Roy Godzdanker

ISLANDS: A Self-Leveling landing platform for autonomous miniature UAVs

The Intelligent Self-Leveling and Nodal Docking System (ISLANDS) is a mobile recharging/refueling station designed and built to enhance endurance and range of small-scale, autonomous, unmanned helicopters, which are becoming increasingly popular for a wide range of non-military applications such as, surveillance, reconnaissance, traffic monitoring, emergency response, agricultural spraying, and many other “eye in the sky” missions. The primary function of ISLANDS is to provide a safe, level landing platform for such helicopters. Additionally, in order to provide the maximum benefit in terms of increased range and flight-time, ISLANDS must be strategically located in the work field of the helicopter. In this paper, we discuss both the design of the individual ISLANDS “node,” and the use of ISLANDS within a larger systems context. At the node level, the mechanical subsystems implementing these ISLANDS are described. At the system level, we report on initial results tackling the ISLANDS placement problem with a genetic search algorithm. In combination, these contributions provide a complete solution to enable longer and more complex missions for small autonomous helicopters.

Side-Slipping Locomotion of a Miniature, Reconfigurable Limb/Tread Hybrid Robot

Holonomic behavior is desirable in the tight confines of a rubbled, collapsed-structure environment. But arbitrary motion is difficult to achieve, mechanically, particularly since treads are the most common form of locomotive device in search and rescue robots. We are developing a reconfigurable suite of locomotive modules that permit side-slipping locomotion. Initially designed as add-on modules to the TerminatorBot limbed crawler to create limb/tread hybrid robots, the modules can also be assembled with one another to produce holonomic differential drive robots, as well. This paper describes the design of a transverse tread module with unique buckling grousers that creates a tread/limb hybrid robot capable of both forward locomotion and transverse locomotion. Also described is a two-dimensional tread module that provides motive force in both the longitudinal and transverse directions. Two of these modules together in a differential drive configuration provides true holonomic capability. The addition of articulated linkages between modules provides holonomic serpentine behavior.

Improving endurance of autonomous aerial vehicles through intelligent service-station placement

A limitation of small-scale, autonomous, vertical take-off and landing (VTOL) vehicles is their relatively short flight time. This hinders their broad applicability for many commercial applications. In previous work, we present the design and implementation of ISLANDS, an autonomous self-leveling landing platform for VTOL vehicles, along with an initial approach to their placement in the field of work. In this paper, we present several new approaches for improved station placement in a field of work of arbitrary shape and size, given sensor characteristics and the nature of the application. We present these algorithms in the context of a generic survey application, but they generalize to many other applications such as search and rescue, traffic monitoring, and environment monitoring.

Auxiliary Motive Power for TerminatorBot: An Actuator Toolbox

A motive toolbox of reconfigurable modules is described to extend capabilities of the TerminatorBot. The robot can be statically reconfigured with both sensors and actuators for particular applications by way of the morphing bus. The morphing bus is a parallel bus that adapts to the modules connected. A software tool is provided to aid the user in static configuration. This paper focuses on three modules, still in the prototyping stage, for adding bulk motive force to the robot in a hybrid fashion. Methods of channeling the motive force are also discussed.

Evolving gaits for increased discriminability in terrain classification

Limbs are an attractive approach to certain niche robotic applications, such as urban search and rescue, that require both small size and the ability to locomote through highly rubbled terrain. Unfortunately, a large number of degrees of freedom implies there is a large space of non- optimal locomotion trajectories (gaits), making gait adaptation critical. On the other hand, these extra degrees of freedom open many possibilities for active sensing of the terrain, which is essential information for adapting the gait. In previous work, we developed a metric for terrain classification that makes use of the loping body motion (i.e. gait bounce) during locomotion. In this work we present a framework for evolving gaits to better differentiate the gait bounce signal across terrains. This framework includes a limb/terrain interaction model that estimates gait bounce based on established models of wheel/terrain interaction, and an objective function that can be optimized for terrain discriminability. Additional objective functions for improved locomotion are presented, as well as culling agents that help guide the evolution process away from real-world impossibilities.

