The function of the engineering profession is to manipulate materials, energy, and information, thereby creating benefit for humankind. To do this successfully, engineers must have a knowledge of nature that goes beyond mere theory—knowledge that is traditionally gained in educational laboratories. Over the years, however, the nature of these laboratories has changed. This paper describes the history of some of these changes and explores in some depth a few of the major factors influencing laboratories today. In particular, the paper considers the lack of coherent learning objectives for laboratories and how this lack has limited the effectiveness of laboratories and hampered meaningful research in the area. A list of fundamental objectives is presented along with suggestions for possible future research.

http://web.stanford.edu/group/asee/wikiupload/6/69/Feisel_LabsInEngEd.pdf

The Role of the Laboratory in Undergraduate Engineering Education

The modeling of forces during needle insertion into soft tissue is important for accurate surgical simulation, preoperative planning, and intelligent robotic assistance for percutaneous therapies. We present a force model for needle insertion and experimental procedures for acquiring data from ex vivo tissue to populate that model. Data were collected from bovine livers using a one-degree-of-freedom robot equipped with a load cell and needle attachment. computed tomography imaging was used to segment the needle insertion process into phases identifying different relative velocities between the needle and tissue. The data were measured and modeled in three parts: 1) capsule stiffness, a nonlinear spring model; 2) friction, a modified Karnopp model; and 3) cutting, a constant for a given tissue. In addition, we characterized the effects of needle diameter and tip type on insertion force using a silicone rubber phantom. In comparison to triangular and diamond tips, a bevel tip causes more needle bending and is more easily affected by tissue density variations. Forces for larger diameter needles are higher due to increased cutting and friction forces.

Force modeling for needle insertion into soft tissue

Friction force models play a fundamental role for simulation of mechanical systems. Their choice affects the matching of numerical results with physically observed behavior. Friction is a complex phenomenon depending on many physical parameters and working conditions, and none of the available models can claim general validity. This paper focuses the attention on well-known friction models and offers a review and comparison based on numerical efficiency. However, it should be acknowledged that each model has its own distinctive pros and cons. Suitability of the model depends on physical and operating conditions. Features such as the capability to replicate stiction, Stribeck effect, and pre-sliding displacement are taken into account when selecting a friction formulation. For mechanical systems, the computational efficiency of the algorithm is a critical issue when a fast and responsive dynamic computation is required. This paper reports and compares eight widespread engineering friction force models. These are divided into two main categories: those based on the Coulomb approach and those established on the bristle analogy. The numerical performances and differences of each model have been monitored and compared. Three test cases are discussed: the Rabinowicz test and other two test problems casted for this occurrence.

Review and comparison of dry friction force models

As human beings, we can interact with our environment through the sense of touch, which helps us to build an understanding of objects and events. The implications of touch for cognition are recognized by many educators who advocate the use of “hands-on” instruction. But is it possible to know something more completely by touching it? Does touch promote the construction of more connected and meaningful understandings? Current technology makes the addition of touch to computer-generated environments possible, but the educational implications of this innovation are still largely unknown. This article is a baseline review that examines the role of touch in cognition and learning and explores the research investigating the efficacy of the haptic augmentation of instruction.

Haptics in Education: Exploring an Untapped Sensory Modality

Vibrations can significantly enhance touch perception for virtual environment applications with minimal design complexity and cost. In order to create realistic vibrotactile feedback, we collected vibrations, forces, and velocities during various tasks executed with a stylus: tapping on materials, stroking textures, and puncturing membranes. Empirical models were fit to these waveforms and a library of model parameters was compiled. These models simulated tasks involving simultaneous display of forces and vibrations on a high-bandwidth force-feedback joystick. Vibration feedback adds little complexity to virtual environment algorithms. Human subjects interacting with the system showed improved execution and perception when performing surface feature discrimination tasks.

/pdf/vibration-feedback-models-for-virtual-environments-2gt29k6tcy.pdf

Vibration feedback models for virtual environments

As an innovative approach to providing physical demonstrations in the engineering classroom, we present the haptic paddle: a low-cost, single-axis force-feedback joystick. Using the paddle in the laboratory component of an undergraduate course on dynamic systems, students not only learned to model and analyze dynamic systems, but they also felt the effects of phenomena such as viscous damping, stiffness, and inertia. By interacting with virtual environments using their sense of touch, students improved their understanding of dynamic systems, modeling and control. In addition, the paddles added entertainment and excitement to the course. In this paper, we describe the purpose and design of the haptic paddle, show examples of how the paddle was integrated into the course, and present the results of preliminary student evaluations.

Feeling Is Believing: Using A Force Feedback Joystick To Teach Dynamic Systems

/pdf/feeling-is-believing-using-a-force-feedback-joystick-to-1fyts0195f.pdf

Feeling is Believing: Using a Force‐Feedback Joystick to Teach Dynamic Systems

A method of identifying the friction of real devices for haptic display is presented. The method is suitable for identifying both the friction and inertia of a system simultaneously. This paper begins with a brief survey of common friction models and identification procedures. After the identification method is outlined, results are presented for experiments conducted to identify the friction and mass of an aluminum block sliding on sheets of brass, teflon, and rubber.

Friction Identification for Haptic Display

Low cost, single-axis force reflecting joysticks were used to teach students about electromechanical systems, dynamics and controls. The students assembled the devices from kits, tested and analyzed them, and used them to interact with computer models of dynamic systems. The devices helped students to appreciate such phenomena as equivalent inertia, friction and the effects of changing control system parameters. They also generated high enthusiasm among the students, particularly when used in cooperative “haptic video games” at the end of the course.

/pdf/getting-a-feel-for-dynamics-using-haptic-interface-kits-for-3w2ay64a6j.pdf

Getting a feel for dynamics: using haptic interface kits for teaching dynamics and controls

We review the state of the art in friction estimation and rendering for haptic interfaces and present a method based on a modified Karnopp friction model. We illustrate some of the advantages of this approach and show how it can be used to create accurate and convincing displays of sliding friction, including pre-sliding displacement and stick-slip behavior. We also present the results of human performance experiments in targeting tasks and show that real and simulated friction produce essentially the same results. In both cases, moderate low-stiction friction can improve performance and high stiction degrades it.

Christopher Richard

Papers

Feeling Is Believing: Using A Force Feedback Joystick To Teach Dynamic Systems

Feeling is Believing: Using a Force‐Feedback Joystick to Teach Dynamic Systems

Friction Identification for Haptic Display

Getting a feel for dynamics: using haptic interface kits for teaching dynamics and controls

Friction modeling and display in haptic applications involving user performance