Getting used to the NXT programming environment. Justin programmed the ball grabber.[MEDIA=1]Â We are having some difficulty connecting to the NXT via bluetooth from Windows XP. However, bluetooth works like a charm from MacOS. Getting bluetooth to work is critical for the project, so we will need to do more troubleshooting.
Having learned the NXT programming environment, the next step in the project was to become familiar with Bluetooth. My endeavor in to the realm of the Bluetooth world started very promising, as I was able to connect my computer to the NXT brick despite receiving a warning message that my Bluetooth radio was incompatible with the NXT. With the Bluetooth working, I decided to send a copy of the grabber program to the device. This worked flawlessly.
Since I ultimately was looking to use Bluetooth as a method to remotely control the robot, I began exploring this possibility. I started by looking in the user manual that came with the NXT software. As my query, I typed in “Bluetoothâ€. I soon discovered that Bluetooth can be used in one of two ways: to send a program wirelessly from your computer to the NXT brick or to send messages between other NXT bricks. Because of the limited information about Bluetooth, I decided to move my search to the internet.
In doing so, I started by looking at the Lego Mindstorms website, http://mindstorms.lego.com/. I quickly came to the conclusion that the information provided on this site was extremely limited. As such, I moved my query to the web. When searching on the web, I came across a few blogs that briefly mentioned Bluetooth. I also found some experiments that were centered on the use of Bluetooth as a means of controlling an NXT robot wirelessly. However, most of the information I found dealt with the fact the people were having trouble getting their computer and the robot to connect using Bluetooth. After enduring much frustration, I decided to turn off the robot and my computer and come back to it the next day.
After charging the batteries, I decided to test my latest and greatest program. However, when I set the car on the floor, I realized I did not know how far away I had to put the grabber from the ball. This was because I no longer used the push of the touch sensor to open the grippers. Instead I had designed the robot to travel a set distance, three revolutions of the wheel, and then open the grippers. To figure out the distance I needed between the robot and the ball, I programmed the motors on the robot to make one revolution. I then measured the starting and ending point of the robot to determine the distance it traveled. Then, using the diagram supplied with the NXT kit, I measured the distance between the stand and the robot as shown in the diagram below.
As it turns out, the distance is two revolutions. Going back to the program I created, I changed the amount of revolutions for each motor to two. After making those changes I again tested the program. To my excitement, the grabber was able to grab the ball while only slightly moving the stand. Since the stand essentially stayed in place, the robot was able to drop the ball back on the stand on its return trip.
Considering where I started from, getting the “grabber program†to work was very rewarding. The time and effort put into it had lead to success. Overall, not only had I made a working program, but I had also learned how to use the NXT programming environment, the goal of this task.
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