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NXTway-GS (Self-Balancing Two-Wheeled Robot) Controller Design

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NXTway-GS (Self-Balancing Two-Wheeled Robot) Controller Design

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11 Mar 2008 (Updated )

NXTway-GS Model-Based Design based on Embedded Coder Robot NXT.

Editor's Notes:

This file was selected as MATLAB Central Pick of the Week

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File Information
Description

NXTway-GS is a self-balancing two-wheeled robot built with LEGO Mindstorms NXT and a Hitechnic gyro sensor. This demo presents sample models and documents describe the following contents.

How to Build NXTway-GS
Mathematical Dynamics Model of NXTway-GS
Controller Design for Balance and Drive Control
NXTway-GS Model Illustration
Simulation and Experimental Results

You can simulate NXTway-GS model and generate controller program that can be executed on the NXT. You can watch the movies of NXTway-GS simulation and control experiment at the following URL.

http://www.youtube.com/watch?v=EHPlGTLQHRc


http://www.youtube.com/watch?v=4ulBRQKCwd4

This demo uses Embedded Coder Robot NXT Demo as MBD environment. You need to download it from the following URL before trying this demo.

http://www.mathworks.com/matlabcentral/fileexchange/13399

<Disclaimer>
LEGO(R) is a trademark of the LEGO Group of companies which does not sponsor, authorize or endorse this demo. LEGO(R) and Mindstorms(R) are registered trademarks of The LEGO Group.

Acknowledgements

Embedded Coder Robot Nxt Demo, Nxt Scara (Two Link Planar Robot Arm) Controller Design, and Nxt Ballbot (Self Balancing Robot On A Ball) Controller Design inspired this file.

This file inspired Nx Tbike Gs (Self Balancing Bike Robot By Steer Into Fall), Vu Lego Real Time Target, Nxt Ltd: Line Tracking Dancing Robot Demo, Nxt Scara (Two Link Planar Robot Arm) Controller Design, Nxt Ballbot (Self Balancing Robot On A Ball) Controller Design, and Embedded Coder Robot Nxt Demo.

Required Products Control System Toolbox
Fixed-Point Designer
Simulink Coder
Embedded Coder
Simulink
Simulink Fixed Point
Simulink 3D Animation
MATLAB release MATLAB 7.5 (R2007b)
Other requirements nxtOSEK, Cygwin, GNU ARM
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Comments and Ratings (20)
29 Mar 2013 dirawe  
16 Aug 2011 cheung kwan

can anyone tell me what modification i have to make to use the Lego small wheels?

thank you

11 Jun 2011 Deyan Dobromirov  
22 May 2011 jasan

phillip did you ever find out about the observer implementation?

20 May 2011 jasan

I tried simulating this controller in simulink but i get errors for stating (source function do not exist) such as sfun_bt_tx, sfun_bt_rx, sfun_soundtone, sfun_expfcncallsscheduler. This is weird beacuse with the download of ecrobotNXT in the environment directory these do exist in a C file and as .mexw32. Could the problem be that I'm running this on X64 bit windows 7? Any help will very very much appreciated

30 Sep 2010 Rajasekaran  
12 May 2010 Juan Luna

Philipp, i have completed the controller becoming both dynamics into one, and close the loop control in the wheel dynamics, but i calculated the remain states from the on-board sensors. the controller can track lineal and angular velocities. but the idea of an observer was made by Takachi in his early nxtWAY in with use a ligth sensor to determinate the states (ecrobot exmples).

04 May 2010 Nguyen Hieu  
29 Apr 2010 Philipp B

Hello,

has somebody implented an observer based strategy for the non measured states? Great work by the way, but from the view of modern control theory an observer based method would be even better.

16 Mar 2010 Juan Luna

> Yorihisa Yamamoto

Hello, I first want to say that a person who designs a system so well, as seen in the archives of NXTway-GS, you should take time to support, from the fact that the documentation leaves some empty, they took me a while to realize that control the direction of the robot is in open loop.

26 Dec 2009 Juan Luna

Hello,

I'm trying to enhance (expand) the autonomous mode that controls the NXTway, this by implementing the pure pursuit algorithm, which is executed when these option is chosen.

During the simulation, I found to have some doubts:

1. Why to calculate the current position of the robot you do not use the equation 3.1 on page 7 of document (revision 1.1)?, but instead you use this one:

Z = integral (thetadot * R * cos (phi)) + initial Z;
Y = integral (thetadot * R * sin (phi)) + initial Y

I know that you renamed the coordinates of the robot (pg 56), but despite of the change of coordinates I think the equations are not equivalent.

2. As I could see in the file param_controller.m the maximum linear velocity is 0.3 [m / sec], but you do not put the equivalence with the angular velocity, so: If I put in the gamepad phidot_ref=10, how much it is equivalent in angular velocity?, what I see is that what you do is to add and subtract power to the motors (with a maximum of 25 pwm).

I really appreciate your attention. Thanks in advance, any help you can give me and I am attentive to your answer.

24 Jun 2009 Sam Mirsky

Well done. Good documentation. This demo impresses everyone I show it to.

30 Apr 2009 Yorihisa Yamamoto

> Anand
This file is archived with "Compressed (zipped) folder" shortcut of Windows XP. Please try to decompress it using WinZip or other utilities.

28 Apr 2009 Anand

I am not able to unzip this file. please help

16 Jul 2008 yipeng tang  
29 Jun 2008 CHENMING CHENMING  
22 Jun 2008 CHENMIN CHENMIN  
28 May 2008 Tatsuya Kikuchi

I watched the Self-Balancing Two-Wheeled Robot at Embedded Systems EXPO in Tokyo. It looked like a clown on a monocycle. I think this robot is joyful study case for students.

17 Mar 2008 Anas Obeidat

it's Excellent Simulation to NXT robot and Documentation is perfect.

11 Mar 2008 Diego Barragán

Nice

Updates
07 Nov 2008

1.0 : First edition
1.1 : Added fixed-point controller model
1.2 : modified motion equations

11 Nov 2008

1.2+ Add an annotation to download the generated code into NXT standard firmware

28 Nov 2008

Modified the generalized forces and state equations.
Added simulation movie

26 Feb 2009

updated building instructions
added japanese document

01 May 2009

1.4 Modified text

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