This section outlines the steps required to build a mecanum drivetrain using the Mecanum Drivetrain Kit V2 (REV-45-2470). The Mecanum Drivetrain Kit V2 uses UltraPlanetary Gearboxes and Ultra 90 Degree Gearboxes for a direct drive rather than one driven with belts or chain. For instructions on how to build a mecanum drivetrain with belts and pulleys check out the Mecanum Drivetrain Kit or for a mecanum drivetrain with sprockets and chain see the Channel Drivetrain - Mecanum Upgrade.
This design is a great starting point. However, modification may be required to address the specific needs of the robot being designed.
The assembly of this drivetrain can be broken into a few sections. This allows for a team of people to work on different tasks to complete the build quicker. Each Section Begins with what parts and the quantity of parts needed to complete the steps in that section. A list of all required materials for the drivetrain is listed below.
This drivetrain can be built out of the following kit:
The Ultra 90 Degree Gearbox should have 4mm of thread engagement with each screw. If you do not have 6mm screws to use for your assembly, please use washers or a spacer of approximately 2mm thickness on the outside of the C Channel.
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| Part Number | Description | QTY Included in Kit |
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Mecanum Drivetrain Kit V2
1
15mm Plastic 90 Degree Bracket - 8 Pack
1
15mm Spacer - 12 Pack
1
3mm Spacer - 16 Pack
1
Shaft Collars - 10 Pack
1
5mm x 90mm Hex Shaft - 4 Pack
1
M3 x 8mm Hex Cap Screws - 100 Pack
1
M3 x 6mm Hex Cap Screws - 100 Pack
1
M3 Nyloc Nuts - 100 Pack
1
UltraPlanetary Gearbox Kit & HD Hex Motor
4
45mm x 15mm C Channel - 408mm
4
45mm x 15mm C Channel - 248mm
2
75mm Mecanum Wheel Set
1
Ultra 90 Degree Gearbox
4
2mm Allen Wrench
1
1.5mm Allen Wrench
1
5.5mm Combination Wrench
1
5.5mm Nut Driver
1
PART NUMBER | DESCRIPTION | QTY. |
UltraPlanetary Gearbox, Assembled with 20:1 Ratio | 4 |
Ultra 90 Degree Gearbox | 4 |
REV-41-2081 | 5mm Hex Shaft, 20mm | 4 |
REV-41-2082 | UltraPlanetary Face Mount Spacer | 4 |
M3 x 40mm Socket Head Cap Screw | 16 |
Insert the 20mm long hex shaft into the output of the gearbox. |
Place the Face Mount Spacer on the output of the the gearbox as shown. Note: Line up the short edge of the spacer with a flat side of the UltraPlanetary gearbox body. |
Rotate the hex shaft output so that it lines up with the hex input on the Ultra 90 Degree Gearbox. |
Slide the two gearboxes together. Rotate the Ultra 90 Degree Gearbox until the spacer and gearbox body line up. |
Insert the 4 mounting screws in the holes on the end of the Ultra 90 Degree Gearbox. Ensure that they line up with the holes in the spacer and the gearbox. |
Tighten the 4 mounting screws hand-tight. Then alternate between slightly tightening screws diagonally across from each other in an X shaped pattern. Note: Take care not to over tighten the mounting screws. |
15mm Plastic 90 Degree Bracket - 8 Pack | 1 |
15mm Spacer - 12 Pack | 1 |
3mm Spacer - 16 Pack | 1 |
Shaft Collars - 10 Pack | 1 |
5mm x 90mm Hex Shaft - 4 Pack | 1 |
M3 x 8mm Hex Cap Screws - 100 Pack | 1 |
M3 x 6mm Hex Cap Screws - 50 Pack | 1 |
M3 Nyloc Nuts - 100 Pack | 1 |
45mm x 15mm C Channel - 408mm | 4 |
75mm Mecanum Wheel Set | 1 |
Mount a Universal Hex Adapter to each Mecanum wheel using 4 - M3 8mm Screws After completing this step you will have 4 assembled mecanum wheels. |
Slide the following onto a 90mm long 5mm Hex Shaft. Make 2 of the Right Wheel Shaft assembly - 3mm Spacer (Or 2 - 1.5mm Spacers) -15mm Spacer -Right 75mm Mecanum Wheel -Shaft Collar The Shaft Collar should be flush with the right side of the Hex Shaft. |
