ROBOTICS
In Mrs. Klinger's Grade
Three Class
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Our class worked in teams of 3-4 students to design robots, which would be programmed to perform a task.  Each of our robots were different,  therefore each group had different problems to solve.  However through our class discussions and reflections in our "robotics journals" we found that many of the groups encountered similar problems.

Although everyone encountered some frustrations, the groups worked hard to come up with strategies to solve their problems.  Through teamwork and perseverance our class also encountered many learning celebrations!

As our class explored how to design, build and program a robot, we also discovered we were learning very important skills.  Most importantly, we learned how to work together to solve our design problems.  Our class:

We discovered it was easier to get things done when we listened to each others ideas, and worked together. We also learned that teamwork is an important skill that scientists and engineers use when working on projects.

                     Explore some of the areas we experienced frustrations and learn from our strategies.
 

Gears
Sensors not working.
Structures falling apart.
Motor falling off
Motors going backwards.
Programming bugs.
Friction 

 
Gears:

Although many of us found gears frustrating, we discovered they are very useful in building robots.
We learned that there are many kinds of gears:
 

spur gears
bevel gears
crown gears
worm gear

We also learned that we can use different sized gears to change the speed and power of our drive system.
 

By linking the gears together in a train, you can increase your mechanical advantage. If you need more power you can put a small gear on the driver (on the motor), and a bigger gear on the wheel. This will slow down the speed but increase the power. 

How do you think you could increase the speed of a wheel using gears?  That's right: reverse this system, putting the large gear as the driver and the small gear on the wheel

Frustration: Gear teeth jamming with each other.

Strategies:
1. Changed the size of the gears to get a better fit.
2. Used a 1/3 block (plate), as a spacer to separate the teeth a little bit.



Frustration: Gear teeth skipping

Strategies:
1. Made sure that the motor was held on to robot tightly.
2. Changed the size of the gears to get a better fit.
3. Changed the structure of the robot so the gears would fit better (remove blocks).


Sensors not Working:
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Sensors are very important, because they are what enables our robot to feel and react to their environment.  Our class used different two types of sensors:
 

Light sensors (these sensors recognize when the light levels changed).
Touch sensors (these sensors recognize when its button is pushed in).


Frustration: The sensors do not work.

Strategies:
1. Make sure we remembered to program the sensors.
2. Checked to make sure we added a modifier, telling the program which port the sensor is attached to. (input ports are numbered and are grey)
3. We checked to make sure the sensor cable was attached to the correct port.



Frustration: One group found that their touch sensor would fall off when their vehicle hit the wall, because the vehicle was moving so fast.

Strategies:
1. They tried was making the car go slower, but they wanted a fast car.
2. Use extra Lego pieces to secure the sensor.
3. They switched to a light sensor, because it would react to the wall BEFORE the vehicle hit it, so the pieces didn't fall apart. This worked very well.
 


Structures Falling Apart:
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Frustrations:  Many groups had problems with Lego pieces falling apart.

Strategies:

1. Made sure that we braced the weak sections of the structure.
 

When Lego pieces are lined up, it creates weakness along the joints. 
We discovered that by bracing the joints of the Lego pieces we could strengthen weak parts of the structure.  This is what brick layers do.

 
2. We made sure we secured pieces of Lego that are only hanging on by a bit like sensors, wings and eyes. To do this, we used extra pieces of Lego across the part being attached.


Frustration: The RCX box will not stay attached to the robot structure.

Strategies:
 

1. Use cross-bars and connector pegs to hold them together. 

We learned that the greater the surface area between the two sections, the better they will stay attached.

2. Make sure the RCX is touching as much of the structure as possible.


Motors Falling Off: 
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Frustration: The motor would fall off because of the bump on the bottom of the motor

Strategy:
1. It did not work well, when we simply kept trying to put it on again. We needed to try a different approach.
 

2. A strategy that worked well was raising the height of the bottom around the bump using small and flat plate Lego pieces. This allowed us to connect the motor to a surface with  the maximum surface area possible. 

 
3.  We tried using specialized pieces, that looked like two holed plates that had extra part that slides into the grooves on the side of the motor. It is helpful when you stumble onto solutions like that!  These pieces were further secured with other blocks on the right side.

Frustration: The motor would fall off when we put the pulley on.

Strategies:
1. The pulley was too tight creating too much tension (pulling force), so used a looser band on the pulley.
2. Tried using gears instead of a pulley system.
3. Made sure that the pulleys were lined up and not pulling sideways on each other.
4. Constructed a box around the motor to hold it down.
 


Motors going backwards:
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Frustration: The motor would go in the opposite direction than we programmed it to.

We learned that electricity has direction.

Strategy: We could turn our connecting wires around to change the direction of the motor.
 
 


Programming Bugs:
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Frustration: Our program did not transfer to the RCX 1.0 box.

Strategies:

1. We made sure that we had the RCX box turned to the correct program number (1-5).
2. We made sure that the program we were writing over was on 4 or 5.
 

The RCX 1.0 can contain five different programs.  Programs 1, 2 and 3 are usually pre-set as test programs and can not be overwritten.  Students could download their personal programs on level 4 and 5.

3. We made sure there were no broken wires (grey and black).
4. We made sure our program made logical sense.

We learned that programming requires logic.  You must stop what you start.

We learned that programming is a process, and that one might have to try several different strategies in order to solve a problem.



 
Friction:
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Frustration: Wheels rubbing against the body of the robot.

Strategies:
 

1. Use spacers (bushings) to separate the wheels from the body of the robot. They can also be used to prevent the axle from moving sideways. 

 
2. Use longer axles and move the wheels farther away from the body of the robot. This requires using an axle extender. 



Frustration: The wheels were gripping too well with the floor surface slowing down the robot.

Strategies:

1. Change the tires to ones with less tread, or small surface area touching the ground.
2. One group removed the tire rubber and drove the vehicle on the plastic tire rims!

We learned that friction can be good and bad for a robot design.  Friction is helpful on the tire treads, as it helps the robot grip to the floor and climb slopes.  We found that the tank treads had good friction for climbing.



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