Projects | My One Wheel Board
THEME: LIGHT
OneWheelBoard

My One Wheel Board

Last Updated: 2020-11-10

Project Overview

I'm not a skateboarder, but I have decent balance and can lay down code. So instead of learning to ride someone else's board, I built my own.

I wanted to be able to adjust my ride on the fly without having to pair up my phone, so I added a simple settings interface and utilized the existing switches.

My gryo filter uses a simple principle for smooth and reliable angle measurement. As the accelerometer jumps around quite a bit while in motion, I factored it's parameter depending how far off it was from the current gyro reading. The further the accelerometer was from the gyro, the less I mixed into the current angle routine. I then averaged the total output over the last ten readings with a bias closer to zero.

The drive routine is simple. Multiply power by current angle, then compound additional power when desired angle is reached. This helps to keep the board within the desired operational angle.

The overdrive works by adding additional power over time while the desired angle is maintained. This allows the board to continue to reach higher speeds while maintaining a comfortable ride angle.

My board is utilizing a 48 volt, 800 watt hub motor and a VESC for the drive train. Powered by a 12s2p Samsung 18650 25R battery pack, I get a little over 10kms of range, a comfortable cruising speed of 20km/h, and a top speed of just over 35km/h.

The controller is an Arduino Nano V3 paired with an MPU6050.

Total firmware size is 15082 bytes (49%) of program storage & 1154 bytes (56%) of dynamic memory. Eeprom storage is 28 bytes.

The board is 30 inches long and 9.5 inches wide. The aluminum railes are 1 inch wide, 2 inches tall, 1/8 inch wall thickness and 28 inches long with a 45 degree cut on each end.

Operating the Board

Safety First

Wrap yourself in a thick mattress before stepping on this board...

But seriously, wear a helmet and a well fitting pair of flat souled shoes.

Gloves, elbow and knee pads are also a smart idea.

Powering Up The Board

On power up, you must first wait for the counter to reach 0 and display the battery voltage. This step is the software calibrating the gyro offset.

The board must be in a still position for this to take place. If the board senses any movement, the counter will reset to 10 and restart the calibration. This process takes place everytime you power on the board.

Arming the Board

To arm the board, you must first place the board at a greater than 10 degree angle with the back on the ground.

You then must step on the back button or foot sensor, followed by the front button or foot sensor. The display will now show 1111 and then quickly to 0. To engage the motor, you must tilt the board to the level position.

The board will now be armed and in operation.

You must be standing on atleast one of the two buttons or foot sensors to maintain operation of the board. Due to the wait of the board, the breaks will immediately engage when both buttons are released to prevent the board from being a powered projectile.

Settings Menu

To enter the settings menu, hold down the front button or foot sensor for atleast 5 seconds then release. The rear button or foot sensor must not be pressed for this procedure.

To cycle through the menu, press and release the front button or foot sensor.

To alter a setting, press and release the back button or foot sensor.

To reset a value to its lowest setting, hold the back button or foot sensor for atleast 3 seconds and release.

To exit the menu and save your settings, hold down the front button or foot sensor again for atleast 5 seconds. Your settings are now saved and you will be shown the voltage displays.

Setting #1 (Way Mode)

This setting determines whether the board move only forward or in both directions.

1001 = 1 way. The board will only move in the forward direction.
1002 = 2 way. The board will move in both directions.

I like to place the board in 1 way for long journeys, and in 2 way for playing around.

Setting #2 (Center Point) (Degrees * 10)

This allows the user to set a custom center point. Angle the board to the desired angle and press and release the rear foot button/pad.

I like to set about 2 degrees to the rear foot so that I am level while cruising and the nose is a little higher when climbing bumps.

Settings #3 (Center Zone) (Degrees)

This sets desired cruising angle.

My setting is 7 (3007).

Setting #4 (Angle Power) (Multiplier * 10)

This is the power to apply for angle.

My setting is 3.5 (4035).

Setting #5 (Angle Retain Power) (Multiplier * 10)

This is the power multiplied by each degree over the Center Zone. This is added to the Angle Power.

This should be set high enough to make it difficult to angle beyond the Center Zone, but not to high as to force the board to jerk back and forth.

My setting is 1.5 (5015).

Setting #6 (Overdrive Angle) (Degrees)

This is the angle to start applying over drive too.

My setting is 5 (6005).

Setting #7 (Overdrive Power) (Multiplier * 10 / 5 Seconds)

This is the value to start multiplying by each degree after Overdrive Angle.

This value should be set low enough that the board doesn't feel like it is kicking up when activated.

My Setting is 0.5 (7005).

Setting #8 (Overdrive Max) (Percent of Total Forward Throttle)

This is the maximum overdrive to add. This should not be set to high as to max out the forward throttle. If you max out the thottle, you will lose angle retention.

My setting is 30 (8030).

Setting #9 (Start Power) (Percent of Total Throttle * 10)

This is the initial power sent to the motor when past 0 in either direction.

Usually not needed for most motors, but lets say your motor required 2% power to start to turn under load, you would set a value of 2.0 (9020).

My setting is 0 (9000).

Setting #1 (Way Mode)

This setting determines whether the board move only forward or in both directions. I like to place the board in 1 way for long journeys, and in 2 way for playing around.

1001 = 1 way. The board will only move in the forward direction.
1002 = 2 way. The board will move in both directions.

Setting #2 (Max Power Mode) (Percent)

This setting determines how much of the 100% throttle to utilize in either direction.

Do not exceed 100 (2100)

Setting #3 (Center Zone) (Degrees)

This setting determines, in degrees, how far to tilt the board prior to utilizing the overdrive variable. This is your equal power to tilt zone.

