Carlos Gutierrez
Cluster #5: Computers in Robotics & Biophysics
Beast Claw
Introduction:
What began as simple building blocks for kids can now vary to provide interesting opportunities
for people of all ages, an example being Lego Mindstorm NXT robots. These robots, other than
consisting of certain advance function like sensors, is built from those same simple blocks,
Lego's. The designs of many people who build these kind of robots differ immeasurably and
require a good understanding of programming, providing many fun and educational opportunities
for those make them and those who observe them. I also have my own Lego Mindstorm robot to
to demonstrate with it's own unique structure and program.
Design:
The robot's design is made up of two main structures. The first structure is a tank-like
base. The base has a pair of tank treads on it, each of which is powered by a separate motor,
allowing the treads to move independently. This allows for the robot to go forward, backward,
turn, and rotate. The tank wheels treads use a pulley system to rotate so to provide enough force
for movement, and between both wheels are two bricks to power both the tank and the claw since
both use up too many motors for one brick to handle. The bricks are also linked together with
many braces which also stabilizes the tank. It also has big platform located in top of the bricks so
it can link the tank to the claw which also requires a smaller structure to fully link them together,
which braced diagonally and top to bottom to support the weight of the claw. The claw itself
contains many interesting features, the claw constructed of a maximum of three motors for a long
reach. It also features a few gears which are located in the middle of the claw to provide better
control of the claw and to keep the in a stationary position if it halts when moving so that gravity
does not drag the entire claw down., and a grabbing mechanism at the end of the claw. It also
features to ultrasonic sensors in front of it to tell the robot when to stop and when to lift an object
up.
Construction:
Building the robot from scratch brought up an interesting challenge which involved a lot
of rethinking of the original design of the claw robot in both the base and the claw form both me
and my partner, Neima Kashani, since this was a joint effort. The original design of the robot
used the same amount of motors for the claw yet it had problems getting after falling to the
ground and was difficult to control. To fix this problem gears were place into the claw and
helped to remedy this problem. Another problem was the force of the claw when moving and its
weight on the robot causing the robot to almost fall apart. To to solve this problem braces were
put in several key locations of the tank base, and the part that linked the claw to the to the tank
needed o be rebuilt to better support the claw with many braces and design changes. The claw's
force presented the risk of the robot flipping it over completely so stabilizers where needed in
certain parts to reduce the chances of this occurring. The original design of the wheels had to be
rebuilt since the gears kept on malfunctioning. To tackle this problem this reoccurring problem a
pulley system was introduced onto the wheel's instead of gears which allowed the robot to move
better than before. The original spec was for a remote to be made so that the robot could be
controlled through blue ray, yet it proved to be to difficult so it was decided that sensors would
be used instead. This project required stressful amount of rethinking and reworking of many key
components of the robot which caused almost a sense sever stress that really helped to make both
me and my partner grow a little and improve certain skills.
Program:
//ARMTANline.nxc
int left, right;
#define NEAR 18
int SensorData=255;
task display()
{
while(true)
{
SensorData=SensorUS(IN_1);
NumOut(0,LCD_LINE1,SensorData);
Wait(30);
}
}
task main()
{
SetSensorLowspeed(IN_1);
start display';
OnFwd(OUT_AB,50);
until (SensorUS(IN_1)<NEAR);
Off(OUT_AB);
}
// This program is for the tank base of the robot which tells it to move until it the sensor pick up a
detect a certain object which tell it to stop, causing the next program in the claw to activate.
//ARM.nxc
#define lowerarm OUT_A
#define upperarm OUT_B
#define claw
OUT_C
#define NEAR 10
task main()
{
SetSensorLowspeed(IN_1);
while(true)
{
NumOut(0,LCD_LINE1,SensorUS(IN_1));
Wait(100);
if(SensorUS(IN_1)<NEAR)
{
RotateMotor(upperarm,-50,70);
OnFwdReg(upperarm,0,OUT_REGMODE_SPEED);
RotateMotor(claw,50,110);
OnFwdReg(claw,0,OUT_REGMODE_SPEED);
RotateMotor(lowerarm,70,557);
RotateMotor(claw,-50,110);
OnFwdReg(claw,0,OUT_REGMODE_SPEED);
RotateMotor(lowerarm,100,-557);
} Off(upperarm);
}
}
// This program kicks in right after the other one and basically involves sending orders to all
three motors to move a certain degree, so it can reach for object, a black Lego box, yet if it does
not grab the box in a certain way it will no lift it.
The Idea:
The idea to build was really my partner's idea since my original idea was a certain kind of
plane. He obtained the idea after an outing to Shilling Robotics and seeing one of there robotic
arms. I contributed a few idea's to design by introducing certain changes like the tank wheels and
the braces, but the idea for this robot was really Neima's.
Conclusion:
This whole project was a difficult journey for both my partner and I, especially my
partner, yet we came out of it glad and relived. We encountered many difficulties when it came
to building it and restructuring when certain things did not seem to work. The programming also
provided its own set of difficulties and even caused us to rebuilt certain components of the robot.
If anything was to be learned from this is the importance of preparing for a project, and being
ready for the possible stressful moments that can occur when facing difficulties with a project.
When working with a partner you have be able to compromise that's something learned more
about in this project, and the importance of really working together for a common goal and
developing a strong understanding between the two or the project fails. As they say “Together
we stand, divided we fall”.