BrickEngineer: LEGO Design

LEGO Engineering for LEGO NXT and Robot Enthusiasts

KnuthLab LEGO Exploration Rover Featured on Japan’s NHK World Network


KnuthLab Exploration Rover Featured on NHK WorldNet

KnuthLab Exploration Rover Featured on NHK WorldNet

The Knuth Cyberphysics Laboratory focuses on studying the fundamental physics governing the processes of information-driven systems.

At present we are focused on two research projects. The first, which is funded by a NASA SBIR grant, aims to develop Bayesian vision-based navigation systems for future NASA missions. The second, which has been funded by NASA in the past, is focused on developing intelligent instrumentation in the forms of science platforms that can autonomously decide on and perform their own experiments. Both projects, which are focused mainly machine learning software, rely on robotic platforms that we construct out of LEGOs. LEGO bricks are prefabricated plastic parts that can be assembled and disassembled in a matter of hours. We have found them to be quite versatile and capable, as well as being inexpensive.

On Wednesday Sept. 12, 2012, the Knuth Cyberphysics Lab at the University at Albany was visited by a television crew from NHK
World Network (Japan Broadcasting Corp.). They were working on a piece focused on the Mars Curiosity rover and were interested how NASA missions fostered creativity in robotics. In our lab, they were specifically interested in the fact that we used LEGO robots to test software for funded NASA projects. The program aired in Japan on Sept 15, 2012.

Here is a link to the show’s website.
http://www.nhk.or.jp/worldnet/archives/year/detail20120915_202.html

Here is the photo caption from the website:
NASAは自由な発想で宇宙開発に挑むために、
あるユニークな方法を取り入れている。その方法とは、おもちゃにもなっているブロック。次世代の探査機を研究しているチームでは、ブロックを使いながら設計予想図のイメージを共有し、問題点を洗い出している。何度も手軽に作り直すことができ、自由な発想を形にしやすいのがブロックの強みだ。キュリオシティの開発でもブロックを使って検討作業を行った。研究開発の担当者は「ブロックを使うと、いいアイディアかそうでないかはすぐにわかるので方針転換も早くなる」と話す。

The Bing translation is:
Incorporating a unique way for free thinkers NASA challenge space development. How is block have become toys. Share the anticipated blueprint image team studies the next-generation spacecraft, while using the block and identify the problem. Easily can be recreated many times, easy and free thinking-is an advantage of the block. Using the block curiosity Inc. developed and went on. Research and development professionals “using blocks, a good idea? so readily detect if it isn’t policy change even faster” and speak.

The Knuth Cyberphysics Lab website can be found at:
http://cyberphysics.rit.albany.edu/
and
http://knuthlab.rit.albany.edu/

Learn more by checking out this related post”
http://www.brickengineer.com/pages/2012/01/06/knuthlab-lego-exploration-rover/

KnuthLab LEGO Exploration Rover

Image of KnuthLab Exploration Rover

KnuthLab Exploration Rover with Researchers A. Fischer and N. Malakar

The Knuth Cyberphysics Laboratory in the University at Albany Physics Department has developed the KnuthLab LEGO Exploration Rover, which acts as a testbed for robotic intelligence and navigation software. Development of this rover was funded by a NASA SBIR Award (Advanced Bayesian Methods for Lunar Surface Navigation) through Autonomous Exploration Inc. as well as a University at Albany Faculty Research Award (Developing Robotic Explorers, PI: K.H. Knuth).

The LEGO Exploration Rover is powered by six NXT Standard Motors in a Rocker-Bogie suspension system used in all of the NASA Mars rover designs. The rover is approximately 1.5 ft high with a 1 ft x 1.5 ft base. It is larger than the NASA Sojourner Rover, which was part of the Pathfinder Mission to Mars in 1997, and smaller than the Mars Exploration Rovers Spirit and Opportunity. It can safely carry a payload of 8 pounds.

Image of KnuthLab LEGO Exploration Rover

KnuthLab LEGO Exploration Rover


The LEGO Exploration Rover has two laptop bays built into the box-like frame in which it can carry two Asus Eee Laptops for onboard processing. The wheels are controlled by two LEGO NXT bricks, which can communicate with the laptops via Bluetooth. The rocker-bogie suspension and low speed allows it to handle relatively rugged terrain and steep grades.