Development and User Testing of the Gestural Joystick for Gloves-On Hazardous Environments

For controlling robots in an urban search and rescue (USAR) application, a wearable joystick is presented with improved sensing capability as well as a giant magneto-resistance (GMR) sensor model for use with rare-earth magnets. Scientists have been studying a variety of existing human/robot interface devices to control USAR robots in a disaster. Due to the stresses involved in USAR environments, the selection of an appropriate interface device out of the numerous interactive devices available has to be carefully considered. Furthermore, the total burden to the user of human/robot interface devices in USAR tasks includes not only the periods of interaction, but also the burden of transporting and remotely setting up the devices. The wearable joystick presented is developed with the design goal of minimizing total encumbrances. The features of this wearable joystick include easy and wire-free installation into regular gloves. An improved hardware structure for the sensor pad and the alignment of magnets is described that completely wraps the wrist. This band-type mechanism provides more robust data acquisition than previous prototypes. To evaluate performance, time-to-complete tests are performed, with a comparison to a metric for path tortuosity. The fractal dimension of the resulting path is analyzed to represent the degree of control the user has over the interface device. Experimental results are provided from both computer screen tess and real USAR robot driving tests.

Reconfigurable robots with Heterogeneous Drive Mechanisms: The kinematics of the Heterogeneous Differential Drive

Statically and dynamically reconfigurable robot mechanisms have been extensively studied by a number of researchers. Control formulations have been proposed for specific mechanisms and some researchers have tried to build unified frameworks for general robot control. This paper reports an extension of the differential drive mechanism that we call the Heterogeneous Differential Drive. Bridging the gap between differential drive mechanisms and skid-steered mechanisms, the heterogeneous differential drive permits the modular combination of different types of actuators with different capabilities under one unified framework. It is a step toward a unified framework for actuators we call Heterogeneous Drive Mechanisms that permits reconfigurable mechanisms with homogeneous or heterogeneous components. The heterogeneous differential drive is a theoretical class of vehicles that lies in the gray area between pure differential drive vehicles and pure skid steered vehicles, yet represents either at the extremes. The heterogeneous differential drive also provides the basis for our preliminary development of the heterogeneous drive. This paper develops the kinematic model of the heterogeneous differential drive from the kinematic model of the differential drive formulation and describes an example mechanism.

Non-isomorphic tread design for a side-slipping tread/limb hybrid robot

A novel tread design is described for the crawling robot TerminatorBot that allows side-slipping locomotion. This module creates a tread/limb hybrid robot capable of both forward locomotion and transverse locomotion. This paper focuses on the preliminary analysis of the rubber cantilever beams that result in nonisotropic behavior of the tread which we hope will allow enhanced capability in both forward and sideways motion.

Steering Control of an Active Tether Through Mass Matrix Control

The smaller the robot the easier it is for it to access voids in a collapsed structure. Yet, small size brings a host of problems due to resource constraints. One of the primary constraints on small robots is limited motive power to surmount obstacles and rough terrain. We are developing a small reconfigurable robotic system with various add-on modules to provide bulk motive force adaptable for different scenarios. The difficulty in adding modules with unsteerable motive force to generic host robots stems from directing the energy in the proper direction in a general way. This paper investigates modulating the non-isotropic Cartesian mass matrix of a robot, in contact with the ground, to passively steer the acceleration resulting from a motive force module. A robot in contact with the ground in a statically stable configuration is a parallel chain mechanism. We dynamically model the robot itself as an augmented object supported by multiple serial chain mechanisms to ground. In this paper, we develop the Cartesian mass matrix of the TerminatorBot robot by summing the dynamics component of each individual serial chain using the operational space formulation. A map is built of the resulting Cartesian acceleration vectors as a function of the robots configuration. Desired acceleration vectors are mapped backwards from Cartesian space to configuration space, allowing the controller to assume a stance for the robot that will result in the desired motion.