Embedded Motion Control 2018 Group 1

Group Members

TU/e Number	Name	E-mail
1279602	Ahmed Hizar (A.H.) Ahmed Ajmal	a.h.ahmed.ajmal@student.tue.nl
0914013	Jari (J.J.) van Steen	j.j.v.steen@student.tue.nl
0924842	Nazar (N.) Rozkvas	n.rozkvas@student.tue.nl
1279491	Arpit (A.) Aggarwal	a.aggarwal@student.tue.nl
1031018	Willem (W.) Verhoeven	w.b.verhoeven@student.tue.nl

Initial Design

The initial design report can be found at: Initial design report group 1.

Program structure for the Escape challenge

The program has been built according to the Initial Design (Initial design report group 1) having the following 3 structural blocks: Detection, Planning and Control. Each of these correspond to a separate class, functionality of which is described in more detail below.

State flags

Execution of the program is sequential, such that the methods are called one-by-one depending on the state of the robot. The states are controlled by boolean flags, which include

• turn - a flag set to "true" by the planning block when no exit is detected and we wish to turn around to examine the other half of the room. It is unchecked when the control block completes the turn;

• drive_frw - a flag set to "true" by the planning block when exit is detected a PICO has to move in that direction or when no exit is detected and the robot should move in the direction of the furthest point detected;

• turned_once - a flag set to true by the planning block after the first turn in the case exit is not detected form the original orientation. This flag ensures that no continuous turning occurs. The value is set to "false" when drive_frw is set to "true";

• in_corridor - a flag set in the main function when the execution cycle for moving towards the exit it completed. This assumes that PICO is at the exit and a different algorithm for setpoints generation is executed in the planning block;

• escaped - a flag set by the detection block, when no reasonable data is detected after passing through the corridor. As this flag is turned to true, the program should stop executing.

Program classses

The whole program consisted of 4 C++ classes:

main.cpp

• This is the main function where the program starts.
• It initializes objects that are required for the hardware components interaction and program execution (e.g. emc::Rate, emc::IO).
• It initializes the objects storing the sensor data, setpoint for the control loop and the furthest detected point. The later one has the same type as setpoints, however initialized separately since the furthest point is updated every iteration of the main while loop.
• Inside the while loop, the three classes are executed and are constantly updated (Detection, Planning, Control).

detection.cpp

• This is the class that reads data from the sensors, filters it and does detection of primitive shapes and their interpretation. Output is wall line equation, corner points of the exit and one point for the furthest detected distance, with corresponding boolean flags
• Detection file includes methods to detect the walls, find exit and furthest point via line-fitting algorithm.
• The line fitting algorithm provides the equation of a line.
• Method to find exit compares the fitted lines with individual measurements, looking for large neighboring differences in the laser data.
• Method to find walls assumes that the data from the front and the sides of the robot should represent lines. This is verified by searching for laser data with distance closer than a specified value. It then fits the line over those points and spits them to the planning block.
• Method for the furthest point searches for the laser scan with the largest distance data.

planning.cpp

• This is the class that interprets the data and sets the setpoints for movement. The output is relative angle to the setpoint and distance to it.
• It fully exploits the flag commands mentioned earlier and bases it's decision on them.
• There are two algorithms between which, the distinction is done depending on the phase that the PICO is in.
• Room logic method checks all the data provided by the detection class and interprets it in destination points.
• A series of corridor following commands access the corridor data when the flag in_corridor is checked. It sets a setpoint based on the two parallel lines describing the walls, keeping the robot in the middle of the corridor

driveControl.cpp

• This is the class that converts the setpoints to the commands to the actuators and tracks their execution.
• It heavily relies on the odometry data.
• Based on the flags turn or drive_frw it executes the functions for speed regulation till the odometry data states that PICO is at the desired position.

Simulation

With the program described above, PICO was able to escape the room in the simulation.