Embedded Motion Control 2018 Group 7

Group Members

TU/e Number	Name	E-mail
0833049	Sam Roovers	s dot roovers at student dot tue dot nl
0886654	Siebrand Keja	s dot c dot keja at student dot tue dot nl
1022624	Milan Haverlag	m dot a dot haverlag at student dot tue dot nl
1279637	Piyush George Alexander	p dot g dot alexander at student dot tue dot nl

Initial Design

The Initial Design document can be found here : File:Emc-designrequirements.pdf

Escape room competition

To escape the room, PICO will first scan its surroundings. By the use of a corner detection program the exit is determined from two laser sets (from the front and back). PICO aligns with the angle at which the exit is detected and will drive forward. A potential field must make sure that PICO does not hit any walls.

Simulation for the Escape room challenge is shown below.

Figure 1 Animation of the Escape room challenge

Potential field method

In order to prevent PICO from crashing into the walls, obstacle avoidance is needed. For this it is chosen to implement potential field method. The potential field method works by combining a attractive force towards a desired set-point with repulsive forces generated from obstacles.

The Attractive force is calculated from the distance between the robot and the set-point. [math]\displaystyle{ r_{att} = \sqrt{(x_{set}-x_{PICO})^2+(y_{set}-y_{PICO})^2} }[/math] and the angle: [math]\displaystyle{ \alpha_{att} = tan(\frac{x_{set}-x_{PICO}}{y_{set}-y_{PICO}}) }[/math]

The attractive force is calculated using a proportional controller:

[math]\displaystyle{ F_{att} = r_{att}*K_{att} }[/math]

The repulsive forces are calculated by taking the inverse of the distance to the wall measured with the laser range finder with the following formula: [math]\displaystyle{ r_{rep}(i) = \sqrt{(x_{wall}(i)-x_{PICO})^2+(y_{wall}(i)-y_{PICO})^2} }[/math] [math]\displaystyle{ F_{rep}(i) = \frac{K_{rep}}{r_{rep}(i)^3} }[/math]

The attractive and repulsive forces are then split in their x and y parts. Their respective x an y parts are then added together:

[math]\displaystyle{ F_{tot}(x) = F_{att}(x) + \sum{F_{rep}(i)(x)} }[/math] [math]\displaystyle{ F_{tot}(y) = F_{att}(y) + \sum{F_{rep}(i)(y)} }[/math]

These Forces are then used to determine where PICO should drive to.

Shortcommings

Due to time constraints the following features are not implemented which would have made the escape room routine a lot better. - the positioning of a waypoint in front of the exit with enough clearing from the walls to drive to. - alignment with the corridor after the waypoint has been reached.