Tuesday, April 5, 2011
Here is some video of the IGVC robot under remote control at Brickworld Indy 2011. The broken part I was referring to in the video were the linear actuators. The robot currently has 2 Fergelli actuators. The rear of the actuator has plastic bits to interface the actuator into a Technic creation. Turns out if you ram the robot into something, it jerks the affected module around and snaps those important plastic bits on the actuator. Mine cracked, but if the robot were to hit a table or leg again then the actuator's plastic would break for good. Before that happened, groups of little kids were taking turns playing with the robot. I had hordes of little kids and parents intrigued with the robot for several hours. Lots of good MINDSTORMS and FLL chats were had with parents and children alike. It was actually my fiancée that drove the robot into a table and damaged the linear actuator plastic bits.........Jessica!!!
Sunday, March 6, 2011
This robot has had a long time in the making. It was built for a competition called the Intelligent Ground Vehicle Competition - IGVC (www.igvc.org). The goal is to navigate around a closed obstacle course autonomously. The minimum size of an entry must be 2 feet by 3 feet. Most entries into the IGVC are $20,000 to $30,000 university backed entries. The goal of this robot is to enter a LEGO MINDSTORMS robot into the IGVC to demonstrate that a low cost, roughly $2000, off the shelf LEGO “toy” can competitive with robots roughly an order of magnitude more expensive.
I wanted to make a remote control system for the robot to be able to test the mechanical systems. In particular, I need to test the suspension, speed, torque, durability, and other offload qualities of the design. Because there are 6 NXTs, using bluetooth and/or RS485 communications would get very messy very quickly.
I needed a system that was able to talk to each NXT quickly and efficiently. I decided to go with a Power Function system that can communicate to the NXTs using the Power Function lights and light sensors. The Power Function system uses lights to shine upon light sensors which are connected to NXTs. Each of the six wheel modules has an NXT that is associated with the wheel module. When a command is sent from the Power Functions IR Remote, the IR Tower powers an LED to trigger a light sensor which signals the associated NXT to power its wheel. Each NXT has two light sensors. One light sensor triggers the NXT to power its wheel forward, and the other light sensor triggers the NXT to power its wheels backward. What about turning? Two of the six NXTs have an additional two light sensors which are used trigger a Fergelli linear actuator in the same manor. They can be found here: http://store.firgelli.com/lego-actuators.html
It works! Some video to follow.
|Power Functions to NXT Interface using light sensors|
|Power Functions IR Towers|
|Wheel Module Close Up|
Thursday, February 24, 2011
My sumo robot is a rather simple robot. It was inspired by my friend Peter Ehrlich. He built a sumo robot that he called the “Hassenpusher.” His sumo robot was specifically formulated to go against Steve Hassenplug's sumo robot. Peter's robot successfully defeated Steve's robot at Brickworld 2010. Seeing Peter's success, I wanted to improve upon his design further.
The Kinzie version is streamlined and simplified while retaining all of the unique features. When Peter's sumo robot was pushed, it had a tendency to rear-up on its rear wheels which seemed to help its traction. The center of mass of the Kinzie bot also allows it to rear-up in a similar way to Peter's. The drive train also uses a similar gearing set up, and placement of the motors. The plow on the the Kinzie sumo robot is constructed differently than Peters. The Kinzie sumo robot uses an ultrasonic sensor, which is embedded in its plow, to detect the opponent, and a light sensor just behind the plow to detect the edge of the ring.
It is programmed in NXT-G. The program starts off my making the robot turn to find its opponent. When the ultrasonic sensor detects a robot within 15 inches, it moves the robot forward to push the opponent. Meanwhile, if the robot detects a white line with its light sensor, it backs up, turns, and then continues to look for an opponent.
Here are some pictures of the robot from my desk :)