TCSS 437 - Robot Challenge 2
Robot #2 can use essentially the same body form as #1. You may need to make
some modifications to the front end to accomplish the goals of this challenge. You
will need to do a fair amount of researh on the Web regarding
sonar range-finding and using light sensors to follow lines on the floor.
Behavior Requirements
Robot #2 will be required to be able to wander in the same fashion as #1. Therefore
if you were successful in getting your wander behavior implemented, then you can
transfer that code to this robot. In addition to the wander behavior you will
need to implement two new behaviors. You will not be using the touch sensors
for this robot. The robot will wander in an essentially open arena (no walls). When
it detects an object in its vicinity it will approach the object and attempt to
come within a very close distance (say within an inch or less). It will act like it is
"examining" the object for a few seconds and then resume its wandering.
This behavior is based on sensory readings from a sonar range-finder array to be
mounted on the front of the robot (actual mechanics of this are up to you and
part of the challenge.) You will get the sensors from me when you are ready to
start building. Note in the figure below the sensors are shown as being out in front
of the robot. You may want to mount them higher on the chasis so that they do not
protrude. Do your research on these sensors and how they work!!!
The second behavior uses the light sensors (you will need two of them). Both sensors
are pointed downward, and you will need to design a support for them that provides
sufficient separation, say two to three inches. The objective here is that as the robot is
wandering, if it happens upon a black line on the floor (a trail) it will abandon
its wandering and follow the trail. The purpose of having two light sensors is
that it can quickly detect when it has lost the line and in which direction it needs
to turn to reaquire it. The objective is to minimize the oscillatory motion that
would occur if you use only one light sensor.
- Wandering:
As in previous assignment.
- Object Detection and Approach:
This behavior differs from the the avoidance in that the robot will actively seek
to approach any solid object in its path. It will move closer to the object and
come to within an inch or two (closer if possible) with its nose directly pointing
at the object.
- Trail following:
If the robot comes upon a trail (black line on the floor) while wondering, it should
attempt to follow the line until it reaches the end. When it does so it should
make some kind of sound (as if it is disappointed!) and then resume wandering.
Performance Requirements
The robot should be able to mediate between the three behaviors in the following
fashion:
- At all times when not stimulated by either an object in front or a trail, the
robot should wander.
- If it detects a line it should follow the line and abandon the wander.
- If it detects an object in front of it, it should abandon wander or trail
following and approach the object.
So, the default behavior is wander. The next priority behavior is follow a trail
if it finds one. And the highest priority behavior is to examine an object up close
if it detects one.
Fig. 1. Robot wandering but detecting an object in its path.
In Fig. 1, the front of the robot shows the new sensor arrays. The two block-shaped
objects in front are the sonar sensors (sonar array) for doing range-finding. The
two circles on either side represent the downward looking light sensors. These
two sensor arrays take up all three sensor input blocks. You should probably plug
the two lights into inputs 1 and 3 and the sonar into input 2.
See me to obtain the extra light sensor and the sonar array.
Fig. 2. Robot approaching an object in a straight line as
quickly as possible.
Fig. 3. Robot wandering toward a trail.
Fig. 4. Robot following the trail. Direction does not matter
in this exercise.
When following the trail the robot should stay as much on top of the line as
possible. It should not lose the line, that is go off so that both light sensors
are on the same side of the line.
When approaching an object the robot should get to the object as quickly as it
possibly can without colliding with it. It should stop no more than an inch away
from the object, but get as close as possible without actually touching it.
Lab Log (journal)
Keep your journal log as before. In this challenge, however, I want you to start
by writing down some important considerations/questions that you feel need to
be taken into account or answered before starting work. This should be in the
form of an outline with major considerations/questions followed by a series of
sub-considerations/questions. For example:
- How are these behaviors going to interact with one another?
- What would happen if the robot detects an object but runs across a line
before reaching the object?
- What happens if the robot detects an object right after starting to follow
a trail?
- ???
- How will the distance (range) measure change if the robot is at an angle with
the front of the object?
- Will the objects always be flat?
- What should I know about sonar range finding to do this task?
- ????
- ?????? and more
As you answer these questions or determine the need for the consideration, record
your findings in the log.
Turn-in and Demonstration
When you are ready to demonstrate your robot, notify me during class
and we will schedule a run. You will get three tries, if needed, to
meet the performance requirement(s). Note, however, that to get three tries you
will need to submit early enough to allow time for these. Other teams will take
priority for their first try if you need additional attempts. These runs should not
need ten minutes, but the conditions are highly variable and may require more time
in some cases.
Turn in your log file and source code in hardcopy in class.
Grading will be based on the following:
- Completeness of log file(s). 30%
- Coding technique. 30%
- Meeting the performance criteria. 40%