Slide the following onto a 90mm long 5mm Hex Shaft. Make 2 of the Left Wheel Shaft assembly - 3mm Spacer (Or 2 - 1.5mm Spacers) -15mm Spacer -Left 75mm Mecanum Wheel -Shaft Collar The Shaft Collar should be flush with the right side of the Hex Shaft. |
Fasten 2 Motor Pod Assemblies with 16 - M3 6mm Hex Head Screws total in between two pieces of C Channel The output of the Ultra 90 Degree Gearbox will line up with the 2nd large (9mm) hole from each end of the C Channel |
Fasten 4 - Plastic 90 Degree Brackets to the top and bottom of the back side of the C Channel facing inwards as shown in the image. Load the brackets fully with 5 - M3 8mm Hex Cap Screws and 5 - M3 Nyloc Nuts each. |
Insert the Left Wheel Shaft Assembly into the Ultra 90 Degree Gearbox that is closest to the plastic brackets. Insert the Right Wheel Shaft Assembly into the Ultra 90 Degree Gearbox that is at the front of the drive rail Secure both Wheel Shafts with a Shaft Collar |
Fasten 4 - Plastic 90 Degree Brackets to the top and bottom of the back side of the C Channel facing inwards as shown in the image. Load the brackets fully with 5 - M3 8mm Hex Cap Screws and 5 - M3 Nyloc Nuts each. |
Insert the Right Wheel Shaft Assembly into the Ultra 90 Degree Gearbox that is closest to the plastic brackets. Insert the Left Wheel Shaft Assembly into the Ultra 90 Degree Gearbox that is at the front of the drive rail Secure both Wheel Shafts with a Shaft Collar |
Make sure the Mecanum Wheels form an "X" shape when they have been fastened to the Drive Rails |
The Mecanum Drivetrain Kit V2 comes with four of the UltraPlanetary Gearbox Kits with HD Hex Motors. This is an entry point into using the REV UltraPlanetary System. There are three UltraPlanetary Cartridges supporting seven different final gear reductions ranging from nominally 3:1 to 60:1. This allows for the right amount of torque for the application at hand. The motor provided already has the pinion gear pressed onto it making assembly of gearboxes easier.
When getting started with this drivetrain, it is recommended to use a nominal 20:1 Gear Ratio. This uses the UltraPlanetary 5:1 Cartridge and the UltraPlanetary 4:1 Cartridge. For more information on all gear ratio options, load ratings, and more, see the UltraPlanetary Gearbox User’s Manual.
Repeat these steps until you have four fully assembled gearboxes.
Each side of the chassis needs one left and one right wheel. Mecanum Chassis also require four motors for operation.‌
To know if your Mecanum Wheels are properly configured look from the top down on the drivetrain. Following diagonal lines created from the angle of the rollers should form an "X" as shown above.‌
Running all four wheels in the same direction at the same speed will result in a forward/backward movement, as the longitudinal force vectors add up but the transverse vectors cancel each other out, as shown below.‌
When both wheels on one side of the drivetrain are moving in one direction while the other side is moving in the opposite direction results in stationary rotation of the drivetrain. The transverse vectors cancel out but the longitudinal vectors combine to generate rotation around the central vertical axis of the drivetrain, as shown below.‌
When the right mecanum wheels run in one direction while the left mecanum wheels run in the opposite direction allows for a strafing movement, as the transverse vectors add up but the longitudinal vectors cancel out.‌
Using the above concepts in tandem through varying motor power to each wheel type allows for the drivetrain to move in different, angled vectors.
