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MagBot Model 2
VEX Magnetic Climbing Robot

This is the second prototype of the VEX Magnetic Climbing Robot Model 2.  It was determined that magnetized tracks provide better adhesion to the climbing face than the passive wheels that were used in Model 1.  The tracks also provide a high degree of maneuverability that was not present in Model 1.

Magbot 2 uses (44) Neodymium Rare Earth Magnets per track.  The magnets themselves are attached by using heat shrink.  The rubberized heat shrink also provided additional traction and protected the magnets themselves from minor damage. 

Great care was taken to keep Model 2 as light and as simple as possible.  The VEX Signal Splitter as well as the Radio Receiver were used as structural members of the frame.  The frame members themselves are all aluminum.  This kept the total weight of the robot including the battery to only 907g.

The initial design of Model 2 placed the battery and a camera on top of the chassis.  This proved to be a poor design due to the high Center of Gravity.  The high CG led to the robots inability to climb vertically.  It could however traverse the climbing face horizontally.  The camera was removed and the battery was moved below the chassis.  This corrected the high CG and led to the ability to vertically ascend the climbing face.

The magnetized tracks provided a significant advantage over the passive wheel design.  The tracks require additional maintenance to ensure the heat shrink is holding the magnets firmly to the track itself.  This could be corrected with adhesive, however due to the Gravitationally Induced Damage (GID) the magnets had to be recycled to new sections of track.  Adhesives would initially prove advantageous but prevent the magnets from being easily removed during track repair.

The Model 2 exhibited several performance enhancements over Model 1.  The high degree of maneuverability being the most important.  Model 2 is able to transition between the ground and the climbing face with relative ease.  The robot is more prone to GID due to the operator pushing the performance limits of the magnetized track.  Model 2 has met all the original design goals.  Initial transitions from vertical climbing to hanging maneuverability, (from the wall to the ceiling) have not been successful, however additional modifications and testing will continue.


Built and Designed by: Beener  See the Original Model 1 and the next Model 3


Magbot Technical Specifications

Robot Technical Specifications

Chassis Aluminum
Weight 2.0lbs (907g)
Dimensions (L x W x H) 8" x 6.75" x 1.75" - 3.75" with motors (203.2mm x 171.5mm x 44.5mm - 95.2mm)
Tracks VEX Tank Tread Upgrade Kit
(44) Magnets per Track
Motors (2) VEX Continuous Rotation Motors
Electronics (1) VEX Signal Splitter
(1) RF Receiver Module
Drivetrain Direct drive through bevel gears
1:1 gear ratio
Torque 13 in/lb @ 100 rpm (1.45 m/kg)
Min/Max Voltage 4.4 - 15 Volts

Magnet Technical Specifications

Magnets (88) Neodymium Rare Earth Magnets
Dimensions 12mm long
6mm wide
1.5mm thick
Plating Nickel
Surface Gauss 1950
Magnetized through 1.5mm thickness
Coercivity 12410 Gauss
Remanance 12.21 kOe
Max Energy Product 38.09 MGOe
Pull Strength 2.72kg (6lbs)
Weight 0.85g (0.03oz)
The magnets were purchased from Gaussboys.  They were the cheapest place I could find for Rare Earth Magnets.
I also called them up and they provided excellent technical support on determining which magnets would be best for this application.

Magbot Photos


Click on image to Enlarge

VEX Magnetic Climbing Robot
Notice the alternating magnetized track.  This provided more than adequate adhesion.
VEX Magnetic Climbing Robot
The shrink wrap works best by covering as much of the magnet as possible.
VEX Magnetic Climbing Robot
The track upgrade kit has rubberized sections that give it additional traction over the standard track.  Notice how good the profile of the track is.
 
VEX Magnetic Climbing Robot
The batter placement limits the ground clearance of the robot.  Having the battery on top provides good ground clearance but creates a high CG and the robot won't climb straight up.
VEX Magnetic Climbing Robot
Every that could be stuffed under the robot was located there.  This also provides adequate protection from GID.
VEX Magnetic Climbing Robot
Notice how the Electronics are used as structural components of the chassis.  During testing the electronics did not suffer from any GID.
VEX Magnetic Climbing Robot
The top mounted motors are exposed and subject to GID.  Using the electronics as structural components limited the space to mount the motors.
VEX Magnetic Climbing Robot
Model 2 was kept as simple as possible.  This provided for easy maintenance and repairs. 


YouTube Videos - Successes and Failures
Additional Videos - InnovationFirst Channel
 


Maneuverability Demonstration
Top Camera View
 
Maneuverability Demonstration
Front Camera View

Gravity Demonstration
Top Camera View

Magnetic Release Demonstration
Top Camera View