This is a Work in Progress Research to Practice Category paper. Research has shown that novice programmers struggle with learning introductory concepts and find it difficult to monitor their own progress. Teachers often have hundreds of students and multiple sections of programming courses to teach, making it infeasible to provide the amount of independent feedback each student may need to flourish. With limited instructor feedback, students who can self-monitor and self-assess their programming metacognition have a higher chance of developing a process for solving programming challenges. In this paper, we expand on the literate programming paradigm by using natural language processing and machine learning methods to automatically analyze and classify student programming metacognition levels through their source code comments. Our intent is to ultimately integrate our classification models into an interactive developer environment to provide real-time feedback to students about their metacognition while learning to program.

Learning to program is a complex task and is a documented persistent challenge. We are intermingling Writing-to-Learn (WTL) strategies in support of learning to program. Initial efforts examined existing writing in the form of guided source code comments. This poster displays the results for the following three research questions: RQ1) What do source code comments tell us about novice programmers' thinking processes while coding? RQ2) What do source code comments tell us about how students visually organize their source code? RQ3) What differences exists for students receiving traditional instruction versus WTL instruction? To answer these questions, we analyzed students' programming assignments from an introductory programming course with and without WTL instruction. The analysis generated a qualitative codebook that can be used to classify source code comments with respect to thinking processes and organizational patterns. The resultant qualitative codebook is displayed and audience members can use the codebook to classify comments. We are soliciting feedback regarding the reliability, validity, and completeness of the codebook, and future project plans. This material is based upon work supported by the National Science Foundation under Grant No. DUE-1612132. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.

Continuum robots made from telescoping precurved elastic tubes enable base-mounted actuators to specify the curved shapes of robots as thin as standard surgical needles. While free space beam mechanics-based models of the shape of these `active cannulas' exist, current models cannot account for external forces and torques applied to the cannula by the environment. In this paper we apply geometrically exact beam theory to solve the statics problem for concentric-tube continuum robots. This yields the equivalent of forward kinematics for an active cannula with general tube precurvature functions and arbitrarily many tubes, under loading from a general wrench distribution. The model achieves average experimental tip errors of less than 3 mm over the workspace of a prototype active cannula subject to various tip forces.

Continuum robots, which are composed of multiple concentric, precurved elastic tubes, can provide dexterity at diameters equivalent to standard surgical needles. Recent mechanics-based models of these "active cannulas" are able to accurately describe the curve of the robot in free space, given the preformed tube curves and the linear and angular positions of the tube bases. However, in practical applications, where the active cannula must interact with its environment or apply controlled forces, a model that accounts for deformation under external loading is required. In this paper, we apply geometrically exact rod theory to produce a forward kinematic model that accurately describes large deflections due to a general collection of externally applied point and/or distributed wrench loads. This model accommodates arbitrarily many tubes, with each having a general preshaped curve. It also describes the independent torsional deformation of the individual tubes. Experimental results are provided for both point and distributed loads. Average tip error under load was 2.91 mm (1.5%-3% of total robot length), which is similar to the accuracy of existing free-space models.

This paper introduces a method for computing the shape of a continuously-flexible (continuum) robot in 3-D space which includes gravity loading by applying Cosserat rod theory to a continuum robot. With this theory, the shape of the rod can be determined using force-torque balance equations obtained from a simple free body diagram that represents the continuum robot. Real-time performance of 125 Hz makes this approach viable for the control of a continuum robot, enabled by avoiding boundary-value conditions in the solution.

We present a new geometrical approach to solving inverse kinematics for continuous backbone (continuum) robot manipulators. First, this paper presents a solution to the inverse kinematics problem for a single-section trunk. Assuming end-points for all sections of a multi-section trunk are known, this paper then details applying single-section inverse kinematics to each section of the multi-section trunk by compensating for resulting changes in orientation. Finally, an approach which computes per-section endpoints given only a final-section endpoint provides a complete solution to the multi-section inverse kinematics problem. The results of implementing these algorithms in simulation and on a physical continuum robot are presented and possible applications are discussed.

Continuum robotic manipulators, termed trunks, mimic the astounding capabilities of elephant trunks and octopus arms by bending in smooth arcs. Several approaches to kinematic analysis of continuum trunks complement a wide variety of available continuum robots. However, these kinematics exhibit singularity-like conditions when the trunk assumes a straight posture, which is essential to complete many tasks. The novel limiting-case analysis presented in this paper eliminates these problems, demonstrating that the unique causes of the problem are rooted in the continuum formulation and cannot be solved by traditional rigid-link singularity analysis. Three practical examples demonstrate the necessity of this analysis presented, enabling the trunk to successfully perform each task.

This paper proposes a novel approach in the design, construction and analysis of a continuum robot. The paper examines the drawbacks of two existing designs and proposes a new mechanical design that uses a single latex rubber tube as the central member, providing a design that is both simple and robust. Next, a new, simplified method of modeling kinematics is introduced. A novel verification procedure is then applied to examine the validity of the proposed model in two different domains of applicability and could be used to verify many other models that are constructed based on similar assumptions. Finally, a two-level electrical control scheme enables rapid prototyping.

Summary form only given. Continuum robots are biologically-inspired by the invertebrate organisms such as octopus arms and elephant trunks. These robots with a backbone-less structure offer a superior performance in unstructured and cluttered environments such as collapsed buildings, unknown geographical terrain, holes and tunnels. This video features OctArm, a continuum robot that demonstrates its capabilities in whole arm manipulation, biologically-inspired maneuvering, and grasping. The video also depicts a 3D graphical model of OctArm in that can be rendered in real-time in Matlab's real-time workshop.

