We have done many sessions using the Jade robot with
over 2,000 students and 50 or more teachers. With the
exception of two students who wanted to have a plastic
body that they could paint, no one else has complained
about our choice to go with bare PCBs and exposed circuits
all clearly labeled — many have, in fact, complimented us on
making this choice.
Another comment we got from teachers that we’re
very glad we followed up on was the request for the robot
to be able to do “real science.” This led to the inclusion of a
“reflectance spectrometer” (Figure 10) on the Jade robot.
This instrument consists of six different LEDs (each
producing a different wavelength of light) pointing towards
the underside of the robot, with a photodiode that collects
the reflected energy. Based on the brightness of the light
reflected off the surface the robot is running over, a
waveform can be drawn and students can use it to
compare against the known waveforms of different
substances (Figure 11) and make a determination of what
they are.
They also learn about how difficult it is to make a
definitive measurement in the “real world” as many
substances (such as wood with its grain or rocks with
different minerals) do not provide a homogeneous surface
for the measurements. This doesn’t preclude the students
from having a lot of fun doing spectrometer measurements
of the different things in the classroom such as their
clothes, as well as themselves and each other (Figure 12).
It came as a surprise to us, but teachers hate batteries.
They are expensive, they need to be properly disposed of
and, even when locked up, they have the ability to grow
legs and disappear. The Jade robot was designed with a
LiPo battery to allay these concerns. The battery is
actually quite large ( 2,200 mAh) and will easily
power the Jade robot through a normal school day.
Included with Jade is a wall wart charger and a
micro USB cable.
This choice of battery resulted in a significant
amount of pain for me. Most SERVO readers know
that lithium batteries can release an amazing
amount of energy in a short period of time,
resulting is a large release of heat. We were asked
to demonstrate a prototype with all the features of
the finished Jade robot. Up to this time, we had
been using AA cells, and while the battery life was
nothing to write home about, we could get in some
pretty good demos. What we didn’t know was that
there was an intermittent short in the positive
50 SERVO 12.2014
Figure 10. Six LEDs that produce light at different
wavelengths, plus a photodiode make up a reflectance
spectrometer that allows the users of Jade to do real science
and understand some of the challenges NASA scientists have
with their robots on other planets.
Figure 11. Sample reading from the spectrometer using the example
spectrometer application.
Figure 12. With the built-in user interface and spectrometer,
groups of students can work together in very informal
situations, learning Science, Technology, Engineering, and
Mathematics (STEM).