The white frame mounted on top of the rover is the Bayesian Vision-Based Navigation System being developed by Autonomous Exploration Inc. for NASA.

Check back, as we will be posting videos of its operation and discussing some of the important design features.

A Catalog of Omni-directional or Holonomic Wheels for LEGO Robots

I have been researching the possibilities for omni-directional or holonomic wheels for LEGO robots. An omni-directional or holonomic wheel is one that can roll not just backwards and forwards, but sideways as well.

New Rotocaster Omni-Directional Wheel

New Rotocaster Omni-Directional Wheel

While these are often used on robots with three wheels where all three rotate at different rates allowing the robot to go in any direction,

Three-Wheeled Omni-Wheel Prototype by Xander Soldaat at Bot Bench

Three-Wheeled Omni-Wheel Prototype by Xander Soldaat at Bot Bench (click on image to see more)


I am interested in using these on a rover that can employ differential steering smoothly without skidding.

There are several different options that one can consider. LEGO purists may consider making their own omni-directional wheel designs out of only official LEGO parts. Another option is to purchase manufactured omni-directional wheels. These come in two classes: those that are designed to be LEGO compatible, and those that are not LEGO compatible. In the latter case, one would have to construct some kind of coupling mechanism to enable the wheel to connect to LEGO parts.

Here are some of the options that I have found.

Omni-Directional Wheels Constructed from LEGO Parts

Omni-Directional LEGO Wheels by Xander at Bot Bench
These wheels use the LEGO pulley to get a six-fold symmetry. Each “wheel” uses 12 LEGO wheels. For archiving purposes, here are three pictures. Please visit Xander at Bot Bench for larger images and more details.

Omni-Directional LEGO Wheels by Xander Soldaat at Bot Bench

Omni-Directional LEGO Wheels by Xander Soldaat at Bot Bench

Omni-Directional LEGO Wheels by Xander Soldaat at Bot Bench

Details of Omni-Directional LEGO Wheels by Xander Soldaat at Bot Bench

Omni-Directional LEGO Wheels by Xander Soldaat at Bot Bench

Details of Omni-Directional LEGO Wheels by Xander Soldaat at Bot Bench

This amazing tank by Peer Kreuger also sports omni-directional wheels made from LEGO parts

LEGO Tank with LEGO Omni-Directional Wheels

LEGO Tank with LEGO Omni-Directional Wheels

The Omni Bot v2 by jason701802 also sports omni-directional wheels

Omni Bot v2 by jason701802

Omni Bot v2 by jason701802

LEGO-compatible Manufactured Omni-Directional Wheels

This LEGO-compatible wheel is made by the School of Robotics

School of Robotics Omni-Directional Wheels

School of Robotics Omni-Directional Wheels

Rotacaster makes a LEGO-compatible omni-directional wheel:

Rotacaster Robot Wheel (LEGO-compatible)

Rotacaster Robot Wheel (LEGO-compatible)

Rotacaster is also coming out with a new design

New Rotocaster Omni-Directional Wheel

New Rotocaster Omni-Directional Wheel

Rotacaster also produces several non-LEGO compatible designs.

Tetrix also makes LEGO-compatible Omni-Directional Wheels

Tetrix Omni-Directional Wheels

Tetrix Omni-Directional Wheels

General Manufactured Omni-Directional Wheels

Mecanum Omni-Wheel Designed by Bengt Ilon in 1973 at the Mecanum AB Company

Mecanum Wheel

Mecanum Wheel

Mecanum Omni-Directional Wheel

Mecanum Omni-Directional Wheel

Vex Omni-Directional Wheel

Vex Omni-Directional Wheel

Vex Omni-Directional Wheel

Damon WH-01 Omni Directional Wheel (hexagon hole)
(Outer Diameter:60mm, Inner Diameter:11mm, Material: Nylon)

Damon WH-01 Omni-Directional Wheel

Damon WH-01 Omni-Directional Wheel

Kornylak Omni-Directional Wheel

Kornylak Omni-Directional Wheel

Kornylak Omni-Directional Wheel

Kornylak Transwheel

Kornylak Transwheel

Kornylak Transwheel

Kornylak Omni-Directional Wheel

Kornylak Omni-Directional Wheel

Kornylak Omni-Directional Wheel

Knuth: Developing Robotic Scientists for Space Exploration

The University at Albany (SUNY) has highlighted Knuth’s research in a recent news piece.

