# Base Fundamentals Beach Cities Robotics – Team 294 Andrew Keisic June 2008.

## Presentation on theme: "Base Fundamentals Beach Cities Robotics – Team 294 Andrew Keisic June 2008."— Presentation transcript:

Base Fundamentals Beach Cities Robotics – Team 294 Andrew Keisic June 2008

2 - Introduction / Agenda Sources Copioli and Patton’s “Robot Drive Systems Fundamentals” presentation

Topics 3 - Introduction / Agenda Center of Gravity Types of Drive Trains Maximizing Design Motor Performance Gear Ratio Calculation

Center of Gravity A point in space where gravity acts Why it’s important? Determines the balance and stability of an object

Center of Gravity Stability - what ball is the most stable? the least?

Center of Gravity What robot is the most stable? The least? How do you know? What systems are inherently stable?

Center of Gravity Putting math behind intuition Stability Triangle h b2b2 b1b1 α1α1 α2α2

Center of Gravity Limit of stability is determined by the CG location In other words – the maximum ramp angle of a stationary robot β1β1 β2β2 α1α1 α2α2

Center of Gravity Why keep it low? Lowering the center of gravity maximizes alpha! Stability Triangle h b2b2 b1b1 α1α1 α2α2

Center of Gravity BCR 2008 FRC initial CG estimate

Type of Bases

Drive train configurations simple rear wheel drive simple front wheel drive simple all wheel drive simple center drive 6 wheel drive tracked drive There is no “right” answer! swerve/ crab drive other?

Types of Bases simple rear wheel drive

Type of Bases simple front wheel drive

Types of Bases simple all wheel drive

Type of Bases simple center drive

Types of Bases 6 wheel drive

Types of Bases tracked drive

swerve/ crab drive

other?

Maximizing Design Designing is all about tradeoffs Speed vs torque Low CG vs reaching high Weight vs features Control vs power

Maximizing Design: Motor Performance

Maximizing Design Requirements Before designing a system, we must know what it needs to do The design requirements usually stem from the game Strategy plays a big part in the requirements Decide the requirements as a team For competitive robots, torque is always needed We’re going to design for maximum torque – pushing ability

weight front The normal force is the force that the wheels exert on the floor, and is equal and opposite to the force the floor exerts on the wheels. In the simplest case, this is dependent on the weight of the robot. The normal force is divided among the robot features in contact with the ground. normal force (rear) normal force (front) Note: Slide from Copiloi & Patton presentation Traction Fundamentals: “Normal Force”

Traction Fundamentals The friction coefficient for any given contact with the floor, multiplied by the normal force, equals the maximum tractive force can be applied at the contact area. Tractive force is important! It’s what moves the robot. normal force tractive force torque turning the wheel maximum tractive force normal force friction coefficient = x weight Note: Slide from Copiloi & Patton presentation

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