Lifts  Four Bar Mechanisms  Rotary Jointed Arms  Scissor Lifts  Telescoping Lifts  Combined Systems Lift Concepts

Overview  Unique: no straight support; but rather linked and folding supports stretch platform upwards  Powered by hydraulics or motors; bumpy ride  Doesn’t travel at constant velocity; faster during middle of journey/slower with more extension Pros  Max height of platform is adjustable  Height determined by # and length of linkages  Great for straight lifts Cons  Requires huge force to start the lift  Synchronizing two scissors is difficult  Complex design Scissor Lifts Lifts

Overview  Basic principle of human arm: shoulder, elbow, wrist  Different types of manipulators (i.e. gripper) can be attached Pros  3 axes of motion: pitch, yaw, roll  Can emulate human arm  Useful when gripping objects is objective Cons  Failure of joint caused by pressure at shoulder and base plate  Each joint requires a motor; operated independently  Thus, programming is tricky Rotary Jointed Arms Lifts

Overview  Simple and effective  Opposite bars remain parallel, retaining orientation of object Pros  Simple, effective  Object retains orientation  Only one joint to motorize  Easily programmed  Provides reach Cons  Joint may endure heavy pressure  Required to lift “outside of the box”  Vulnerable to side hits 4 Bar Mechanisms Lifts

Overview  Commonly used within forklifts and cranes  Extend in one direction  Powered by chain or piston  Also referred to as extension lifts Pros  Extends “within the box”; mechanism protected by base  Operates on a relatively uncomplicated system  Requires only one power source Cons  Multiple segments translate up; higher center of gravity  Can become complex Telescoping Lifts Lifts

Overview  Combining systems can help when one doesn’t cut it Pros  Combines the pros from the various lift mechanisms used Cons  Can quickly become too complex Combined Systems Lifts

Strategy  What is being manipulated? Types of Intake  Continuous  Single Storage Acquisition Zone Placements / Alignments / Accuracy Grip of Object  How much friction is needed? Motors and Servos Limits Gear Ratios Manipulators

1. Find out about the game 2. Make requirements 3. Determine drive train 4. Determine best lift mechanism 5. Determine best manipulator  If robot doesn’t drive efficiently, arm and manipulator will be useless.  K.I.S.S. Strategy Manipulators

Ball  Continuous and single object grabbers are useful Types of Manipulators  2 tank treads horizontally / vertically aligned  3 / 4 prong grabber  2 point grabber / fork  Bucket intake  Roller  Use soft grip to effectively control and contain the ball What Is Being Manipulated? Manipulators

What Is Being Manipulated? Ring  Continuous and single object grabbers are useful Types of Manipulators  2 tank treads horizontally / vertically aligned  3 / 4 prong grabber  2 point grabber / fork  Bucket intake  Roller  Use soft grip to effectively control and contain the ring Manipulators

What Is Being Manipulated? Square  Continuous and single object grabbers are useful Types of Manipulators  3 / 4 prong grabber with grip  2 point grabber  Use strong grip to effectively control and contain the square Manipulators

What Is Being Manipulated? Triangles  Single object grabbers are useful Types of Manipulators  3 / 4 point grabber  Flat bottom and X shaped intake roller  Use strong grip to effectively control and contain the triangle Manipulators

 All items of same size can be similarly stored  Stack  Tank treads  Divide  Dump tank (basket)  Simply grab and drop to goal Storage of Objects Manipulators

 Must be decided with base so arm and manipulator can be stored when Trying to fit the size Effectively obtain objects  U-shaped base  360 ˚ pivot joint (& arm extender)  Manipulator attached to base Storage of Arm & Manipulator Manipulators

 Intake area of the object  Large intake area is optimal During match, easiest and fastest for driver(s) Get multiple objects at once  Keep in mind type of object that will be manipulated Acquisition Size Manipulators

 Scoring object on/into goal must be accurate and easy  Optimal stability and accuracy during scoring  Alignment: know how mechanism works and where it needs to be positioned  Drivers should easily be able to work with placement; manipulator should be accurate Placements, Alignments, Accuracy Manipulators

Why is grip important?  Manipulator has to efficiently contain the object How do you obtain grip?  Friction Grip of Object & Friction Needed Manipulators

 Enable arms and manipulators to move Motors  Can turn a shaft CW and CCW as many degrees as desired  Used for continuous intake Servos  Can turn a shift CW and CCW, but only 180 ˚ in each direction  Used for <360 ˚ pivot joints Motors and Servos Manipulators

Types of Stops/Limits  Hard stop Sturdy metal part of robot Physically doesn’t allow arm / manipulator to go any further May burn a clutch / break motor  Soft stop Limit switches  Limits should be placed anywhere where there is a hard stop Limits Manipulators

 Gear the ratio down Working against a lot of weight 1:2 – one shaft revolution = two motor revolutions  Gear the ratio up Working with less weight and quicker speed 2:1 – two shaft revolutions = one motor revolution  Must have enough torque to pull arm and manipulator up and down  Must have enough torque to contain object that’s being manipulated Gear Ratios Manipulators

 Beach Cities Robotics  Northrop Grumman  OCRLC  Orange Coast College  FIRST  VEX, IFI, VRC THANK YOU!

CHALLENGE! 24 ft. 3 in. Object: Ping Pong BallGoal: Obelisk Objective: Score ping pong balls into obelisk Challenge: Design an arm and manipulator for this task. d: 2 in.