Project: Moving base

[azerupi]

Project "Moving base"

This is a tracking issue for the "Moving base" project. This issue can be used to discuss the project, track progress, etc. Specific items should not be discussed here, but on the appropriate sub-issues.

Proposal

This project consist in creating one or two "moving bases" that take care of the low level motion. In the end, we should have a self-contained package that an "intelligence" can easily control.

Big and small base

Eurobot allows a team to have 2 robots, one big and one small. This project proposes 2 different bases that internally use the same technologies.

Here is a sketch of the shapes and wheel dispositions that we consider:

Small base

The small base will be an octogone with perfectly centered wheels.

• This will allow the base to rotate without changing it's footprint.
• Maximizes dimensions (max circumference) while still maintaining straight edges for easy manufacturing.

Big base

The big base will be rectangular and have mecanum wheels allowing it move in any direction. The choice to put mecanum wheels on the big robot and not the small robot like last year is because the motors and wheels take up a lot of space.

The big base will also have a cutout on the side where objects from the field can be "swallowed"

Specifications

A moving base needs to be completely independent from the "brains". We may want to control the base with a Raspberry Pi, using ROS, or from an Arduino. The base should support all use cases and not expect a specific technology.

• Communication
  • CAN
• External connectors
  • 1 CAN connector (eventually a second one for sniffing)
  • 1 power supply connector (12V)
• Motor control
  • Speed control
  • Position control
  • PID (with configurable parameters)
  • Timeout (configurable, if the base doesn't receive commands during the timeout period, it will stop the motors)
• Odometry
  • Motor encoders should be relayed to the CAN bus.
  • External encoders to check for slippage
• Distance sensors
  • At any time, in any orientation, we want to be able to detect an object of 15cm width at a distance of 30cm or less at 360°.
  • The type of sensor used in the base should be "transparent" for the rest of the robot. The data send over the CAN bus should be normalized to send the sensor ID and distance so that we can use ultrasonic sensors and laser sensors interchangeably.
• White line detector
  • The base should be able to detect withe lines and empower the "brains" to follow a white line
  • The base should make it possible for the "brains" to deduce its orientation from a white line

To Do

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This issue will be updated periodically to reflect progress