Mars mission: first problems with communication

After completing line-tracking assignment we are now more focused on Mars mission. Technically speaking, we started this mission earlier and worked in parallel. Experience and code which we obtained during line-tracking was partially recycled during Mars mission. For example, tape detection routine is used now as cliff avoiding routine.

However, here we got some problems with Mars mission. They are linked to communication between bricks and Earth computer.

We found that communication is very unreliable and we searched for the reasons first we found that the orientation of the RCX is a key factor. The best orientation is when the RCX is pointing to the ceiling and therefore sends the signals directly to the receiver or reflects the signals over the ceiling to the receiver.The other key factor, is the communication error that happens at the earth computer when the 2 RCXs send at the same time. As a result we changed the configuration of the 2 RCXs so that only the master RCX can send continuously a request to the earth computer for the coordinates and the slave RCX only sends the temperature whenever the master requests. We still can see another problem that when the slave RCX sends the temperature, the earth computer doesn't receive again from the master RCX and we lose communication again. We are now trying to check some points to solve this problem otherwise, as an ultimate solution, we could put the temperature sensor on the master brick and sacrifice the center light sensor.

All these problems and others are solvable. We need to make more tests and adjust both hardware and software so that they will lead to successful mission.

Line tracking: presentation and results

Today we  had a presentation of line-tracking. The presentation itself can be found by following link:
Presentation.pdf

As for questions, jury asked mostly about hardware and team management. For example:
-How did you divide your responsibilities among colleagues?
-Why didn't you choose tank-based chassis?
-Why did you use wires when connected encoders to the chassis?
-How did you calibrate your encoder?

The second part was unsuccessful. On the one hand, rover didn't stuck and make a beep sound. On the other hand it suddenly stopped at the middle of the tape and consequently measured only part of the tape length. Thus, crate of beer went to group five.

Later, we repeated experiment and it worked perfectly. This lesson showed as that we cannot 100% be sure that we solved all possible problems and could predict all of them.

Line tracking: last minute preparation

Here it is. The day of line-tracking is coming. Being in hurry trying to improve as much as possible we did some last-minute preparation.

The main problems were as follows:
-Absence of robustness: if tape has breaks or scratches line-tracking failed
-Measurement error: it was about 3%
-Problem with sound: it sometimes didn't work at all
-Continuing movement after tape finishes.
-Presentation was not self-explanatory enough

Experiments until late night; blood and sweat at the lab... Finally, we fixed problems and created very nice presentation. Video of two various cases is shown below.

Line-tracking: length measurement and sound making

After successful implementation steering and light sensor processing part we started other two parts of this assignment. We tested length measurement and created programme for making sound.

We used information on rotation encoder in order to measure length. We measured length of actual tape and received number of revolutions of encoder. Then using these data we made calibration f sensors and added necessary calculations to the software. Measured length will be displayed on LCD of brick. As a result we achieved measurement with relative error of about 3%.

Also we added sound signal. Now when rover detects the start of the tape it will beep.

Plan adjusting

We updated initial plan. Now when line-tracking is almost finished our main priority is final contest. Taking into account that there are only a few slots in camera using schedule our plan depends on this schedule. Main changes are as follows:

-available camera hours will be used with maximum efficiency;
-since TU/e is closed on week-ends we are going to have additional outside session at Serhat's house
-main attention will be given to integration of three subtasks: edge detection, lake detection and temperature measurement;
-presentations on both assignments will be discussed by us and Jos

Camera tests: results and problems

Today we made our initial experiments using camera in DCT lab. The result is as follows.

-We found optimal view angle and height of mount frame;
-We chose optimal light conditions so that lakes are identified without noise;
-We defined that communication with camera is not reliable so we need to slightly change software part in order to make it more robust to communication loss

Line-tracking preparation and edge avoidance for Lake-finding

After some tests Line-tracking code was furthermore improved. Now its movement is smoother and more precise

Also we started edge avoiding routine. This routine will work in parallel with lake detection and will help rover to avoid falling down from Mars surface. It is based on detection of different value of light reflection on the edge. If left light sensor detects edge then rover stops and front wheel rotates to the right direction on 90 degrees angle. For right light sensor detection it is vice versa. Separately we will add routine for avoiding plateau using central sensor. The programme is not ideal and on the sharp edges when both sensor detect edge it still needs to be improved.