Method and apparatus for computing surface coefficients of friction
First Claim
1. A method of determining the coefficient of dynamic friction of a surface, comprising:
- imparting an impulse to a block standing on the surface and having a bottom surface of a known test material,sensing the acceleration of the block at a series of times;
generating a series of analog signals proportional to the instantaneous acceleration of the block, each analog signal being generated at a separate such time;
converting each analog signal to a digital signal;
communicating the digital signals to a microprocessor;
recording the value of each digital signal together with its respective time relative to initially imparting the impulse to the block;
displaying a plot of acceleration against time using the recorded digital values and their respective times;
selecting a time for which a coefficient of friction is to be computed;
determining an average acceleration at the selected time by using a plurality of recorded digital values of acceleration following the selected time;
computing the coefficient of friction by dividing the computed average acceleration by the acceleration of gravity; and
displaying the computed coefficient of friction on the video display.
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Abstract
A microprocessor-based interactive apparatus to compute coefficients of static and dynamic friction for a test surface using deceleration data of a weighted block sliding to a rest on the test surface. The apparatus provides an accessible graphical display of the recorded deceleration data which comprises a series of relative time values and associated block acceleration values. A movable cursor permits the user to interactively select the point on the surface for which the coefficient of friction is to be computed. The computed coefficient is then displayed on the graphics display device with the deceleration plot. The cursor may then be redisplayed and moved horizontally with respect to the graphical plot of the deceleration data so that another coefficient of friction may be computed and displayed for a different selected point.
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Citations
15 Claims
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1. A method of determining the coefficient of dynamic friction of a surface, comprising:
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imparting an impulse to a block standing on the surface and having a bottom surface of a known test material, sensing the acceleration of the block at a series of times; generating a series of analog signals proportional to the instantaneous acceleration of the block, each analog signal being generated at a separate such time; converting each analog signal to a digital signal; communicating the digital signals to a microprocessor; recording the value of each digital signal together with its respective time relative to initially imparting the impulse to the block; displaying a plot of acceleration against time using the recorded digital values and their respective times; selecting a time for which a coefficient of friction is to be computed; determining an average acceleration at the selected time by using a plurality of recorded digital values of acceleration following the selected time; computing the coefficient of friction by dividing the computed average acceleration by the acceleration of gravity; and displaying the computed coefficient of friction on the video display. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of determining the coefficient of friction from series of values from a set of acceleration values which represent the instantaneous accelerations of a weighted block moving on a surface, comprising:
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displaying on a video display a plot of the instantaneous accelerations against time; selecting a time at which a coefficient of friction is to be computed; computing the coefficient of friction by dividing the instantaneous acceleration at the selected time by the acceleration of gravity; and displaying the computed coefficient of friction on the video display. - View Dependent Claims (9, 10, 11)
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12. Apparatus for computing the coefficients of friction of a surface, comprising:
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a test block having a bottom surface of a standard test material; an accelerometer connected to the test block; an analog to digital converter adapted to receive analog signals from the accelerometer and convert the analog signals into digital signals; a visual display device upon which the digital signals are plotted; a microprocessor adapted to receive and store digital signals from the converter and to plot the digital signals on the display device; means to select a point on the plot for which the coefficient of friction is to be computed; and means to compute the coefficient of friction at the selected point and display the computed value on the visual display. - View Dependent Claims (13, 14, 15)
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Specification