In episode 11 we looked at one of the most important topics for the competition - calibrating the light sensors. In this video I would like to show you how to use a more programmatic approach. This means letting the robot do the calibration on its own. Automatically.
We start a course for following a line with crosses and gaps. This is a challenge that one of the users at FLLCasts.com was trying to accomplish and asked us for advice. We present the whole challenge to you step-by-step. But first, let's also see the whole run of the line following algorithm. With this course, we also do an introduction of using State Machine as a programming pattern.
The robot works on the field and decodes the different colours that represent the rows and the columns.
It's inevitable. While following this gapped line we would reach a gap. The robot must somehow understand that there is a gap and must make a decision on what to do. For detecting the gap we use the Rotation Sensor. Not the most popular, but very convenient in many cases. Check out the video.
We've detected the gap. It's time to move over it. This is difficult because we have to detect where the line is after the 0.1 meters gap on the line following field.
How do you detect a cross-section and move from following the main line to following the crossing line. In this series of video tutorials we are starting with a very simple solution that could work in most of the cases. It is especially useful for the FIRST LEGO League Trash Trek competition where there is such a section.
All worked as expected, up until know because the robot got lost. This happens when we turn right and the line does not continue to the right. Now the robot must somehow understand that it is "lost" and escape.
Building instructions for the LEGO Mindstorms EV3 robot used for accomplishing WRO 2014 mission. It is the full robot with the lift at the top
Modification of the EV3 Competition Robot Full with light sensors attached to the front
Building instructions for a Robot Grabber used in the World Robotics Olympiad competition runs. The grabber is build with LEGO Mindstorms EV3. The base of the robot is available at /materials/69-wro-robot-2014-elementary
This is a real competition robot with three light sensors and a gyro.
Would you like to resolve all the problems with the light/color sensors that you have? And to make all of them work in a predictable, stable way even when using more than one MINDSTORMS colour sensors.
When using Color sensors it is important to calibrate them depending on the light conditions in your venue. In this way, the calibrated sensor will show values between 0 and 100 independent of the light conditions. But using the default EV3 colour calibration available in the colour sensor block could lead to unpredicted problems that are difficult to track and resolved especially when used with multiple Color sensors. So in this series of tutorial we implement the calibration ourselves discussing the principles of colour sensor calibration.
"Array initialization" is the first step in every program that involves Arrays. This applies to most programming languages and for EV3-G it is a must.
In this tutorial, we would show you how to initialize the array and how to extract this logic in a new block
In this tutorial, we would implement a program that finds the minimum and maximum value detected by the sensor and stores this two values in an array.
In the course section for Advance Sensor Calibration we previously showed you how to find the minimum and maximum value for a single LEGO Mindstorms Color Sensor and to store this value in an array. The program was implemented with the EV3-G software. In this tutorial we are going to find the Min and Max for all the four sensors and to store all the 8 values in an array.
Following the Advance Sensor Calibration course section, we found the min and max values detected by each sensor. Now it is time for the real deal of the calibration. Detect the current value from the sensor and find what is the percentage of this value for the range between min and max.
Many times we just upload blocks and leave it up to you to use it. In this tutorial, I would like to show you how to use the implemented blocks. How to import them into the EV3-G software. How to see them in the palette. How to drag and drop them to build a working program.
Implement the program for array initialization.
Follow the video tutorials for initializing arrays and implement the program.
As an exercise try to implement the calibration of the minimum and maximum values for a single sensor.
Following the previous tutorials from the course, implement the calibration of the minimum and maximum values.
