Mark B. Colton

Trends and considerations in robot-assisted autism therapy

Recent research suggests that children with autism exhibit certain positive social behaviors while interacting with robots that are not observed while interacting with their peers, caregivers, and therapists. This paper explores trends in robot-assisted autism therapy, as well as some of the specific therapies that have been shown to elicit desirable social interactions when working with children with autism. Considerations for the design of robots for use in robot-assisted therapies are also presented. Finally, general conclusions and recommendations are made to help further the work of robot-assisted autism therapy.

The effects of head-mounted display mechanical properties and field of view on distance judgments in virtual environments

Research has shown that people are able to judge distances accurately in full-cue, real-world environments using visually directed actions. However, in virtual environments viewed with head-mounted display (HMD) systems, there is evidence that people act as though the virtual space is smaller than intended. This is a surprising result given how well people act in real environments. The behavior in the virtual setting may be linked to distortions in the available visual cues or to a persons ability to locomote without vision. Either could result from issues related to added mass, moments of inertia, and restricted field of view in HMDs. This article describes an experiment in which distance judgments based on normal real-world and HMD viewing are compared with judgments based on real-world viewing while wearing two specialized devices. One is a mock HMD, which replicated the mass, moments of inertia, and field of view of the HMD and the other an inertial headband designed to replicate the mass and moments of inertia of the HMD, but constructed to not restrict the field of view of the observer or otherwise feel like wearing a helmet. Distance judgments using the mock HMD showed a statistically significant underestimation relative to the no restriction condition but not of a magnitude sufficient to account for all the distance compression seen in the HMD. Indicated distances with the inertial headband were not significantly smaller than those made with no restrictions.

The effects of head-mounted display mechanics on distance judgments in virtual environments

In virtual environments that use head-mounted displays (HMD), distance judgments to targets on the ground are compressed, at least when indicated through visually-directed walking tasks. The same tasks performed in the real world yield veridical results over distances ranging from 2m to 25m. This paper describes experiments aimed at determining if mechanical aspects of HMDs such as mass and moments of inertia are responsible for the apparent distortion of distance. Our results indicate that the mechanical aspects of HMDs cannot explain the full magnitude of distance underestimation seen in HMD-based virtual environments, though they may account for a portion of the effect.

Detailed requirements for robots in autism therapy

Robot-based autism therapy is a rapidly developing area of research, with a wide variety of robots being developed for use in clinical settings. Specific, detailed requirements for robots and user interfaces are needed to provide guidelines for the creation of robots that more effectively assist therapists in autism therapy. This paper enumerates a set of requirements for a clinical humanoid robot and the associated human interface. The design of two humanoid robots and an intuitive and flexible user interface for use by therapists in the treatment of children with autism is described.

Haptic collision avoidance for a remotely operated quadrotor UAV in indoor environments

Quadrotors are well-suited for indoor flight because of their ability to hover and maneuver in confined spaces. However, remote operation of these vehicles is challenging because of the loss sensory perception. This paper presents methods for using force feedback exerted by the command input device on the hand of the pilot to assist in avoiding collisions while navigating in a 3D indoor environment. Three algorithms for calculating the feedback forces are presented and tested in simulation-based user studies. The force feedback and control system is demonstrated by piloting a physical quadrotor in an indoor environment.

Identification of nonlinear passive devices for haptic simulations

This paper describes a method for identifying models of a class of nonlinear passive devices, such as switches, knobs, and buttons. A general nonlinear impedance model is presented, which accounts for dynamics that change with both position and direction. Exponentially-weighted least-squares is used to fit the nonlinear model to experimental data from a specially designed physical 1-DOF test device with inherent nonlinearities. The data are obtained using an instrumented linear probe.

Reality-Based Haptic Force Models of Buttons and Switches

Accurate models of the feel of physical objects are essential to improving the realism of haptic simulations. This paper presents a method for automatically obtaining experimentally based models of general passive, nonlinear devices for use in haptic playback applications, with specific emphasis on modeling switches and buttons. The method, based on the exponentially weighted least-squares (EWLS), allows estimation of position- and direction-dependent parameters of a general nonlinear model. Results are presented for two push-button switches.

A Differentially Driven Flapping Wing Mechanism for Force Analysis and Trajectory Optimization

Flapping flight has the potential to revolutionize micro air vehicles (MAVs) due to increased aerodynamic performance, improved maneuverability, and hover capabilities. This paper presents the design of a robotic flapping wing mechanism for use in general studies involving flapping flight and laboratory-based experimental optimization of flapping trajectories. The design allows for dynamic adjustment of flapping trajectories in air or liquids with three rotational degrees of freedom on each wing. The design, instrumentation, and control of the mechanism are discussed, and experimental characterization of the mechanisms performance is presented. Preliminary trajectory optimization using a Box-Behnken design approach is used and shows successful parameter optimization. The limitations of the current mechanism are addressed. A survey of flapping mechanisms is presented.

Multi-vehicle dynamics and control for aerial recovery of micro air vehicles

This paper presents a method for recovering Micro Air Vehicles (MAVs) in flight using a mothership and towed drogue. A method for modelling the dynamics of the mothership-cable-drogue system, based on Gausss principle, is presented. The differential flatness property of the system is exploited to calculate mothership trajectories from desired drogue orbits, and a Lyapunov based controller is proposed that enables accurate mothership trajectory tracking. A drag-based controller for the drogue is also described. Methods to enable the MAV to estimate and track the drogue orbit are discussed. The modelling and control methods are illustrated through simulation and flight results.

Toys in the Classroom: LEGO MindStorms as an Educational Haptics Platform

Haptics has the potential to be: a powerful tool in science and engineering education of college and pre-college students. This paper proposes teaching engineering and programming concepts using haptic interfaces created with LEGO MindStorms, a popular system for developing robotic devices. A general overview of the MindStorms system is presented, followed by the results of experiments that characterize the performance of the MindStorms components and establish the suitability of MindStorms for constructing haptic interfaces. Two prototype haptic interfaces are created and interfaced with a PC-based graphics display. Initial results show that MindStorms provides an excellent platform for designing, constructing, programming, and interfacing simple haptic devices,. Potential uses in college and pre-college curricula are discussed.