Rover Project Post I

This semester, we have this long waited rover competition using Vex kit to build a small rover that can retrieve a tennis ball. Basically, two teams have their rover set off to catch three tennis balls in the defined field. (I took some notes in google drive while gathering design inspirations during these two weeks. Here they are after some arrangement. I don't mind other teams to see this because it's really a sharing/learning project.)

Two weeks passed and here is a little blogging about the project. 

We are building it carefully step by step to ensure that we are making good moves. For instance, the base structure alone was reassembled about 5 times by today. One slot more or one slot less for allocating the battery; the desired gap between wheels to achieve stability VS the maneuver-bility; the advantage and disadvantage of the sea-saw structure, the proposed string ball-catcher gadget and many more...gosh building this small high-school sweet rover is not easy when you are serious about it!

Including small meetups, we have had meetings this Last Thursday, Friday, this Monday and Friday. As a “planner + teambuilder + secretary”, I am "proudly presented" in every meetups and enjoyed most of them. We see progress in every meetup. I found that unless you be the “Doer”, you will not have the brightest idea or the innovation. It does not come from youtubes, it comes from metal plates and drawing boards!  

I am not sure if this is called INTENSIVE, but well, it was PASSIONATE. I am working hard to win a NO REGRET for my last last project in the uni.

The equipment
Sharp Distance sensor (GP2D12)
http://www.parallax.com/dl/docs/prod/acc/SharpGP2D12Snrs.pdf

Reflective Sensor(OPB704W)
http://roborugby.ucd.ie/docs/OPB704W-reflective_sensor.pdf

Position Servo Motor(Futaba S3003)
http://www.gpdealera.com/cgi-bin/wgainf100p.pgm?I=FUTM0031

Vex Continuous Rotation MOtor (276-2163)
http://www.robotmarketplace.com/products/VEX-276-2163.html

Vex PIC MicroController V0.5
http://www.vexrobotics.com/276-2170.html



Some Rover Examples 

Refer to the gear configuration of this one, and the gear system of this one.

• Translate the power from drive shaft of the motor to the wheeled rear axis
• reduce the wheel speed given the high motor speed

I also like this one which is more of a race car. 

• It runs stably and fast, because the base is flat and low.
• Not sure how good it turns? Gonna do some calculation on that....

And of course lots of people already built robots with Vex, there's this vex simple sonar rover design here, I like how neat this one looks:

• Too bad that it needs two steps to grab a ball: lower the arm and close the hand.
• The hand is too delicate for our task--it's a waste of energy and resources.
• Yet it demonstrate how these frame materials we got can be made use. Sweet! 

Those are all 4 wheels rover, I'm sorry but I'm a little sick of it, can't we have something more "out of the square"...?

Two-wheeled bots
Andurino

• 2 wheeled platform from Make, along with an Arduino and a motor shield from Adafruit.
• the shaft of the continuous motor can be 3D printed
• For compact, small-sized robot
• the sensor movement is very fast ( how to achieve accurate detection?)

Roomba

Visualizing Roomba on the field, I was able to gain some strategies:

- The edge sensor is on the surface of the body. the wheels will hide in the body to prevent the rover from running up hill at the edge.
- The floor is so smooth that wheels should be small compare to the body, not the explorer type
- be able to turn around the corner
- when one rover gets the ball, the other rover might detect the ball in rover1, which is restrained from continue looking for other available balls. So we should make the ball be very revealed in the basket, and be rounded shape so we will not be stuck, and put the sensor in front, not on top.  

Boe Bot

Boe Bot is a cute little commercial rover

• It is a 3 wheeled robot, there's a small supporting wheel behind just like Roomba.
• The "antenna" would be a good idea because then we can stick edge sensor outside and try to avoid clashing with other robots at the same time.  

I can't help to HAHA at this Roboscooper but there's something about this that we can learn: the sound for signal/diagnose, the "robot" outlook, and the simple structure and servo.

Ball Retrieval Mechanism 

I take Prof. Heng's words because they are really helpful. It's like when you read some Wilde, "women marry because they are curious and men because they are tired." you are like, 
1. woa so true I also think so
2. what?! 
3. hmm maybe, but not quite
4. well I didn't realize you can look at marriage this way

And then when Heng said "don't only look at designs that are related, gain insights from outside this project scope" It rang a bell! But wait, maybe not everywhere outside the project, we have to begin somewhere. So here I started to think about other ball-catching activities, and the first thing that came to my mind is Golf. I suppose they must have auto-driving rovers that drive in the field and detect balls to retrieve. Not so smart yet, no auto-driving rovers but these fine ball-catching tools that can well be implemented in our rover!

Golf ball retrieval 
Ball-catching tool design II

Ball-catching tool design II



We can either buy them (maybe not, because a tennis ball is between 65.41-68.58 mm, a golf ball is 42.7 mm) or make them. The second design can be easily made with existing material.

Now, is there tennis ball retriever? (Oh what a lazy bum) Here

So ya, wise man's words opened up the mind like a good book!