Before getting started with programming we needed to create a configuration file. Below is an overview of how the robot is configured for the teleop code to function as expected:
To put this configuration file on your robot, drag this file into the "FIRST" folder of your Control Hub's file system.
Full code:
For this program, when it is first initialized the lefthand motors will be set to run in reverse.
For a mecanum drivetrain all 4 motors will be given a command to follow when the left joystick is moved forward/back.
For this example, strafing is controlled by the right stick's X-axis allowing the robot to slide left and right as the diagnol wheels move in opposite directions.
For this demo, turning is controlled by moving the left stick back and forth along it's X-axis.
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Mecanum wheels, when properly set up on a drivetrain, allow for omni-directional movement. Each Mecanum Wheel Set () comes with a two right (REV-41-1656) and two left (REV-41-1657) mecanum wheels. This is determined by the direction of the leading edge of the rollers. If the rollers point left it is a left wheel and if they point right it is a right wheel.
Need help programming your mecanum drivetrain? Check out our page!
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For more in-depth information on the configuration process check out !
| Gamepad Input | Function |
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More information on programming gamepads for use with your robot can be found at.
This section makes the assumption that you have learned some of the FTC programming basics by going through the guide. If you have not gone through this guide please walk through it before proceeding.
In we covered how to program arcade drive with one joystick. For this example, we will be programming arcade drive using two joysticks to allow for strafing on the right stick. Remember this is just one way mecanum can be programmed!
45mm x 15mm C Channel - 248mm
2
PART NUMBER
DESCRIPTION
QTY.
HD HEX MOTOR
1
ULTRAPLANETARY PINION GEAR (ON HD HEX MOTOR)
1
ULTRAPLANETARY MOUNTING PLATE
1
ULTRAPLANETARY CARTRIDGE 4:1
1
ULTRAPLANETARY CARTRIDGE 5:1
1
ULTRAPLANETARY OUTPUT STAGE
1
M3 X 30MM CAP HEAD SCREW
6
M3 X 8MM BUTTON HEAD SCREW
2
Motor | 0 | REV Robotics Ultraplanetary HD Hex Motor | frontLeft |
Motor | 1 | REV Robotics Ultraplanetary HD Hex Motor | frontRight |
Motor | 2 | REV Robotics Ultraplanetary HD Hex Motor | backLeft |
Motor | 3 | REV Robotics Ultraplanetary HD Hex Motor | backRight |
Right Joystick - Left/Right | Strafe Left/Right |
Left Joystick - Forward/Backward | Forward/Backward |
Left Joystick - Left/Right | Turn Counter-Clockwise/Clockwise |
Slide the Left and Right Drive Rail on each side of 2 pieces of 248mm C Channel
Tighten the Nyloc Nuts on each bracket to secure your drivetrain
Attach the UltraPlanetary Mounting Plate to the HD Hex Motor using two 8mm Button Head Screws.
Note: Use the 2mm Allen Key to tighten these screws.
Seat the UltraPlanetary 5:1 Cartridge onto the input pinon.
Note: Placing a finger on the output of the 5:1 Cartridge and turning it helps for placement.
Seat the UltraPlanetary 4:1 Cartridge onto the UltraPlanetary 5:1 Cartridge.
Note: Placing a finger on the output of the 4:1 Cartridge and turning it helps for placement.
Seat the UltraPlanetary Output Stage onto the UltraPlanetary 4:1 Cartridge.
Note: Placing a finger on the output of the Output Cartridge and turning it helps for placement.
Insert six of the 30mm Cap Head Screws into the holes in the outer ring off the Output Cartridge.
Tighten these screws down until they are snug not tight using a 2.5mm allen wrench.
Note: The 30mm length is the 2nd longest screw provided with the UltraPlanetary Gearbox Kit.