Higher education has the opportunity (and often the mandate) to provide STEM outreach to their communities. Summer camp programs are one mechanism for providing quality CS learning experiences to a wide audience. This BOF will provide a platform for discussing strategies to make summer camps fun and sustainable. What are camp topics have been successful? How is funding obtained and sustained? Nationally, technology camps run the gamut from small, one-week programs to large camps that serve hundreds. The proposer will share his experience developing the University of Utah GREAT camps (www.cs.utah.edu/~dejohnso/GREAT), which have over 700 students attend one-week camps and hopes the BOF will attract others with their own experiences.

In this paper, we describe ITCH, an automatic testing system for projects in the Scratch programming language. While Scratch lacks traditional input/output mechanisms, ITCH overcomes this by exploiting the persistent saved project state to embed ITCH-specific lists that retain project output. In addition, the ITCH system replaces Scratch user input commands with automatically assigned test values. ITCH can gather variable state from running code, redirect output to a file, and capture drawings done by a Scratch project to save in a report format. The ITCH system has been successfully used in a large computer science explorations class where small practice code questions are assigned before extending work to larger, more creative projects without further burdening course graders. Examples of course projects and the ITCH-tested practice questions are given.

We investigate the role of contact location information on the perception of local features during contour following in a virtual environment. An absolute identification experiment is conducted under force-alone and force-plus-contact-location conditions to investigate the effect of the contact location information. The results show that the participants identify the local features significantly better in terms of higher information transfer for the force-plus-contact-location condition, while no significant difference was found for measures of the efficacy of contour following between the two conditions. Further data analyses indicate that the improved identification of local features with contact location information is due to the improved identification of small surface features.

A novel, low inertia, two degree-of-freedom (2-DOF) contact location display (CLD) device has been designed, prototyped, and tested. This device positions a small spherical contactor beneath the user's fingerpad at the point of contact between the finger and a virtual surface. Kinesthetic forces are provided by a custom haptic device attached to the CLD. The contactor is remotely driven by push-pull wires to reduce the effective inertia of the device at the user's fingertip; however, this design results in significant mechanical backlash. This backlash is characterized and partially compensated for in software. An experiment was used to evaluate several methods of rendering tactile feedback, each using a different method of prepositioning the contactor. The results show no statistical performance differences between rendering conditions. However, a post-experiment survey shows that participants perceived contact location + kinesthetic feedback as more realistic than pure kinesthetic feedback.

The effect of contact location information on the perception of virtual edges was investigated by comparing human edge sharpness discrimination under the force-alone and force-plus-contact-location conditions. The virtual object consisted of the 2D profile of an edge with two adjoining surfaces. Edge sharpness JNDs for both conditions increased from about 2 to 7 mm as the edge radii increased from 2.5 to 20.0 mm, and no significant difference was found between the two conditions. A follow-up experiment with the contact-location alone condition resulted in higher (worse) edge sharpness discrimination thresholds, especially at higher edge radius values. Our results suggest that contact location cues alone are capable of conveying edge sharpness information, but that force cues dominate edge sharpness perception when both types of cues are available.

Shape memory alloy (SMA) actuators are compact and have high force-to-weight ratios, making them strong candidates to actuate robots, exoskeletons, and prosthetics. To optimize speed and energy consumption, SMA actuators have been embedded in an NxN vascular network that can deliver electric and thermofluidic energy to the each actuator. The scalable architecture of the vascular network allows for 2N control devices (valves, transistors) to be shared amongst N2actuators, so that as the number of actuators increases, the number of required control devices scales at a smaller rate. This Network Array Architecture (NAA) allows for each actuator to be controlled individually or in discrete subarrays. However, not all combinations of actuators can be activated simultaneously; therefore in general, a sequence of control commands will be need to be executed in order to achieve the desired actuation. By treating each actuator as having a binary state, the combined states of the actuator array can be represented by graph theory, where states are nodes and the transitions between states are graph edges. By properly weighting the costs of the transitions, graph search techniques can be used to find optimal sets of control commands for desired state changes. This paper formulates the control of NAA actuators systems as a graph theory problem, and characterizes the ability of search algorithms to optimize a weighted combination of speed and energy usage, while minimizing computational cost.

