S20 ability to run without out a hall sensor

[Resko727]

I haven’t seen anyone mention this and I believe this a step in right direction to remove a potential weakness in eucs designs. I would like to hear more about this and wonder how it works in reality. I admire KingSong move in the right direction where saftey is big part of design.

[rcgldr]

The would still need to be some form of torque sensing in order for an EUC to maintain balance. I don't know what they are using instead of hall sensors.

 

[Planemo]

It uses Hall to establish the initial movement from rest, then switches over to reading the back emf from the motor to establish rotor position once underway.

So any hall sensor/wiring failure when riding is is a non issue, its only when you come to a total stop the wheel would lose balance and presumably an audible warning/alert to the rider.

Its a step in the right direction, but I am not aware of any great numbers of hall sensor failures. That said, if the new system saves just one crash, its a bonus.

[RagingGrandpa]

2 hours ago, Resko727 said:

I haven’t seen anyone mention this

It's rare.

https://forum.electricunicycle.org/topic/18012-hall-sensor-disconnected-while-riding-faceplant/

It may become more relevant as these new sprung-chassis suspension wheels age, and their constantly flexing motor cables deteriorate... but in my experience, thick conductors crack and fail faster than thin ones when exposed to the same flexing cycle, so it may be that you'll lose the motor phase wires before the position sensor wires

 

Edited September 30, 2021 by RagingGrandpa

[enaon]

I think sensor reading failures are more common than we believe. It is not like a cable must come loose, nor the sensors have to fail all together. False reading can happen, and they can lead to failure. Ninebot's black box was very useful for observing this, I could see hall sensors reading fail warnings quite often when I was pushing the Wheel to the limits. 

Edited September 30, 2021 by enaon

[RayRay]

22 hours ago, RagingGrandpa said:

It may become more relevant as these new sprung-chassis suspension wheels age, and their constantly flexing motor cables deteriorate

Is this wire constantly flexing with the suspension? (Yikes!) 

[Kekafuch]

Possible application being used here by Kingsong. 

 

High Frequency Injection

 

 

[mike_bike_kite]

This is probably a stupid question but aren't hall effect sensors used to detect magnetic change? What do they do in an EUC? I thought EUCs used accelerometers to detect how the wheel was orientated. I'm a bit confused (most of the time actually).

[Tawpie]

Hall effect sensors are used to identify where the wheel is in its rotation, which allows the controller to time the application of current to the motor electromagnets. They work by detecting how close a magnet is to the sensor and send that 'distance' as a voltage to the controller. When the motor is turning, these look like pulses. By looking at the timing and phase (rising or falling voltage) relationships between the pulses received from each of the sensors you can tell where the motor's magnets are in relationship to the coils AND you can tell the direction and speed at which the motor is turning.

The accelerometers' primary function is to determine how far from 'upright' the wheel is, and apply more or less force in the appropriate direction to try to maintain the upright position. Sometimes people say that gyroscopes are used for balancing an EUC but I don't think that's exactly what's happening—in practice it's done more simply with accelerometers. Precision gyroscopes are expensive and fragile and suffer from drift, so while the concept is sort of correct, a real gyroscope probably wouldn't work very well at all.

Edited October 1, 2021 by Tawpie

[Planemo]

47 minutes ago, Tawpie said:

Sometimes people say that gyroscopes are used for balancing an EUC but I don't think that's exactly what's happening—in practice it's done more simply with accelerometers. Precision gyroscopes are expensive and fragile and suffer from drift, so while the concept is sort of correct, a real gyroscope probably wouldn't work very well at all.

You did a pretty good job of explaining the hall sensors job 

For the accelerometer/gyro argument, I would say euc's use gyros. Only because, in my view, accelerometers by definition measure acceleration (change of vector).

Gyros by definintion measure change of rotation around an axis and this is the crux of the difference 

 

[meepmeepmayer]

1 hour ago, mike_bike_kite said:

This is probably a stupid question but aren't hall effect sensors used to detect magnetic change? What do they do in an EUC? I thought EUCs used accelerometers to detect how the wheel was orientated. I'm a bit confused (most of the time actually).

The hall sensors count the number of magnets going by, and thus establish the speed of rotation (at least at low speed).

You're right that this has nothing to do with balancing, an accelerometer is the only input for that.

The only connection seems to be that the speed of rotation must be known for the firmware to figure out whether to speed up or slow down to reduce the tilt as measured by the accelerometer. But I would guess that in theory you could live without hall sensors and just go by "more power" or "less power" compared to what happened a fraction of a second before, with only the tilt (accelerometer) as input.

[Tawpie]

2 minutes ago, Planemo said:

For the accelerometer/gyro argument, I would say euc's use gyros. Only because, in my view, accelerometers by definition measure acceleration (change of vector).

Gyros by definintion measure change of rotation around an axis and this is the crux of the difference 

Agreed... it's semantic. A "gyro" can be implemented with a spinning flywheel or a ring laser or a set of force vector sensors like accelerometers. Functionally, it's about rotation about the axis.

[RagingGrandpa]

EUC's use a 6DOF MEMS IMU, which measures accelerations in 3 directions and angular rates in 3 directions.
These are now high-volume and inexpensive, and are present in nearly every smartphone today.
(MEMS gyros use electrical feedback from a vibrating ring of silicon to measure rate-of-rotation. The ring moves back and forth less than 5 degrees.)

Gotway's IMU is MPU-6050, read more about it here.

p.s.: the IMU is also used as the EUC's board temperature sensor