Sensing Patterns

This page discusses the sensing patterns for the Robotic Explorer (RX) Rover, concentrating on the cameras and ultrasonic distance sensors.

Motion

Because the Rover is a mobile platform, sets of images will generally be taken from different locations. If motion blur and vibration do not present a problem, images may be taken while the Rover is moving.

The sensor set can be rotated in the X/Y plane (parallel to the floor). In general, this will be used to sweep the sensing paths back and forth, in order to compensate for orientation inaccuracies in the iRobot base and to provide a "sweep" of sensed territory.

Mounting

Each pair of sensors is co-axially aligned and mounted close together. Ideally, the sensors would be located about five feet from the floor. However, this is limited by our ability to control undesirable motions (e.g., resonance, swaying, vibration).

Sensors

The Rover has three pairs of sensors, pointing left, right, and forward. Each sensor pair consists of a MaxBotix MB1360 ultrasonic distance sensor and a generic USB "web cam".

Camera

The cameras' focal lengths are set to several feet, so most targets of interest should be roughly in focus. Their field of view is roughly conical; it is also deeper, and (at most distances) wider than the MB1360's detection pattern. So, each camera will "see" most targets detected by its companion MB1360.

MB1360

The MB1360 has a detection range of up to 35', depending on the orientation, reflectivity, and size of the target. In loose terms, the detection pattern:

  • begins as a 6' tall, 6' diameter cone
  • turns into a 6-7' diameter cylinder
  • ends with a rounded cap

Diagram

Here is a simplified diagram of the combined sensing patterns. Note that the actual patterns are:

  • 3-dimensional (e.g., conical)
  • irregular in diameter and length
  • dynamic (e.g., travel, X/Y sweep)


This wiki page is maintained by Rich Morin, an independent consultant specializing in software design, development, and documentation. Please feel free to email comments, inquiries, suggestions, etc!

Topic revision: r4 - 10 Aug 2017, RichMorin
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