This work in progress research paper explores the ways that team-based design-build-compete projects may build engineering identity and a sense of belonging during the first year of an undergraduate engineering program. We analyzed end of semester retrospective interviews of students to identify instances of the quantity and quality of interaction criteria for developing a sense of belonging and the performance and recognition factors for developing engineering identity. Early findings suggest that the design project provides opportunities to develop both identity and sense of belonging. Additionally, a sense of belonging may have helped students to buffer negative performance and recognition to reframe the project as a positive team experience.

In this workshop, we introduce participants to vocabulary and theory to understand their students' affective experiences of doing engineering work. As attention to emotions and other affective elements of engineering student experiences has grown in the literature, this workshop will aid instructors in considering the importance of attitudes, emotions, and values/beliefs for student learning and identity development. The workshop will provide ample opportunity for discussion and reflection, and will empower instructors both to consider scaffolding of assignments with affect in mind and to survey students about their affective experiences in order to iterate on assignment design.

Soft fluidic actuators are becoming popular for their backdrivability, potential for high power density, and their support for power supply through flexible tubes. Control and design of such actuators requires serviceable models that describe how they relate fluid pressure and flow to mechanical force and motion. We present a simple 2-port model of a bellows actuator that accounts for the relationships among fluid and mechanical variables imposed by the kinematics of the deforming bellows structure and accounts for elastic energy stored in the actuator's thermoplastic material structure. Elastic energy storage due to axial deformation is captured by revolving a differential strip whose linear elastic behavior is a nonlinear function of the actuator length. The model is evaluated through experiments in which either actuator length and pressure or force and pressure are imposed. The model has an error of 9.8% of the force range explored and yields insight into the effects of geometry changes. The resulting model can be used for model-based control or actuator design across the full operating range and can be exercised under either imposed force or imposed actuator length.

This full research-to-practice paper is a collaboration between researchers and instructors to examine the scaffolding of open-ended problems. Most assigned homework problems are closed-ended with one correct answer and are unlike the ill-defined problems practicing engineers solve in the workplace. To begin bridging this gap, our research team of engineering education researchers and instructors have been designing and implementing ill-defined, open-ended homework problems for the past three years. This study presents instructor reflections on considerations for scaffolding open-ended problems, made after examining survey data from their own students. We present the results in six practices of scaffolding that better support students in their solving of the problems.

This full research paper examines students' epistemic affect, or their feelings about and within the doing of engineering, when encountering ill-defined problems in two of their first engineering science courses. Ill-defined problems are what students will encounter as professional engineers, but engineering students typically get little practice in their coursework at solving these types of problems. As students explained how they worked their way through the ill-defined and open-ended problems, we found evidence of both positive and negative feelings that arose, as well as descriptions of affective transitions, or shifts from one affect to another. Some of these transitions show evidence that students begin to regulate or anticipate these feelings as a result of repeated exposure to ill-defined problems. This work has implications for including the development of epistemic regulation as part of engineering students’ preparation for professional practice.

Passive transmission-based robotic devices are capable of providing motion guidance while ensuring user safety and engagement. To circumvent some of the drawbacks associated with steering continuously variable transmissions based on rolling contacts, we are exploring a class of discretely variable devices, based on brakes and hydrostatic transmissions. Previously available control methods for discretely variable devices were built on velocity fields and only developed to stabilize a one-dimensional (1-D) target manifold. For n-DOF devices, methods to stabilize target manifolds of dimensions 1 to n-1 are of interest. In this article, we contribute constraint field methods that stabilize n$-$1 dimensional target manifolds while leaving the orthogonal subspace free to the control of the operator. We also contribute force-modulated single degree of freedom (DOF) velocity fields, which add between 1 and n-2 virtual DOFs to the motion of devices whose physical constraints leave one DOF. Control performance is demonstrated in simulation for 3-DOF devices capable of imposing 1-D or 2-D constraints and in experiment for 2-DOF devices imposing 1-D constraints. Our experimental apparatus features digital hydraulic transmissions that are easily configured for an n-dimensional space and capable of imposing constraints of any dimension, thus motivating the contributed methods.

In this paper, we develop theoretical foundations for a new class of rehabilitation robot: body powered devices that route power between a user's joints. By harvesting power from a healthy joint to assist an impaired joint, novel bimanual and self-assist therapies are enabled. This approach complements existing robotic therapies aimed at promoting recovery of motor function after neurological injury. We employ hydraulic transmissions for routing power, or equivalently for coupling the motions of a user's joints. Fluid power routed through flexible tubing imposes constraints within a limb or between homologous joints across the body. Variable transmissions allow constraints to be steered on the fly, and simple valve switching realizes free space and locked motion. We examine two methods for realizing variable hydraulic transmissions: using valves to switch among redundant cylinders (digital hydraulics) or using an intervening electromechanical link. For both methods, we present a rigorous mathematical framework for describing and controlling the resulting constraints. Theoretical developments are supported by experiments using a prototype fluid-power exoskeleton.

The use of haptic display to refer cues sensed electronically from a prosthetic terminal device promises to improve the function of myoelectrically controlled upper limb prostheses. This promise is often evaluated in experiments involving non-amputees, though the availability of additional haptic feedback from an intact hand (auxiliary feedback) may confound attempts to use non-amputees as stand-ins for amputees. In this paper we test the influence of auxiliary haptic feedback on myoelectric control performance by introducing various grasp conditions in a compensatory tracking task. We ask non-amputees to compensate for the motion of a random signal by producing myoelectric control signals with a hard object, soft object, or no object (requiring co-contraction) in their grasp. The error signal is displayed through a squeeze band worn about the upper arm or a visual display. Our results suggest that the main difference between tracking with haptic and visual feedback is low-frequency drift, and that auxiliary feedback does not substantially influence task performance. Despite the drift, our results show that participants are able to respond to cues presented through the squeeze band in the compensatory tracking task.