Shape memory alloy (SMA) actuators are compact and have high force-to-weight ratios, making them strong candidates to actuate robots, exoskeletons, and prosthetics. However, these actuators are thermomechanical in nature and slow cooling rates can limit their performance. To improve the convective cooling, SMA wires have been embedded in vascular networks allowing cold fluid to pass across the actuators to cool/extend them. The vascular network can also deliver hot fluid to heat and contract the wire. In addition to the fluidic network, an electrical network operating in parallel can resistively heat the SMA to produce contraction. To minimize the weight and size of the vascular and electrical networks, a scalable N[N architecture has been implemented that allows for 2N control devices (valves, transistors) to be shared amongst N2actuators. This Network Array Architecture (NAA) allows each actuator to be controlled individually or in discrete subarrays. However, this architecture does not allow all combinations of actuators to be activated simultaneously; therefore in general a sequence of control commands will need to be executed in order to achieve the complete actuation. In order to find an optimal sequence of control commands, graph theory algorithms have been implemented. By treating each actuator's state as binary (fully contracted or extended), the collected states of an actuator array can be represented as nodes of the graph and the control commands as the graph edges. By properly weighting the costs of the graph edges, search algorithms can be used to find an optimal set of control commands for desired state changes. NAA results in a multi-graph that has 2NA—Nnodes and is highly interconnected. While initial work in this area established the basic validity of a graph search approach for NAA control, this article presents a scalable method of determining the optimal set of controls to minimize the operating cost (time and energy) and computational search cost.

We present an efficient and robust algorithm for computing the minimum distance between a point and freeform curve or surface by lifting the problem into a higher dimension. This higher dimensional formulation solves for all query points in the domain simultaneously, therefore providing opportunities to speed computation by applying coherency techniques. In this framework, minimum distance between a point and planar curve is solved using a single polynomial equation in three variables (two variables for a position of the point and one for the curve). This formulation yields two-manifold surfaces as a zero-set in a 3D parameter space. Given a particular query point, the solution space's remaining degrees-of-freedom are fixed and we can numerically compute the minimum distance in a very efficient way. We further recast the problem of analyzing the topological structure of the solution space to that of solving two polynomial equations in three variables. This topological information provides an elegant way to efficiently find a global minimum distance solution for spatially coherent queries. Additionally, we extend this approach to a 3D case. We formulate the problem for the surface case using two polynomial equations in five variables. The effectiveness of our approach is demonstrated with several experimental results.

This paper describes a haptic rendering algorithm for arbitrary polygonal models using a six degree-of-freedom haptic interface. The algorithm supports activities such as virtual prototyping of complex polygonal models and adding haptic interaction to virtual environments. The underlying collision system computes local extrema in distance between the model controlled by the haptic device and the rest of the scene. The haptic rendering computes forces and torques on the moving model based on these local extrema. The system is demonstrated on models with tens of thousands of triangles and developed in an accessibility application for finding collision-free paths.

Article Share on Spatialized normal come hierarchies Authors: David E. Johnson Univ. of Utah, Salt Lake City Univ. of Utah, Salt Lake CityView Profile , Elaine Cohen Univ. of Utah, Salt Lake City Univ. of Utah, Salt Lake CityView Profile Authors Info & Claims I3D '01: Proceedings of the 2001 symposium on Interactive 3D graphicsMarch 2001 Pages 129–134https://doi.org/10.1145/364338.364380Published:01 March 2001Publication History 27citation550DownloadsMetricsTotal Citations27Total Downloads550Last 12 Months13Last 6 weeks1 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteGet Access

Minimum distance computations on complex geometry commonly employ hierarchies of bounding volumes that are pruned through establishment of upper and lower bounds. In this paper we describe a novel time coherence scheme which utilizes coherence on these bounds, rather than coherence derived from the geometry of the bounding volumes or from the geometry of the underlying model. This method is thus independent of the bounding volume and model representations. In tests, we find using this approach can more than double the speed of a noncoherent approach.

We present a method for painting texture maps directly onto trimmed NURBS models using a haptic interface. The haptic interface enables an artist to use a natural painting style while creating a texture. It avoids the traditional difficulty of mapping between the 2D texture space and the 3D model space by using parametric information available from our haptic tracing algorithm. The system maps user movement in 3D to movement in the 2D texture space and adaptively resizes the paintbrush in texture space to create a uniform stroke on the model.

We present a framework for minimum distance computations that allows efficient solution of minimum distance queries on a variety of surface representations, including sculptured surfaces. The framework depends on geometric reasoning rather than numerical methods and can be implemented straightforwardly. We demonstrate performance that compares favorably to other polygonal methods and is faster than reported results for other methods on sculptured surfaces.

A haptic display system is presented for manipulating virtual mechanisms derived from a mechanical CAD design. Links are designed and assembled into mechanisms using Utah's Alpha-1 CAD system, and are then manipulated with a Sarcos Dextrous Arm Master. Based on the mechanism's kinematics and the virtual grasp, the motion of the master is divided into motion of the mechanism and constraint violation. The operator experiences the dynamic forces from the mechanism plus constraint forces.

A new tracing algorithm is described that supports haptic rendering of NURBS surfaces without the use of any intermediate representation. By using this tracing algorithm in conjunction with algorithms for surface proximity testing and surface transitions, a complete haptic rendering system for sculptured models has been developed. The system links an advanced CAD modeling system with a Sarcos force-reflecting exo-skeleton arm. A method for measuring the quality of the tracking component of the haptic rendering separately from the haptic device and force computation is also described.