Lynbrook RoboticsFIRST Robotics Team #846

Ball Roller Control System

• movable roller is ideal
  • prevents too much force being applied on the roller when the robot drives over the ball
  • space issue, there may not be enough room
  • maybe have the motor on top of the roller, and the pivot point of the roller will not obstruct a kicker
    • might limit how much the roller can move up and down
• how to reliably roll the ball towards the center of the robot
  • at a shallow angle from the forward plane, the ball doesn’t want to go towards the center

Kicker

• kicker size
  • smaller, compact kicker is better because the force is transfered better
  • a larger kicker would allow you to shoot the ball without having to position it in the middle
    • will need reinforcing structure to prevent the sides from flexing
• again, room conflict with the roller
• torsion spring fixation
  • if attached to either kicker or to frame, then we’ll need a guide to prevent the torsion spring from turning out of place
  • if fixed to both the kicker and the frame, then we will need a torsion spring that is more than 90 degrees
  • different locking system to hold a cocked kicker in place
    • implement a spider locking system, which is a set of teeth on the kicker leg, and the shaft, and the once the teeth pushes the kicker to the cocked position, the teeth on the shaft retracts
    • trigger can either be a ratchet or teeth that locks on the base of the kicker
    • low friction surface on the ratchet

Alternate Winch

• telescopic design based on that of Howler (2008 robot)
  • better thought out, easier to design due to previous experience
• maybe implement a spring loaded stage similar to the working of a magic cane

This is the build season log for Lynbrook Robotics.

Software & electronics

• have better layout for the wires
• start with the programming soon
• Mr. Yang (Annie’s dad) will help with this
• Use proximity sensor to detect the balls
• Shooting the ball accurately at long range may be hard
  • passing the balls to the near field may be good enough
• We might use a vision camera for a cockpit view
  • can be used after autonomous mode to provide aim assist

Sensor inventory

• Encoder on gearbox
• Hall-effect sensor for speed
• Camera
• Ultrasonic
• Infa-red
• Gyro

Robot arm design

• the arm raises sideways, and reaches up to 90 inches
  • if the arm isn’t perpendicular, then the total length of the arm may extend beyond 90 inches to achieve that height
    • may not pass safety inspection
• the hook accounts for some of the height of the arm
• robot must be right next to the tower to grab on
  • alternatively, the arm may swing beyond vertical
• folding arm vs. telescopic arm
• have a cable on the opposite side of the arm that also pulls the robot up
  • prevents the torque from having too much stress on the arm base
  • expose the smooth side of the robot to rub against the platform if necessary
• have a corkscrew that grabs onto the tower

Movable ball-controlling roller?

• acts as a tensioner
  • prevents the roller from applying too much force on the ball, and prevent driving over it
• wooden mockup shows that there is very little room for the roller, so an adjustable roller will be difficult to implement
  • the kicker shouldn’t hit the roller
  • a spacer that prevents the kicker from following its motion through
  • a kicker that can vary the amount of force that it provides

Kicker

• doesn’t necessarily have to hit the ball directly
  • spring loaded contraption hits a hammer that transfer the force to the ball
  • may be more flexible

Motor inventory

• CIM – 5
• Fischer-Price – 2
• Window Motor – 2L, 2R
• RS555 (30W) – 1
• RS??? – 1

Motor application (subject to change)

• Drive train – 2 CIM
• Winch – 1 CIM
• Righting & arm – 1 CIM
• Front roller – 1 RS
• Kicker – probably 1 CIM
• Kicker charger – probably 1 RS
• Climber – 1 RS or 1 Fischer-Price

Dear Diary,

No design meeting today but time to go on Youtube. Teams started posting simple tests and Chief Delphi is buzzing with activity. Plenty of new threads and posts J. Everyone is thinking and waiting for tomorrows design meeting. Mr. G brought in a hammer today and we tried hitting the ball in different heights. We are going to post the video on Youtube for other teams to see as well. We were able to make some conclusions regarding where to hit the ball (low, center, or high) Spin is important, but not as much as getting airborne.

Officer meeting and then back home to read more threads on effective drive trains. Some people are suggesting a robot with 8 small wheels. I don’t understand why, but I’ll bring it up at the meeting tomorrow and see if someone can explain it to me. Hopefully we’ll take 6-8 people to Mr. Hass’s house and build this weekend. We want to get the Tower and platform does. Then all that remains is the goal (we may not build one. Don’t know yet).

-Chinmay

Dear Diary,

Refer to Mr. Xie’s spreadsheet for details. Today was spent largely clarifying rules and discussing strategies. We haven’t considered how to do many of the tasks because we are still largely focused on deciding which tasks we care about. Random idea of having a swinging weight to help give us momentum but not practical because a large weight and moment are needed. Annotated agenda:

1. Decision on required functionalities of this robot (still no real conclusions

2. Review previous designs of our robots and other team robots for the same or similar functionalities (04 Hang em’ High)

3. Understand and update rules (worked a lot with the subtleties of the rules. No updates b/c Q and A not up yet. )

4. List questions or issues related to the functionalities.  Resolving these questions and issues will lay out our design requirements.  Some prototyping tasks may emerge. (building a kicker, possibly a vacuum? take it off 08?) Conceptual design will possibly be discussed at the same time. (not here yet)

Questions to answer as soon as we can are…

- What is the initial speed for a ball to go over one bump or two bumps assuming a ball roll forward without rolling friction resistance.  (***can’t ever really roll ball over 2 bumps*** if it’s going to fast, will get airborne off the top of ramp. Topspin helps)

- Design Issue:  Given the restriction of that a ball is only allowed to get into a robot frame 3 inches, what is the best way/design controlling a ball in our robot possession, not arbitrarily bump a ball away?  How can a robot get possession of a ball if the ball touches boundary/wall? (does it need to be in possession ever? Is simply kicking away such a bad idea?)

- For going over a bump, what is min. robot bottom clearance to the floor? What is max. height of the center of gravity before tipping (assuming the center of gravity is along the vertical center line of a robot)?

- For hanging robot, if elevating speed is 1 m/s and total robot weight is 150 lb (68 kg), what is power required to do that?

-Autonomous mode will be an afterthought not of utmost importance.

-Chinmay