This paper introduces new analyses and algorithms which are essential for the practical implementation of continuous backbone continuum robots. Actuator length limits strongly shape the configuration or joint space of continuum manipulators, introducing couplings which are not reflected in previously published kinematic models. These unmodeled effects significantly restrict the practical application of previously established kinematic models on continuum robot hardware. This paper presents a new analysis of the effects of actuator limits on continuum robots. Based on the new understanding of the configuration space uncovered, we derive for the first time the configuration space of continuum robots when constrained by actuator length limits. These contributions are essential for effective use of a wide range of continuum robots and have been implemented and tested on two different types of continuum robots. Results and insight gained from this implementation are presented

This paper describes the results of field trials and associated testing of the OctArm series of multi-section continuous backbone "continuum" robots. This novel series of manipulators has recently (Spring 2005) undergone a series of trials including open-air and in-water field tests. Outcomes of the trials, in which the manipulators demonstrated the ability for adaptive and novel manipulation in challenging environments, are described. Implications for the deployment of continuum robots in a variety of applications are discussed

In contrast to traditional robotic manipulators composed of rigid links, a continuum manipulator is a long, continuously flexible extremity that grasps objects usingthe entire length of the trunk. OctArm, a three-section continuum manipulator composed of 9 McKibben actuators, was mounted on tracked mobile platform and teleoperated in a series of field and laboratory experiments. Results from these experiments show its ability to grasp objects of many shapes and sizes, retain a solid hold despite vibration or changes in acceleration, cradle fragile objects reliably, and operate in extreme environments. This robust featureset shows the usefulness and strong potential of these manipulators.

Though a large number continuum robots exist, little work has been done to accurately and effectively visualize these devices in three dimensions. Like octopus arms and elephant trunks, these robots lack discrete joints, instead bending in smooth, continuous curves. Three-dimensional visualization of traditional rigid-link robots is both well established and extensively used in modeling, simulation, design, and operation of these robots. Providing three-dimensional visualization techniques extends these benefits, considered essential for rigid-link robots, to continuum robots. This paper presents a highly flexible three-dimensional visualization technique which executes in realtime for a large class of continuum robots. The results of this technique are then applied to two different continuum manipulators which are representative of most continuum robot designs, demonstrating the wide applicability of this method

This paper introduces three algorithms which are essential for the practical, real-time implementation of continuum robots. Continuum robots lack the joints and links which compose traditional and high-degree-of-freedom robots, instead relying on finite actuation mechanisms to shape the robot into a smooth curve. Actuator length limits shape the configuration or joint space of continuum manipulators, introducing couplings analyzed in this paper which must be understood to make effective use of continuum robot hardware. Based on the new understanding of the configuration space uncovered, this paper then derives the workspace of continuum robots when constrained by actuator length limits. Finally, a tangle/untangle algorithm correctly computes the shape of the distal segments of multisection tendon-actuated continuum robots. These contributions are essential for effective use of a wide range of continuum robots, and have been implemented and tested on two different types of continuum robots. Results and insight gained from this implementation are presented

We introduce a new method for synthesizing kinematic relationships for a general class of continuous backbone, or continuum , robots. The resulting kinematics enable real-time task and shape control by relating workspace (Cartesian) coordinates to actuator inputs, such as tendon lengths or pneumatic pressures, via robot shape coordinates. This novel approach, which carefully considers physical manipulator constraints, avoids artifacts of simplifying assumptions associated with previous approaches, such as the need to fit the resulting solutions to the physical robot. It is applicable to a wide class of existing continuum robots and models extension, as well as bending, of individual sections. In addition, this approach produces correct results for orientation, in contrast to some previously published approaches. Results of real-time implementations on two types of spatial multisection continuum manipulators are reported.

We introduce a new method for synthesizing kinematics and Jacobian relationships for an important class of continuous backbone “continuum” robots. The resulting Jacobians enable task and shape control by relating work space (Cartesian) coordinates to actuator inputs (tendon lengths, pneumatic pressures, etc.), via robot shape coordinates. The approach, which is applicable to a wide class of existing continuum robots, also features the capability of including extension, as well as bending, of individual sections. The approach is also shown to produce correct results for orientation, in contrast to previously published approaches. Results of a real-time implementation of the method on a multisection continuum manipulator are reported.

This paper presents new results for intuitive teleoperation of continuous backbone "continuum" robot manipulators. Continuum robots present unique challenges due to the nonintuitive (to humans) nature of their basic movements. We present a series of mappings, at both position and velocity levels, which provide human operators with a versatile and intuitive suite of options for joystick control of continuum robots. Results from implementations on two types of continuum manipulator hardware are summarized.

In this paper, we describe the design and implementation of a novel multi-section, continuous-backbone ("continuum") robot. The design is based on an innovative "hose-in-hose" concept. Its implementation is novel with respect to previous continuum robot designs in that stiffness and extension, in addition to bending, are actively controlled in each section of the robot. This requires a non-trivial extension of previously proposed kinematic models, and poses challenges for real-time control of the robot. We introduce a tangling/untangling algorithm to map between overall cable lengths and per-section cable lengths. Details of the design and its implementation are presented, along with a summary of real-time control issues and experimental results.