Research in Engineering Education Symposium 2011 - rees2009

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requirements. Other movements, as turning or walking were also discarded due to the
facility to perform those movements during a lecture. The usable gestures are:
• Lef_arm_forwards t/right_arm_forwards
• Left_arm_down /right_arm_down
• Left_arm_up /right_arm_up
• Left_arm_out /right_arm_out
• Circle
• Wave
In order to maintain a low error rate we must not distinguish between both hands/arms
gestures. One gesture (possibly circle) must be reserved for “Undo” action, which must be
always present. Additionally, several typical virtual object manipulations must be defined
in each domain of application. For instance, in mathematical derivations a list of basic
linear algebraic manipulations might be:
1. Evaluation of any parentheses, exponents, multiplications, divisions, additions, and
subtractions in the usual order of operations, using associative and distributive
properties properly.
2. Combination of like terms: This means adding or subtracting variables of the same
kind. For instance the expression 2x + 4x simplifies to 6x. The expression 13 - 7 + 3
simplifies to 9.
3. Addition or subtraction of any value to both sides of the equation.
4. Division of both sides of the equation by any non-zero number.
Some of those operations may need additional parameters, which could be provided by
other means (for instance, the insertion of numbers by means of virtual sliders). In
addition, selection of terms for operation should be enabled, and a grammar for the
ordered application of manipulations defined. In this case, creation of initial equation or
mathematical expression is the most complex operation, involving for the definition of a
complex set of ordered actions. Another example would be Laplace circuit analysis. There
are several typical operations to be performed:
1. Include new impedance
2. Include new Input generator
3. Link generators and impedances
4. Select impedance branch
5. Calculate impedance of selected branch
6. Calculate Laplace transform of Input Generator
7. Calculate Output (Voltage or Current) in given branch or between two circuit
knots.
8. Derive Kirchoff equations for circuit
9. …
The application of typical procedures to each domain rapidly grows. This leads to the need
to group actions, so that we use “action” sentences composed of several related gestures,
so that the meaning of each specific gesture changes along time. For instance, including a
Proceedings of Research in Engineering Education Symposium 2011
Madrid, 4 th - 7 th October 2011