibility with a mesoscale robotic system. Applications of an active video module are discussed.

Using orthogonal visual servoing errors for classifying terrain

A novel, centimeter-scale crawling robot has been developed to address applications in surveillance, search-and-rescue, and planetary exploration. This places constraints on size and durability that minimizes the mechanism. As a result, a dual-use design employing two arms for both manipulation and locomotion was conceived. In a complementary fashion, this paper investigates the dual-use of visual servoing error. Visual servoing can be used by a mobile robot for homing and tracking. But because ground-based mobile robots are inherently planar, the control methodology (steering) is one-dimensional. The two-dimensional nature of image-based servoing leaves additional information content to be used in other contexts. We explore this information in the context of classifying terrain conditions. An outline for gait adaptation based on this is suggested for future work.

Design of the UMN Multi-Robot System

Robotic reconnaissance and search and rescue are daunting tasks, especially in unknown and dynamic environments. The Scout is a robotic platform that is robust and flexible to operate in adverse and changing situations without revealing itself or disturbing the environment. The Scout can complete these missions by utilizing its small form factor for effective deployment, placement, and concealment while being equipped with a variety of sensors to accommodate different objectives. Unfortunately, the Scout has a limited volume to share among power, locomotion, sensors, and communications. Several novel approaches addressing deficiencies in specific tasks have been implemented in specialized Scouts and will be discussed in this paper. By building a diverse team of specialized Scouts, the team’s strengths outweigh an individual weakness.

System of launchable mesoscale robots for distributed sensing

A system of launchable miniature mobile robots with various sensors as payload is used for distributed sensing. The robots are projected to areas of interest either by a robot launcher or by a human operator using standard equipment. A wireless communication network is used to exchange information with the robots. Payloads such as a MEMS sensor for vibration detection, a microphone and an active video module are used mainly to detect humans. The video camera provides live images through a wireless video transmitter and a pan-tilt mechanism expands the effective field of view. There are strict restrictions on total volume and power consumption of the payloads due to the small size of the robot. Emerging technologies are used to address these restrictions. In this paper, we describe the use of microrobotic technologies to develop active vision modules for the mesoscale robot. A single chip CMOS video sensor is used along with a miniature lens that is approximately the size of a sugar cube. The device consumes 100 mW; about 5 times less than the power consumption of a comparable CCD camera. Miniature gearmotors 3 mm in diameter are used to drive the pan-tilt mechanism. A miniature video transmitter is used to transmit analog video signals from the camera.