Robobot architecture
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Contents |
Software block overview
Figure 1. The main building blocks.
Software building blocks
Figure 2. The main software building blocks.
Base control
The 'base control' block is the 'brain' of the robot.
The base control is an expandable skeleton software that is intended as the mission controller. The skeleton includes basic functionality to interface the Teensy board, to interface the digital IO and to communicate with a Python app.
The base control skeleton is written in C++.
Python3 block
Vision functions are often implemented using the Python libraries.
The provided skeleton Python app includes communication with the Base control. The interface is a simple socket connection, and the communication protocol is lines of text both ways. The lines from the base control could be e.g. "aruco" or "golf" to trigger some detection og ArUco codes or golf balls. The reply back to the Base control could be "golfpos 3 1 0.34 0.05" for; found 3 balls, ball 1 is at position x=0.34m (forward), y=0.05m (left).
The Python3 block is optional, as the same libraries often are available in C++, and therefore could be implemented in the 'Base control' directly.
IP-disp
Is a silent app that is started at reboot and has two tasks:
- Detect the IP net address of the Raspberry and send it to the small display on the Teensy board.
- Detect if the "start" button is pressed, and if so, start the 'Base control' app.
Teensy PCB
The Teensy board is actually a baseboard used in the simpler 'Regbot' robot. This board has most of the hardware interfaces and offers all sensor data to be streamed in a publish-subscribe protocol. All communication is based on text lines.
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 function: Sensor data processing, modelling and behaviour control.
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.
Velocity control details
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.
Drive select details
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.