UAlbany Professor Kevin Knuth with a robot built from LEGOs. (Photo Mark Schmidt)
UAlbany Professor Kevin Knuth with a robot built from LEGOs. (Photo Mark Schmidt)

Kevin Knuth has a laboratory in the physics department of the University at Albany that is filled with LEGOs. The bricks are relatively cheap and can be used to rapidly prototype a robot’s body. Knuth’s robots are being programmed to solve such problems as mapping complex terrain.

At UAlbany Day on Saturday, Oct. 25, he will give a demonstration on Robotics and Robotic Exploration in Life Sciences Room 143 at 10:45 a.m.

More here:
http://www.albany.edu/news/update_4522.shtml

Building instructions for the robot shown in the UAlbany article can be found on Brickengineer.com

Visit Autonomous Exploration News for information on Knuth’s company Autonomous Exploration Inc.

Visit Robots Everywhere for a general blog on robotics news.

Center of Mass of LEGO NXT Motors

I am working on designing a walking machine, but I needed to know the Center of Mass of the LEGO NXT Motors.  When using Newton’s Laws to compute the forces on the system, we can treat the motor as if all of its mass is located at a single point.  The Center of Mass is the location of this point.

Hanging an NXT motor to find its center of mass.

There are several ways to find the Center of Mass of the motor.  The most straightforward way is to hang the motor from an axle placed in one of the holes.  The motor will orient itself so that the Center of Mass lies directly below the axle.  By hanging a mass on a string from the axle, the Center of Mass must lie somewhere along the line defined by the string. 

The Center of Mass Lies along the line defined by the vertical string

After performing this experiment, I placed a small piece of Scotch tape over the string so that I can keep track of where that line is.  I then cut the string off of the axle.

A piece of Scotch tape holds the string in place

Now to find the precise point, we simply perform the experiment again, but place the axle through a different hole.  This gives us a second line.  Since the Center of Mass must be on both the first line and the second line, it is located at the intersection of these two lines.

The intersection of the two strings indicates the position of the Center of Mass

The Center of Mass is very close to being aligned with the holes on the motor.  Below is an MLCAD image of the NXT motor (from Philo).  I have overlayed a Cartesian coordinate system that corresponds to that used to define the 3-D image file.  The origin of this system is at the center of the axle hole on the motors drive axis.  This is perfect for me since I will be rotating the motor and trying to compute the position of the Center of Mass after the motor has rotated through some arbitrary angle.

The dimesions of the LEGO NXT Motor

This image not only helps with identifying the Center of Mass of the NXT motor, but also in understanding the dimensions of the NXT motor overall.

Kevin Knuth
Albany NY

Matlab Package for LEGO Mindstorms

I recently received a comment on my post on controlling NXT robots with Matlab that pointed me to the RWTH – Mindstorms NXT Toolbox for MATLAB®, which is a public domain Matlab package that enables one to interface with and control LEGO mindstorms.

The RWTH – Mindstorms NXT Toolbox for MATLAB® was developed as a student project in the Institute of Imaging and Computer Vision at RWTH Aachen University in Aachen Germany. It provides a Matlab interface with the NXT brick that includes Bluetooth communication, sensor interface and motor interface. It requires a working Matlab license, of course.

The package is very easy to set up. It took me less than ten minutes to successfully test the example programs over Bluetooth.

There are some very nice motor features, such as motor synchronization and speed ramp-up and ramp-down.

I have yet to explore how easy it is to modify or extend the code, but it ought to be a straightforward matter.

The package can be downloaded from
http://www.mindstorms.rwth-aachen.de

Kevin Knuth
Albany NY

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