I find a setting of 7 (3007) works best for me. The minimum setting is 5 as their has to be value less then the set value to allow the software to subtract incurred overdrive.

Setting #4 (Center Power) (Multiplied by 10)

This is the equal multiplier for standard power to angle ratio.

Ex: a setting of 30 (4030) will provide 3.0% duty to angle to drive the board. At 10 degrees of angle, the board will be attempting to drive the motor at 30% power.

Setting #5 (Overdrive Power) (Multiplied by 10)

This is the overdrive power variable. This will tell the board to add this value devided by 10 times how many degrees beyond the center zone to the overdrive variable.

Returning the board to an angle less than the center zone will subtract this value devided by 10 times how many degrees inside of the center zone from the overdrive variable.

The higher this setting, The more the board will feal like it is fighting you. This is by design as it naturally pushes the board to the center zone value. Holding the angle past the center zone will steadily increase the boards speed.

Be warned: The incurred overdrive value must be scrubbed before the board can be stopped in the level position. This is simply done by leaning back, but the more overdrive incurred the harder it will be to perform a sudden stop.

Personally I find 5 (5005) to be a good value for this setting.

Setting #6 (Start Power) (Percent) (Multiplied by 10)

This is the initial power sent to the motor when past 0 in either direction.

Usually not needed for most motors, but lets say your motor required 2% power to start to turn under load, you would set a value of 20 (6020).

Setting #7 (Kick Power) (Percent)

This is kick power in percent. This will cause the board to jump this value to the board once it reaches the Max Power Setting minus this value. This is designed to keep the board from traveling beyond the Max Power Setting.

Setting #8 (Factory Reset)

This is the factory reset settings. Hold the back button for atleast 3 secconds under this option to reset all values to their minimum values. The board will then save and exit the settings menu.

This setting is soon to be replaced by the set level option.

Specs & Hardware

Performance

  • Actual Range - 10 km
  • Top Speed - 36.7 km/h (Before I got to scared to go any faster.)
  • Full Charge from Empty - 3amp Charger - Between 2 and 2.5 hours.

Board Dimensions

    Outer Dimensions
  • 30 Inches Long
  • 9.5 Inches Wide
  • 0.5 Inches Thick
    Wheel Cut Out
  • 11 Inches long
  • 6.5 Inches Wide
  • Located at exact center. Due to the location of the tire on the axel,
    the tire will be slightly to the left side. As the tire valve
    is on the right side, this leaves enough clearence. If you ride
    Goofy Foot, you may want to mount the wheel in the opposite direction.
    Aluminum Rails
  • 28 Inches Long
  • 2 Inches Tall
  • 1 Inch Wide
  • 1/8 Inch Wall Thickness
  • 45 Degree Cut on Each End.

Hardware

  • Battery - 12s2p (24 Sansung 18650 25R Cells (Green Batteries)) - Here
  • Hub Motor - 10x6inch 48v 800w (From AliExpress) - Here
  • ESC - Maytech VESC - Here
  • Controller - Arduino Nano V3 - Here
  • Display - TM1637 - Here
  • Gyro - MPU6050 - Here
  • BMS - Deligreen 12s 36v 50amp (Used for Charge Only) - Here
  • Foot Buttons - 16mm Reset screw + High Round - Here
  • Charge Port - 5.5x2.1mm - Here
  • Charger - DC 5.5x2.1 - Here
  • Anti-spark Switch - Maytech MTS1810AS - Here

Pending...

Wiring

My setup utilizes 2 waterproof momentary switches mounted flush to act as the front and rear safety/settings switches. These switches are wired in pull-up configuration. I also utilize a Piezo Buzzer and a TM1637 display module.

Button One (Back Foot Button)

Utilizing a 4k7 resistor I bridge digital pin 6 to 5 volt positive, then wire the switch from pin 6 to ground when pressed.

Button Two (Front Foot Button)

Utilizing a 4k7 resistor I bridge digital pin 7 to 5 volt positive, then wire the switch from pin 7 to ground when pressed.

Piezo Buzzer

The buzzer I wire positive to digital pin 10 and negative to ground.

TM1637 Display

I wire VIN to 5 volt positive, GND to ground, CLK to digital pin 4, and DIO to digital pin 3.

MPU6050 Module

VCC to 5 volt positive, GND to ground, SCL to A5 (SCL), SDA to A4 (SDA).


More Pending...

Arduino Nano Code

Note: disconnect UART cable from VESC before programming Arduino, even if VESC is powered off.

Use these versions of the required libraries. Some have been modified to work better with the Arduino Nano.

Version 1.11 now released.

This new version is now smoother and has a couple of new settings available.

Note: Upgrading to this version will erase your current settings.

BoardApp1-11.ino
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MPU6050x.ino
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TM1637Display.cpp
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TM1637Display.h
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VescUart.cpp
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VescUart.h
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buffer.cpp
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buffer.h
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crc.cpp
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crc.h
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datatypes.h
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3D Prints

Rail Ends

Best printed with TPU, this part doubles to protect the aluminum rail ends and for breaking.

Download

Pending...

VESC Setup (Pending)

This is coming soon, sorry.

Side Projects


Base Code For Micro Projects (No Display, One Arm Switch/Pad)

This is Firmware Version 1.11 cut down for smaller projects.

The board will beep when the Gyro is calibrated and beep again when Armed. During operation, the board will beep when 85% of max speed is reached in either direction.

Requires a piezo buzzer. (The one found in most PCs or are provided with new computer cases.)

Adjust your settings at the top of the code. Add your drive routine near the bottom inside the motorRoutine routine.

Download


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