hoverboard-firmware-hack-FOC

This repository implements Field Oriented Control (FOC) for stock hoverboards. Compared to the commutation method, this new FOC control method offers superior performance featuring:

• reduced noise and vibrations
• smooth torque output and improved motor efficiency. Thus, lower energy consumption
• field weakening to increase maximum speed range

Table of Contents

• Hardware
• FOC Firmware
• Example Variants
• Dual Inputs
• Flashing
• Troubleshooting
• Diagnostics
• Projects and Links
• Contributions

For the hoverboard sideboard firmware, see the following repositories:

• hoverboard-sideboard-hack-GD
• hoverboard-sideboard-hack-STM

For the FOC controller design, see the following repository:

• bldc-motor-control-FOC

Videos:

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Hardware

The original Hardware supports two 4-pin cables that originally were connected to the two sideboards. They break out GND, 12/15V and USART2&3 of the Hoverboard mainboard. Both USART2&3 support UART, PWM, PPM, and iBUS input. Additionally, the USART2 can be used as 12bit ADC, while USART3 can be used for I2C. Note that while USART3 (right sideboard cable) is 5V tolerant, USART2 (left sideboard cable) is not 5V tolerant.

Typically, the mainboard brain is an STM32F103RCT6, however some mainboards feature a GD32F103RCT6 which is also supported by this firmware.

For the reverse-engineered schematics of the mainboard, see 20150722_hoverboard_sch.pdf

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FOC Firmware

In this firmware 3 control types are available:

• Commutation
• SIN (Sinusoidal)
• FOC (Field Oriented Control) with the following 3 control modes:
  • VOLTAGE MODE: in this mode the controller applies a constant Voltage to the motors. Recommended for robotics applications or applications where a fast motor response is required.
  • SPEED MODE: in this mode a closed-loop controller realizes the input speed target by rejecting any of the disturbance (resistive load) applied to the motor. Recommended for robotics applications or constant speed applications.
  • TORQUE MODE: in this mode the input torque target is realized. This mode enables motor "freewheeling" when the torque target is 0. Recommended for most applications with a sitting human driver.

Comparison between different control methods

Control method	Complexity	Efficiency	Smoothness	Field Weakening	Freewheeling	Standstill hold
Commutation	-	-	++	n.a.	n.a.	+
Sinusoidal	+	++	++	+++	n.a.	+
FOC VOLTAGE	++	+++	++	++	n.a.	+(2)
FOC SPEED	+++	+++	+	++	n.a.	+++
FOC TORQUE	+++	+++	+++	++	+++(1)	n.a(2)

⁽¹⁾ By enabling ELECTRIC_BRAKE_ENABLE in config.h, the freewheeling amount can be adjusted using the ELECTRIC_BRAKE_MAX parameter.
⁽²⁾ The standstill hold functionality can be forced by enabling STANDSTILL_HOLD_ENABLE in config.h.

In all FOC control modes, the controller features maximum motor speed and maximum motor current protection. This brings great advantages to fulfil the needs of many robotic applications while maintaining safe operation.

Field Weakening / Phase Advance

• By default the Field weakening is disabled. You can enable it in config.h file by setting the FIELD_WEAK_ENA = 1
• The Field Weakening is a linear interpolation from 0 to FIELD_WEAK_MAX or PHASE_ADV_MAX (depeding if FOC or SIN is selected, respectively)
• The Field Weakening starts engaging at FIELD_WEAK_LO and reaches the maximum value at FIELD_WEAK_HI
• The figure below shows different possible calibrations for Field Weakening / Phase Advance
• If you re-calibrate the Field Weakening please take all the safety measures! The motors can spin very fast!

