|
|
# Group 8
|
|
|
|
|
|
## Lab Notebook - Lesson 8
|
|
|
## Lab Notebook - Lesson 8 - Journal 1
|
|
|
|
|
|
**Date:** 23/04 2015
|
|
|
|
|
|
**Group members participating:** Ivan Grujic, Lasse Brøsted Pedersen, Steffan Lildholdt, René Nilsson
|
|
|
|
|
|
**Activity duration:** 3 hours
|
|
|
**Activity duration:** 5 hours
|
|
|
|
|
|
## Goal
|
|
|
|
|
|
The goal for the day is to test whether it is possible to follow the Alishan track using only a gyroscope. This approach is very risky since we have no way of sensing if the car follow the lines, but we imagine that it will be very fast if feasible.
|
|
|
|
|
|
## Plan
|
|
|
|
|
|
The plan is to follow the instructions for Lesson 8 [1].
|
|
|
The plan is to conduct various tests to see how the gyroscope behaves when driving on the Alishan track. This data will then be used to make a control the car.
|
|
|
The control strategy for the car is to make the car drive forward until it reaches the first plateau, which is sensed by the gyroscope. On the plateau the car should turn 180 degrees to the right and drive forward until the next plateau is reach and so on.
|
|
|
|
|
|
## Ex 1
|
|
|
## Gyro Offset Test
|
|
|
|
|
|
### Setup
|
|
|
The gyro sensor is placed on the Lego car as shown in the picture below, and both motors are set to full power, while the car is turned upside down. This is down, to test what effect the motor have on the gyro offset.
|
|
|
The gyro measurements are saved using a datalogger. The source code is found in [TODO!!!].
|
|
|
INSERT PICTURE
|
|
|
|
|
|
|
|
|
### Results
|
|
|
In the figure below the raw gyro values are shown. Note that the big offset in the first second is due to pressing the enter button. The measured gyro values are quite varying even though the car is lying still. Therefore an exponential filter is applied to the gyro values.
|
|
|
The filter have the form:
|
|
|
`filteredData(i) = filteredData(i-1)*alpha + data(i)*(1-alpha)`
|
|
|
|
|
|
The filtered gyro data is shown in the lower part of the figure below.
|
|
|
![Upper part: Gyro measurements with both motors turned on at full power. The car was places on the back and did not move. Lower part: Filtered gyro measurements with an exponential filter.](https://gitlab.au.dk/rene2014/lego/raw/master/Lesson7/Images/GyroDataNoMove.JPG)
|
|
|
|
|
|
|
|
|
## Conclusion
|
|
|
|
... | ... | |