Configure a Wheeled Base

A wheeled base supports mobile robotic bases with drive motors on both sides (differential steering). To configure a wheeled base as a component of your robot, first configure the board controlling the base and any motors attached to the base.

Configure a wheeled base as follows:

Navigate to the Config tab of your robot’s page in the Viam app. Click on the Components subtab and navigate to the Create component menu. Enter a name for your base, select the type base, and select the wheeled model.

Click Create component.

An example configuration for a wheeled base in the Viam app config builder, with Attributes & Depends On drop-downs and the option to add a frame.

Select the motors attached to the base as your Right Motors and Left Motors. Edit and fill in the attributes as applicable.

{
  "components": [
    {
      ... <INSERT YOUR BOARD COMPONENT CONFIGURATION>
    },
    {
      ... <INSERT YOUR LEFT MOTOR COMPONENT CONFIGURATION>
    },
    {
      ... <INSERT YOUR RIGHT MOTOR COMPONENT CONFIGURATION>
    },
    {
      "name": "<your-base-name>",
      "model": "wheeled",
      "type": "base",
      "attributes": {
        "left": [
          "<your-left-motor-name>" // <INSERT ANY ADDITIONAL LEFT MOTOR NAMES>
        ],
        "right": [
          "<your-right-motor-name>" // <INSERT ANY ADDITIONAL RIGHT MOTOR NAMES>
        ],
        "wheel_circumference_mm": <#>,
        "width_mm": <#>
      }
    }
  ]
}

{
  "components": [
    {
      "attributes": {},
      "model": "pi",
      "name": "follow-pi",
      "type": "board"
    },
    {
      "attributes": {
        "board": "follow-pi",
        "max_rpm": 300,
        "pins": {
          "dir": "16",
          "pwm": "15"
        }
      },
      "model": "gpio",
      "name": "rightm",
      "type": "motor"
    },
    {
      "attributes": {
        "board": "follow-pi",
        "max_rpm": 300,
        "pins": {
          "dir": "13",
          "pwm": "11"
        }
      },
      "model": "gpio",
      "name": "leftm",
      "type": "motor"
    },
    {
      "attributes": {
        "left": [
          "leftm"
        ],
        "right": [
          "rightm"
        ],
        "wheel_circumference_mm": 183,
        "width_mm": 195
      },
      "model": "wheeled",
      "name": "tread-base",
      "type": "base"
    }
  ]
}

JSON configuration file for a wheeled base with annotations explaining some of the attributes.

The following attributes are available for wheeled bases:

NameTypeInclusionDescription
leftarrayRequiredArray with the name of any drive motors on the left side of the base.
rightarrayRequiredArray with the name of any drive motors on the right side of the base.
wheel_circumference_mmintRequiredThe outermost circumference of the drive wheels in millimeters. Used for odometry. Can be an approximation.
width_mmintRequiredWidth of the base in millimeters. In other words, the distance between the approximate centers of the right and left wheels. Can be an approximation.
spin_slip_factorfloatOptionalCan be used in steering calculations to correct for slippage between the wheels and the floor. If utilized, calibrated by the user.

Wire a Wheeled Base

An example wiring diagram for a base with one motor on each side:

Wiring diagram showing a Raspberry Pi, motor drivers, motors, power supply, and voltage regulator for the rover

Note that your base’s wiring will vary depending on your choice of board, motors, motor drivers, and power supply.



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