Parameters

• All the calibratable motor parameters can be found in the 'BLDC_controller_data.c'. I provided you with an already calibrated controller, but if you feel like fine tuning it feel free to do so
• The parameters are represented in Fixed-point data type for a more efficient code execution
• For calibrating the fixed-point parameters use the Fixed-Point Viewer tool
• The controller parameters are given in this table

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Example Variants

This firmware offers currently these variants (selectable in platformio.ini or config.h):

• VARIANT_ADC: The motors are controlled by two potentiometers connected to the Left sensor cable (long wired)
• VARIANT_USART: The motors are controlled via serial protocol (e.g. on USART3 right sensor cable, the short wired cable). The commands can be sent from an Arduino. Check out the hoverserial.ino as an example sketch.
• VARIANT_NUNCHUK: Wii Nunchuk offers one hand control for throttle, braking and steering. This was one of the first input device used for electric armchairs or bottle crates.
• VARIANT_PPM: RC remote control with PPM Sum signal.
• VARIANT_PWM: RC remote control with PWM signal.
• VARIANT_IBUS: RC remote control with Flysky iBUS protocol connected to the Left sensor cable.
• VARIANT_HOVERCAR: The motors are controlled by two pedals brake and throttle. Reverse is engaged by double tapping on the brake pedal at standstill. See HOVERCAR video.
• VARIANT_HOVERBOARD: The mainboard reads the two sideboards data. The sideboards need to be flashed with the hacked version. The balancing controller is not yet implemented.
• VARIANT_TRANSPOTTER: This is for transpotter build, which is a hoverboard based transportation system. For more details on how to build it check here and here.
• VARIANT_SKATEBOARD: This is for skateboard build, controlled using an RC remote with PWM signal connected to the right sensor cable.

Of course the firmware can be further customized for other needs or projects.

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Dual Inputs

The firmware supports the input to be provided from two different sources connected to the Left and Right cable, respectively. To enable dual-inputs functionality uncomment #define DUAL_INPUTS in config.h for the respective variant. Various dual-inputs combinations can be realized as illustrated in the following table:

Left	Right	Availability
ADC(0)	UART(1)	VARIANT_ADC
ADC(0)	{PPM,PWM,iBUS}(1)	VARIANT_{PPM,PWM,IBUS}
ADC(0)	Sideboard(1*)	VARIANT_HOVERCAR
UART(0)	Sideboard(1*)	VARIANT_UART
UART(1)	Nunchuk(0)	VARIANT_NUNCHUK

⁽⁰⁾ Primary input: this input is used when the Auxilliary input is not available or not connected.
⁽¹⁾ Auxilliary input: this inputs is used when connected or enabled by a switch^(*). If the Auxilliary input is disconnected, the firmware will automatically switch to the Primary input. Timeout is reported only on the Primary input.

With slight modifications in config.h, other dual-inputs combinations can be realized as:

Left	Right	Possibility
Sideboard(1*)	UART(0)	VARIANT_UART
UART(0)	{PPM,PWM,iBUS}(1)	VARIANT_{PPM,PWM,IBUS}
{PPM,PWM,iBUS}(1)	Nunchuk(0)	VARIANT_{PPM,PWM,IBUS}

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Flashing

Right to the STM32, there is a debugging header with GND, 3V3, SWDIO and SWCLK. Connect GND, SWDIO and SWCLK to your SWD programmer, like the ST-Link found on many STM devboards.

If you have never flashed your sideboard before, the MCU is probably locked. To unlock the flash, check-out the wiki page How to Unlock MCU flash.

Do not power the mainboard from the 3.3V of your programmer! This has already killed multiple mainboards.

Make sure you hold the powerbutton or connect a jumper to the power button pins while flashing the firmware, as the STM might release the power latch and switches itself off during flashing. Battery > 36V have to be connected while flashing.

To build and flash choose one of the following methods:

Method 1: Using Platformio IDE

• open the folder in the IDE of choice (vscode or Atom)
• press the 'PlatformIO:Build' or the 'PlatformIO:Upload' button (bottom left in vscode).

Method 2: Using Keil uVision

• in Keil uVision, open the mainboard-hack.uvproj
• if you are asked to install missing packages, click Yes
• click Build Target (or press F7) to build the firmware
• click Load Code (or press F8) to flash the firmware.

