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Dual Drive, Quad Holomonic Platform
I've been working on a new LEGO Mindstorms NXT Dual Drive, Quad Holomonic Platform. This Robot uses dual Rotacaster Omni-wheels on each of the four axis's. The Robot also uses four NXT Ultrasonic Sensors between each of the four axis's. The four Ultrasonic Sensors work in 'MODE 3: Event Capture Mode'. The Ultrasonic Sensors are cycled through 'one-at-a-time', to avoid interference between each of the sensors.
About this creation
I have built three versions of this Robot:

Version One uses Four Large Power Function Motors too drive the 4 axis's, controlled via the Power Function Infra-red Protocol.


Quad Drive Holomonic Platform using Power Function Control via Mindstorms NXT


Quad Drive Holomonic Platform with Power Function Control



Quad Drive Holomonic Platform CAD View Quad Drive Holomonic Platform CAD View
Quad Drive Holomonic Platform CAD ViewQuad Drive Holomonic Platform CAD View
Quad Drive Holomonic Platform CAD ViewQuad Drive Holomonic Platform CAD View

Quad Drive Holomonic Platform with Power Function Control

Version Two uses Four Large Power Function Motors too drive the 4 axis's, controlled directly via the NXT Birck's Motor Ports. Opposite Motors are paralleled to each other. One pair is connected to Motor Port 'A' and the other to Motor Port 'C'.



Quad Drive Holomonic Platform with NXT Controlled Power Function Motors




Quad Drive Holomonic Platform with NXT Controlled NXT Motors Using Mindsensor NXTMMX

Quad Drive Holomonic Platform with NXT Controlled NXT Motors Using Mindsensor NXTMMX
Quad Drive Holomonic Platform with NXT Controlled NXT Motors Using Mindsensor NXTMMXQuad Drive Holomonic Platform with NXT Controlled NXT Motors Using Mindsensor NXTMMX
Quad Drive Holomonic Platform with NXT Controlled NXT Motors Using Mindsensor NXTMMXQuad Drive Holomonic Platform with NXT Controlled NXT Motors Using Mindsensor NXTMMX

CAD of Quad Drive Holomonic Platform with NXT Controlled Power Function Motors

Version Three uses Four NXT Motor's. Three connected to the NXT Motor Ports, and the fourth is controlled via a Mindsensors NXT Motor Mux (NXTMMX). The NXTMMX's 'Sensor Daisy Cain Port' is used to control the NXTMMX and a single US. You just have too love the NXTMMX 's design.

Quad Drive Holomonic Platform Using NXT & NXTMMX Controlled NXT Motors




CAD of Quad Drive Holomonic Platform using NXT Motors & a NXTMMX




Notes Regarding the CAD Drawings:


The Red Wheels, in the CAD drawings need to be swapped for Rotacaster Omni-Wheels for the Robot to work.
The Bright Pink, 16-tooth Gears need to be replaced with 24-tooth Technic Gears. Due to the difficulty of aligning '24-tooth Technic Gears', I decided it would be less frustrating on my behalf just to use the Bright Pink 16-tooth Gears.


Download the LEGO Digital Designer CAD Files:

If you wish to use Multiple Ultrasonic Sensors on your NXT Robot, you need to program them so only ONE Sensor is taking a measurement at any given time. If you have all the Ultrasonic Sensors on at once, they interfere with each other and give incorrect readings. To get around this you need to take advantage of the Sensors 'Mode 3: Event Capture Mode':

Refer to the Lego Mindstorms NXT Hardware Developer Kit: Appendix 7: LEGO MINDSTORMS NXT Ultrasonic Sensor I2C communication protocol.pdf for details.



Event Capture Mode:


To use the Ultrasonic Sensor's "Mode 3" with NXC, you need to use I2CWrite(PORTnumber, 041, 003) to turn on and initialise the sensor. You can the then use SensorUS(PORTnumber) to read the distance to object. To turn the Sensor Off again, you need to use I2CWrite(PORTnumber, 041, 000).

You need to repeat these commands for each Ultrasonic Sensor you are using. It pays to initialise all your Ultrasonic Sensors to the Off state when the program starts.




As shown above, the Dual Drive, Quad Holomonic Platform is very flexible, allowing the use of Power Function Components, as well as the standard NXT Parts. If you only have four Rotacaster Omni-Wheels, the platform can be quickly modified to suite.

For full project details, including more information, video and Code examples: "www.rjmcnamara.com".


I was the instigator in bringing Rotacaster Omni-Wheels to the LEGO MINDSTORMS NXT Platform. Having been involved with Rotacaster Australia in their development stage, and then through to having available too everyone with a LEGO Technics or LEGO Mindstorms kit.




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By Sparra McNamara
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Added April 5, 2012
 

The background images used on this page are © Todd Lehman,
available at http://www.lugnet.com/fibblesnork/lego/backgrounds/


LEGO models my own creation MOCpages toys shop Dual Drive, Quad Holomonic PlatformRobotics


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