Magbot Model 3

From VEX Wiki

The VEX Magnetic Climbing Robot Model 3 was designed to maneuver across different climbing faces such as: from a horizontal face to a vertical face. In order to achieve this type of maneuver the frame needed to be very flexible. This was accomplished by numerous pivot points along the frame. Previous models were only able to maneuver from the ground to the climbing surface and were not able to perform any of the advanced maneuvers.

The Model 3 is designed with four independent magnetic tracks. The Model 2 demonstrated the advantage to using magnetic track over the passive wheel design used in Model 1. Each of the magnetic tracks has 270° of rotation. The chassis itself has 200° of rotation at the end pivots and 100° at the center pivot. This allows the robot to maintain at least three points of contact at all times while maneuvering between climbing faces.

The Model 3 was able to successfully perform all the maneuvers that it was originally designed for. There is possible improvements that could be gained with additional frame modifications. This design has a higher center of gravity than Model 2. The battery was responsible for most of the weight. Model 2 had the battery mounted under the frame and was almost dragging the ground. Additional improvements would be gained by using a VEX MicroController instead of the simple Signal Splitter. This would allow mechanization of all the track pivots as well as the fine control that was not possible with the Signal Splitter. However this would also increase the weight and complexity of the robot itself. This was one of the key factors in determining when to cease working on improving the overall design of Model 3. Additional work could have been done with only marginal increases in performance. The design of this robot has gone about as far as it could go.

Robot Technical Specifications
Chassis	Aluminum
Weight	4.8lbs (2177g)
Dimensions (L x W x H)	18" x 7.25" x 5.75" (457mm x 184mm x 146mm)
Tracks	Vex Tank Tread Upgrade Kit (78) Magnets per Front Track (156) total small magnets. (20) Magnets per Rear Track (40) total large magnets.
Motors	(6) Vex Continuous Rotation Motors (4) Drive Motors (2) Motors to control front track positioning
Electronics	(1) Vex Signal Splitter (1) RF Receiver Module
Drivetrain	Direct Drive through 36 tooth 1.5" gears 1:1 gear ratio
Torque	7.5in/lb @ 100 rpm (1.45 m/kg)
Min/Max Voltage	4.4 - 15 Volts

Magnet Technical Specifications
Magnets	(156) Small Neodymium Rare Earth Magnets (40) Large Neodymium Rare Earth Magnets
Dimensions	Small Magnets 12mm long 6mm wide 1.5mm thick	Large Magnets 25mm long 6mm wide 3mm thick
Plating	Nickel	Nickel
Surface Gauss	1950	3100
Magnetized	through 1.5mm thickness	through 3mm thickness
Coercivity	12410 Gauss	12090 Gauss
Remanance	12.21kOe	11.69 kOe
Max Energy Product	38.09 MGOe	35.32 MGOe
Pull Strength	2.72kg (6lbs)	5.89kg (13lbs)
Weight	0.85g (0.03oz)	6.52g (0.23oz)
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.