Magbot Model 2

From VEX Wiki

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 Model1. 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.

Robot Technical Specifications
Chassis	Aluminum
Weight	2.0lbs (907g)
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 @ 100rpm (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)