Method 3: Using Linux CLI

• prerequisites: install ST-Flash utility.
• open a terminal in the repo check-out folder and if you have definded the variant in config.h type:

make

or you can set the variant like this

make -e VARIANT=VARIANT_####

• flash the firmware by typing:

make flash

• or

openocd -f interface/stlink-v2.cfg -f target/stm32f1x.cfg -c flash "write_image erase build/hover.bin 0x8000000"

Method 4: MacOS CLI

• prerequisites: first get brew https://brew.sh
• then install stlink ST-Flash utility

Using Make

brew install stlink

• open a terminal in the repo check-out folder and if you have definded the variant in config.h type:

make

or you can set the variant like this

make -e VARIANT=VARIANT_####

If compiling fails because something is missing just install it with brew AND leave a comment to improve this howto or pull request ;-)

• flash the firmware by typing:

make flash

• if unlock is needed

make unlock

Using platformio CLI

brew install platformio
platformio run -e VARIANT_####
platformio run –target upload -e VARIANT_####

If you have set default_envs in platformio.ini you can ommit -e parameter

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Troubleshooting

First, check that power is connected and voltage is >36V while flashing. If the board draws more than 100mA in idle, it's probably broken.

If the motors do something, but don't rotate smooth and quietly, try to use an alternative phase mapping. Usually, color-correct mapping (blue to blue, green to green, yellow to yellow) works fine. However, some hoverboards have a different layout then others, and this might be the reason your motor isn't spinning.

Nunchuk not working: Use the right one of the 2 types of nunchuks. Use i2c pullups.

Nunchuk or PPM working bad: The i2c bus and PPM signal are very sensitive to emv distortions of the motor controller. They get stronger the faster you are. Keep cables short, use shielded cable, use ferrits, stabilize voltage in nunchuk or reviever, add i2c pullups. To many errors leads to very high accelerations which triggers the protection board within the battery to shut everything down.

Recommendation: Nunchuk Breakout Board https://github.com/Jan--Henrik/hoverboard-breakout

Most robust way for input is to use the ADC and potis. It works well even on 1m unshielded cable. Solder ~100k Ohm resistors between ADC-inputs and gnd directly on the mainboard. Use potis as pullups to 3.3V.

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Diagnostics

The errors reported by the board are in the form of audible beeps:

• 1 beep (low pitch): Motor error (see possible causes)
• 2 beeps (low pitch): ADC timeout
• 3 beeps (low pitch): Serial communication timeout
• 4 beeps (low pitch): General timeout (PPM, PWM, Nunchuk)
• 5 beeps (low pitch): Mainboard temperature warning
• 1 beep slow (medium pitch): Low battery voltage < 36V
• 1 beep fast (medium pitch): Low battery voltage < 35V
• 1 beep fast (high pitch): Backward spinning motors

For a more detailed troubleshooting connect an FTDI Serial adapter or a Bluetooth module to the DEBUG_SERIAL cable (Left or Right) and monitor the output data using the Hoverboard Web Serial Control tool developed by Candas.

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Projects and Links

• Original firmware: https://github.com/NiklasFauth/hoverboard-firmware-hack
• Candas Hoverboard Web Serial Control: https://candas1.github.io/Hoverboard-Web-Serial-Control/
• RoboDurden's online compiler: https://pionierland.de/hoverhack/
• Hoverboard hack for AT32F403RCT6 mainboards: https://github.com/cloidnerux/hoverboard-firmware-hack
• Hoverboard hack for split mainboards: https://github.com/flo199213/Hoverboard-Firmware-Hack-Gen2
• Hoverboard hack from BiPropellant: https://github.com/bipropellant
• Hoverboard breakout boards: https://github.com/Jan--Henrik/hoverboard-breakout

• Bobbycar https://github.com/larsmm/hoverboard-firmware-hack-bbcar
• Wheel chair: https://github.com/Lahorde/steer_speed_ctrl
• TranspOtterNG: https://github.com/Jan--Henrik/transpOtterNG
• ST Community: Custom FOC motor control

• Telegram Community: If you are an enthusiast join our Hooover Telegram Group

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Contributions

Every contribution to this repository is highly appreciated! Feel free to create pull requests to improve this firmware as ultimately you are going to help everyone.

If you want to donate to keep this firmware updated, please use the link below:

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