VEX Grippers (Devices that can attach to objects)

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VEX Grippers(Devices that can attach to objects)
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Outline

• Gripper Theory
• Control
• Speed
• Common Types of Grippers
• Servo Grip
• Motorized Grip
• Pneumatic Grip
• Roller Grip
• Challenge
• Hints
• Use Lock Bars to attach devices to axles
• Use an Ultrasonic Ranger to find objects

Vex Labs Gridiron Robot
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Control

• Holy grail of gripping
• Get object fast
• Hang on
• Let go quickly
• This must be done under excellent control
• Limit switches
• Auto-functions
• Ease of operation

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Speed

• Quickness covers mistakes
• Quick to grab
• Drop re-grab
• Fast
• Servo gripper
• Pneumatic gripper
• Not fast
• Roller gripper
• Motor gripper

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Servo Grip

• Precise
• Limited range of motion
• Limited torque

Roberts ARL robot in 2006
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Motorized Grip

• Can be geared for speed or torque
• More complex

FVC Team 31 in 2005
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Pneumatic Grip

• Powerful
• Reliable
• Requires entire (unreliable) pneumatics system

Some robot
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Roller Grip

• Slow
• Allows for misalignment when grabbing
• Wont let go
• Extends object as releasing
• Simple mechanism

FVC Team 34 in 2005
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Gripper Challenge
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Lock-Bars

• Axles fit through the square holes.
• Bolts fit through the round holes.

• Lock-bars allow for any component to be attached
  to an axle and rotated by a motor or servo.

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Ultrasonic Range Finder

• Detect the distance to the nearest object or wall
• Bounces sound waves off of objects and measures
  the time it takes sound waves to return
• The time can be used to calculate distances from
  3 cm to 3 m

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Thanks/Resources

• Designing Competitive Manipulators The Mechanics
  Strategy
• by Greg Needel (www.robogreg.com)