LESSON 03 – CHASSIS DESIGN

 


LESSON NOTE

INTRO

 

The chassis of a robot is the structural base that gives the robot its shape and size.  It includes the drive train that allows the robot to move around.

 

CHASSIS DESIGN

 

Chassis design needs to consider the following:

  • required final size of the robot,
  • the needed drive train,
  • the capability of the robot,
  • the mounting requirements for any manipulator mechanisms
  • the type of payload that the robot must carry.

 

EXAMPLES

 

Below we will look at a few chassis and discuss a few attributes.  We will not look at the drive train until later.

 

EXAMPLE 1

The rectangular chassis below allows for a large surface for top mounting mechanisms.  Placing wheels on the outside does risk the wheels getting caught on objects or even getting bumped and eventually getting loose (specially in a contact-filled competition).  Each side has two structural members allowing for each shaft to be well supported.

 

 

 

EXAMPLE 2

The C-shape chassis allows less convenient top mounting options but does allow for mechanism access between the two front wheels.  This is often useful for picking up objects on the ground.

 

 

 

EXAMPLE 3

 

The small chassis below offers little mounting space but does allow the robot to move more easily in tight spots.

Image result for vex square bot chassis 

 

EXAMPLE 4

 

The H-shaped chassis below allows floor access at the front and back of the robot.  In exchange, it doesn’t offer easy mounting options for mechanisms.  This design hides the wheels insides the side structural members better protecting them from contact.  The structure used is wide C-channel making the chassis more solid but also heavier.

 

 

DRIVE TRAIN DESIGN

 

The drive train consists of the parts that make the robot move.  This includes the motors, any gears, sprockets and chains as well as the wheels. 

 

Drive train design needs to consider:

 

  • torque requirements
  • speed requirements
  • turning requirements
  • movement type
  • terrain type
  • required room on the chassis

 

CHASSIS & DRIVE TRAIN INTERCHANGEABLE TERMS

 

We have separated chassis design and drive train design in order to simplify our discussion.  In reality, both have to be done at the same time.  So much so that we often use “drive train” and “chassis” interchangeably to refer to both the structure and the moving mechanisms.