Page 23 - Fuel Cell Student Edition
P. 23
X = X * 0.0058
scaled
Y = Y * 0.0058
scaled
As long as the altitude and scaled X and scaled Y Where:
measurements are all in meters, you can now create
a new column and measure the distance between = the angle of the slope in radians
any two scaled points with the following formula:
s = the distance between two
points in 3D space
Z2 = point 2’s z component
scaled
Where:
Z1 = point 1’s z component
scaled
s = the distance between two
points in 3D space
This calculation can be converted to percent slope
X2 scaled = point 2’s x component with the following formula:
Y2 scaled = point 2’s y component
percent slope = tan
Z2 scaled = point 2’s z component
X1 scaled = point 1’s x component
To detect any un-climbable slopes, you can use
Y1 scaled = point 1’s y component the MAX function of your spreadsheet on all of the
Z1 scaled = point 1’s z component values of the percent slope column. This will return
the highest value in the column.
Interval time is the time it takes to move between The energy needed to get from one point to
two points. The rover travels at a constant velocity of another is the sum of the potential energy, kinetic
0.9m/s. energy, and the energy needed to overcome rolling
resistance. If the rover is traveling down a very
velocity steep grade, the recovered energy can exceed the
interval time =
interval distance energy required to go down the hill, and an energy
surplus will be present. For the purposes of this
model, we will assume no limit on the amount of
The rover has a maximum slope traversal ability braking energy that can be stored and 50% efficient
of 60%. Any slope greater than this will cause conversion of this energy from mechanical to
excessive wheel spin and the rover probably won’t electrical.
be able to climb it at such a slow velocity because
there won’t be enough kinetic energy available to The potential energy is easy to calculate. Make a
overcome the reduced traction caused by wheel new column and copy the formula to all data points
spin. To see if our path contains any un-climbable except the first one, which will be zero:
slopes we must calculate the slope of each
interval with the following formula: PE = m * g * h
22 TOTAL REDOX™ – FUEL CELLS TOTAL REDOX™ – FUEL CELLS 23
