Robobot Teensy interface
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Software architecture
The software architecture is based on the old NASREM architecture, and this is the structure for the description on this page.
(The National Aeronautics and Space Administration (NASA) and the US National Institute of Standards and Technology (NIST) have developed a Standard Reference Model Telerobot Control System Architecture called NASREM. Albus, J. S. (1992), A reference model architecture for intelligent systems design.)
Figure 3. The NASREM model divides the control software into a two-dimensional structure. The columns are software functions: Sensor data processing, modelling, and behaviour control.
The rows describe abstraction levels:
- Level 1 with the primary control of the wheels for forward velocity and turn rate. This level also maintains the robot pose (position, orientation, and velocity, based on wheel odometry.
- Level 2 is drive select, where the drive can be controlled by just odometry (forward velocity and turn rate) or follow a line based on the line sensor. This level also includes other sensor detections like crossing lines and distances.
- Level 3 is where the overall behaviour is decided and includes camera sensor object detections like navigation codes and other objects.
Level 1; Pose and drive control
Figure 4. The lowest level in the control software. The encoder ticks are received from the hardware (from the Teensy board) into the sensor interface. The encoder values are then modeled into an odometry pose. The pose is used to control the wheel velocity using a PID controller. The desired wheel velocity for each wheel is generated in the mixer from a desired linear and rotational velocity. The heading control translates rotation velocity to the desired heading and uses a PID controller to implement.
More Robobot level 1 details of the individual blocks.
Level 2; drive select
Figure 5. At level 2 further sensor data is received, modeled, and used as optional control sources.
More robobot level 2 details of the individual blocks.
Level 3; behaviour
Figure 6. At level 3, the drive types are used to implement more abstract behaviour, e.g. follow the tape line to the axe challenge, detect the situation where the axe is out of the way, and then continue the mission.
