2018:Robot Design Details

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Overall design decisions, notes, specifications, and integration items here! Integration Task List (needs link)

Overall Robot Dimensional Restraints

Last updated 1/11/2018

After a coordination session with mechanical subteams we reached the following dimensional guidelines for all subteams to keep in mind.  Sketches (hopefully) to be added Thursday:

  • Drive Base: 
    • We will be a narrow bot with our CUBE intake side(s) being 27.75" and our ramp deploy side(s) being 32.75".
    • We may be a "U" or "H" or solid rectangular drive base frame.  We will have a decision on this by Saturday night.  In the meantime, drive base is focusing on the side rail design.
    • The battery will be located in the back of the drive base. 
    • Bottom Clearance is 1.25 inches, 
    • Top of Drive Base is at 4.25 inches with total gear clearance at 4.83 inches.
  • CUBE Mechanism:  Please note, this section breaks the CUBE mechanism into FOUR parts: Intake ("touch it own it"), Stabilizer (holds the CUBE firmly in an orthogonal orientation), and Arm (moves the CUBE), and Outtake (CUBE exits the mechanism). 
    • Following bumper rules, we have 15.75" of width for all parts of the CUBE mechanism that rests against the drive base frame.  All other parts must deploy over the bumpers.
    • CUBE mechanism must comply with 16" extension rule (be careful with pivots!).
    • "Going Thru the Robot" with the CUBE creates three possible pinch points:
      • A CUBE mechanism with a fixed Arm (that has the Intake/Outake/Stabilizer attached) rotating 180 degrees from robot front to robot back creates an arched ceiling underneath it that the ramp storage must fit under for the width of the Arm/Intake/Outake/Stabilizer.
      • A CUBE mechanism with any Arm design rotating 180 degrees from robot front to robot back creates a path through the center that nothing else can occupy.
      • A CUBE mechanism with any parts that extend outside the drive base require space to store those parts in the Start Configuration that could impact ramp storage.
    • If the CUBE Arm has 1 pivot point (at the base), in order to rotate 180 degrees with Intake and Outtake of the CUBE at the floor (13" CUBE orientation is min on the floor front and back, 11" CUBE orientation is min on the floor front and min. 1" off the floor back) then the centerline of the Arm is approximately 6.5" off the ground.
      • If the Arm has 2 pivot points (at the base and one creating two segments) this constraint may not apply.
      • If the Arm has 2 pivot points and the Intake/Outtake/stabilizer articulates at the end of the Arm, this constraint may not apply.
      • If the Arm has 1 pivot point and the Intake/Outtake/Stabilizer articulates at the end of the Arm, this constraint may not apply.
      • If the Intake/Outtake is attached only to the drive base and the Stabilizer is on the Arm, this constraint does apply. Please note in this instance the ability to Outtake into the SWITCH may be compromised.  It also implys that we are duplicating the Outtake or designing a second Outtake to deploy the CUBE at the front and back of the robot.

Actuators

This is preliminary and subject to change!

Motors

Mechanism Action Minimum Breaker Size Motor Model # Quantity Notes
Intake Grabs the cube and puts it in the hand  30A 775 Pro 2 - one left, one right 15"1 gear ratio - 5:1 and 3:1 in versa planetary gearbox
Arm Pivots arm to robot/front back  30A 775 pro 1 50:1 gear ratio:  5:1, 5:1 in versa planetary, 18T timing pulley on motor, 36T timing pulley  on axle.  If belt fails, wil chane to 15T sprocket on motor, 32T sprocket on axle.
Hand holds the cube as it moves around the robot and deploys the cube  30A 775 pro 1 Starting ration will be16:1 - (2) 4:1 in the versa panetary gearbox.
Lift/Ramp

Lifts the ramp/platform with another team's robots on top

 30A 775 pro 4, 2 per lift 2 Lift systems (jacks) per ramp, 1 motor on each
Drive Base Moves the robot  40A CIM 6 (dropped to 4) Gear ratio 14:64

 

 
 
 

Pneumatics

Mechanism Action - Say what extend and retract do! Cylinder Extend Powered? Extend Exhaust to Atmosphere? Retract Powered? Retract Exhaust to Atmosphere? Working Pressure Estimated Firings per Match
(Sum of all powered directions!)
Notes
Intake Extend = raise intake into robot
Retract = lower intake to retrieve cubes
Bimba M-044-DP. Magnetic 3/4" bore 4" stroke, pivot mount Yes Yes Yes Yes 60 PSI  40

Assumes a defensive game (retract to prevent damage)

RB1 on order

RB2 on shelf

Arm Brake

Extend (spring loaded extension) = disengage brake

Retract = Engage brake

Bimba 041-D. 3/4" bore 1" stroke No Yes Yes Yes 60 PSI

 40

(Review comment: Would expect this to be greater than # of intake firings even under severe defense due to uncertainty of how to use cube and putting in "up" position for any substantial movement)

2 cubes auto, 8 cubes vault, 8-10 cubes switch @ 2 x per cube 

Rb1 & RB2 on shelf

Hand on Arm Retract = "close" hand, tighten on cube
Extend = "open" hand, loosen grip on cube
Bimba 042-D. 3/4" bore 2" stroke No Yes Yes Yes  ?? PSI - 60 may be too high

20

(Review comment: Thought the plan was this does not fire at all and acts as an "air spring"?)

 

2 cubes auto, 8 cubes vault, 8-10 cubes switch 

RB1 & RB2 on shelf

Lifts/Ramps

(One cylinder per platform/ramp but they are plumbed together on same solenoid)

Hold/Release ramp system. Extend = hold ramps up

Retract = release ramps to ground level

 

Bimba 061.5-DXDE  7/8" bore, 1.5" stroke

Double acting, double ended

 Yes Yes Yes Yes 60 PSI

1

 

 

Starts match under pressure

Modifying mounting to use 3/4" bore, 2" stroke double acting on hand.  Will cut off 1/4" pf threaded end and grind down remaining threads. 

RB1 & RB2 on shelf.

 

Consider we may not need to start match under pressure - all loads lateral.  

 

 
 

Sensor Chart

Mechanism Sensor Type Function Attachment Point Notes
Intake Magnetic reed switches (2) on pivot cylinder Senses when cylinder has completed up and down motion On cylinder  
Arm Potentiometer Absolute rotation position of arm. On actual pivot/shaft.  
Arm Limit Switch Tripped at end of travel/at hard stop on front of robot Left side A-frame top front   
Arm  Limit Switch Tripped at end of travel/at hard stop on back of robot Left side A-frame top back   
Hand on Arm Retro-reflective beam sensor Sense cube all the way into hand Mounting is important! Must look "sideways" at the cube where it hits the backstop.  
Ramp Integrated Versa Planetary Encoder Sense travel and speed of lead screw on lift jacks
One phase
4 total, 1 on each jack - Sensor should be at output stage of each gearbox  
Ramp To be Determined Sense when ramp jacks are fully reset (not used during match) 4 total, 1 on each jack - ADD MOUNTING DETAILS ONCE SENSOR IS KNOWN  
Drive Shaft encoders Travel of robot drive base. One phase On center (traction) wheel shaft.  
Whole robot Gyro Sense rotation Must be center of rotation of robot away from excessive vibration sources  
Whole robot Camera

Visual feedback for lining up with exchange?

MS LifeCam HD USB camera

 On the back left corner of the robot in the area set aside in cad  

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