Haptic Paddle Design

Hands-on Haptics: Critical Infrastructure for Mechanical Engineering Curriculum Enhancement

NSF DUE-0411235

The primary goal of this Type 1 A&I program is to improve the effectiveness of laboratory exercises in a required undergraduate mechanical engineering course via student-centered learning and laboratory topics featuring integrated systems.  The specific objectives are:

• Improve cohesiveness of course and lab content and consequently, deepen student conceptual understanding of system dynamics concepts
• Demonstrate that haptic virtual learning increases student ability to apply conceptual knowledge to real-world systems
• Improve understanding of critical system dynamics topics in a cost-effective way

To reach these objectives, Rice has adopted laboratory exercises based around haptic interfaces (paddles), devices that allow users to interact via the sense of touch with virtual environments.  These multi-sensory (visual, haptic) labs are closely tied to course concepts and feature embedded assessment. 

The intellectual merit of the project is that students study the haptic paddle as a real electromechanical system with known parameters in addition to using the haptic paddle as a tool to interact with virtual mechanical systems. The labs integrate haptic technology, LabView, Matlab simulations, and system interfacing in experiments to enhance understanding of dynamic systems and controls.

The broader impacts of this project stem from the fact that the described materials are applied to a required course that is present in most undergraduate mechanical engineering curricula.  A thorough dissemination plan assures broad impact from the improved haptic paddle laboratory series.  Collaboration with colleagues, including faculty at a neighboring institution that serves a substantial number of Hispanic students, assures that the lab series is effective at teaching system modeling and system dynamics concepts to a wide audience.

The well-designed evaluation plan assures that the proposed laboratory series, along with the outreach activities to the University of Houston and prospective Rice students, are rigorously assessed to determine that the objectives are met.

Item	Rice University Haptic Paddle Documents List
1	Bill of Materials
2	Manufacture Document
3	Kit Information
4	Pittman Bulletin LCM
5	Pittman 9434 15V Specs
6	Allegro Hall Effect Sensor Data Sheet

The Haptic Paddle [OkaRic02]

Several modifications to the Haptic Paddle exercises are proposed, with long-terms goals for increased hands-on exposure to system dynamics and control topics in mind.  Additionally, four sets of equipment are requested in order to more efficiently run the laboratory.  In the current situation, each group must schedule an individual time to complete the laboratory exercises, making scheduling difficult and putting unnecessarily high workloads on the laboratory teaching assistants.  The proposed series of laboratory exercises to be implemented at Rice are as follows:

1. Haptic Paddle - Introduction:  The paddle project will be introduced as a means of teaching dynamic systems.  Groups will be formed and lab sessions will be scheduled for the remainder of the semester.  Haptic paddle kits will be distributed.
2. Laboratory Introduction:  Introduction to the rest of the laboratory equipment and the software to be used during the semester, including Matlab and LabView.  Tutorials will be conducted so that students are familiar with all of the tools they will need.
3. 1st and 2nd order electrical systems:   One laboratory exercise involving first and second order electrical systems will be retained but improved.  In previous years, students have built first and second order electrical circuits using a powered breadboard and have provided input signals via a function generator and collected output signals on an oscilloscope.  In the new version of the course, students will still build their circuits as before, but will instead use National Instruments equipment including LabView and NI ELVIS (Educational Laboratory Virtual Instrumentation Suite) to generate input signals and collect output signals for analysis.  National Instruments has offered to provide four complete real-time data-acquisition systems and NI ELVIS systems at half cost.  Funds are requested from NSF to cover the balance.  In addition, National Instruments will provide, at no charge, training for two instructors. Rice already has a site license for all necessary software.  NI ELVIS is a LabVIEW-based design and prototype environment for university science and engineering laboratories that consists of LabVIEW-based virtual instruments, a multifunction data acquisition (DAQ) device, and a custom-designed bench-top workstation and prototype board.  Because it is based on LabVIEW and provides complete data acquisition and prototyping capabilities, the system is ideal for academic coursework that range from lower-division classes to advanced project-based curriculum.
4. System simulation in Matlab:  A laboratory exercise in Matlab for simulation of a dynamic electromechanical brake will be retained from prior years, and simulation of the haptic paddle itself will be incorporated.  The computer systems, included in the budget under materials and supplies, will be outfitted with the latest version of Matlab (under a Rice University site license).  Again, four groups of students will be able to concurrently complete the laboratory exercise.
5. Haptic Paddle - Motor Spin-Down Test
6. Haptic Paddle - System Components
7. Haptic Paddle - Equivalent Systems
8. Haptic Paddle - Virtual 1st and 2nd Order Mechanical Systems:  This laboratory will be a modified version of the Feedback Control lab proposed by Okamura, et al.  A simulated mechanical systems lab, previously implemented with an IE2000 commercial haptic interface as shown in Figure 5, will be augmented so that it will be compatible with the haptic paddle hardware. Students will see a graphical representation of a second order mechanical system on the computer screen. By changing the parameters of the system (mass, damping, and stiffness), they are able to influence the dynamic response of the device.  Because this paddle is designed as a haptic interface, students are able to feel the changes in system parameters.  The limiting factor of this lab in its prior form was lack of sufficient hardware.  Because the lab was outfitted with one IE2000 joystick, only one group of students could complete the experiment at a time. Acquisition of additional IE2000 joysticks is prohibitively expensive, and the systems are of much higher quality than is necessary for the laboratory experiments. By implementing the experiment on the haptic paddle, multiple groups of students will be able to complete the exercise at once. Additionally, by using LabView for the software interface, students will easily be able to change system parameters real-time via the front panel, rather than having to exit the program and re-start as was the case when using the IE2000 and C++ based control software. The visual programming interface of LabView will also make it possible for the students to gain a deeper understanding of the complete functioning system, which was not possible before due to the students' lack of knowledge of C++ programming.

The most notable difference between the documented haptic paddle labs and the proposed implementation is that the computer interface system at Rice University will be based on a National Instruments LabView real-time (RT) system, rather than compiled C code running in DOS to assure real-time operation, as implemented in the original laboratory series.  The cost of half of the LabView RT system is covered by a generous donation from NI, while the other half is requested from NSF.  LabView will be useful not only for the Haptic Paddle experiments, but also for the electrical systems experiment.  Additionally, it will allow for easier expansion of hands-on experiments, both for this course, and for other courses in the system dynamics and control cluster of the mechanical engineering curriculum.