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.

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.

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.

When a distributed robotic system is assigned to perform reconnaissance or surveillance, restrictions inherent to the design of an individual robot limit the system's 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 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.

Presents a miniature robotic system ("scout") useful for reconnaissance and surveillance missions. A large number of scout robots are deployed and controlled by humans and/or larger "ranger" robots. The specially designed and constructed scouts are extremely small (roughly 116cc volume) yet are readily deployable (by tossing or launching), have multiple mobility modes, have multiple sensing capabilities, can transmit and receive data and instructions, and have a limited capability for autonomous action. The rangers are significantly larger vehicles, based on a commercial-off-the-shelf platform, augmented with scout launchers, radios, and additional sensors. Together, the scouts and rangers form a hierarchical team capable of carrying out complex missions in a wide variety of environments.

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.