How is purely torque-sensing PAS actually implemented?

[smorgasbord]

From the pages below they mention a 104 magnetic pole per revolution, which would suggest they can measure actual cadence with it.

Pedal Sensor / Torque + Cadence Sensor

Dual cadence + torque sensor hardware for Current-Series E-bikes. Frame-mounted rear dropout torque sensor. Made from a CNC milled block of 7000-Series Aluminum. Built-in high sensitivity digitally processed cadence sensor for near zero-lag startup and improved noise filtered torque-sensing over...

www.juicedbikes.com

That seems nonsense given idbike's own page on the TMM4 torque sensor:

Sensors

IDbike develops and produces components for electric bikes, such as torque sensors, controllers and displays.

www.idbike.com

The TMM4 sensor consists of a housing of engineering plastic, which holds a printed circuit board (pcb) , a magnet and a small set screw, which is used to calibrate the zero value

The sensor, mounted on the sensor plate, measures the deflection of the plate caused by the chain force. This, in turn calculates the pedal torque of the cyclist. The deflection is detected using Hall technology and is maximal 0.1 mm.

Unless there's some compute in there to look at chain tension changes and associate them with pedal cranks, which seems pretty advanced....

 

[scrambler]

The TMM4 sensor does not have a cadence sensor, it is only a torque sensor.
But IDbike licenses their sensor technology to a number of bike manufacturers, who then make their own version of it.

Juiced bike is using their own modified version that adds a cadence sensor (which appears to be capable of measuring the cadence) using a magnet positioned close to the sprocket.
What they actually do with it would have to be asked to them

IDbike TMM4 sensor does not have the added cadence sensor shown below on a juiced version.

 

[Jeremy McCreary]

Is your bike a juiced bike?

From the pages below they mention a 104 magnetic pole per revolution, which would suggest they can measure actual cadence with it.

Pedal Sensor / Torque + Cadence Sensor

Dual cadence + torque sensor hardware for Current-Series E-bikes. Frame-mounted rear dropout torque sensor. Made from a CNC milled block of 7000-Series Aluminum. Built-in high sensitivity digitally processed cadence sensor for near zero-lag startup and improved noise filtered torque-sensing over...

www.juicedbikes.com

Torque vs. Cadence Sensors | Pedal Assist Juiced Bikes

Pedal assist e-bikes often come in two different types: Cadence Sensor & Torque Sensor. Click here to learn about the differences & benefits of each!

www.juicedbikes.com

Surface 604, not Juiced, but my TMM4 looks exactly like the one shown at the 2nd Juiced link. The cadence-sensing part is positioned to watch the teeth on the nearest cassette cog and is marked specifically for 11 teeth on that cog.

Now that I think about it, the most such a sensor could learn from this arrangement is cassette speed. And since the sensor/contoller system has no way to know what gears I have, much less which one I'm in, no way to get crank speed from that except in one special case: Zero cassette speed means zero crank speed.

So ultimately, my TMM4's cadence sensor can't be anything more than a pedaling yes-or-no sensor — just like on a simple cadence-sensing bike. The 11-tooth and 104 figures presumably just go to resolution.

This answers the question at hand: My bike gets its natural power delivery from torque-sensing alone. For safety, the cadence sensor just disables the motor when the cassette and crank aren't turning. No knowledge of rider power input needed.

 

[scrambler]

You are right that at most it could capture wheel rotation speed but not crank. You could inquire with the company if they do any use other than pedaling y/n.
Which makes me wonder if it is just a replacement for the wheel magnet normally used to calculate bike speed...

 

[Stefan Mikes]

Surface 604, not Juiced, but my TMM4 looks exactly like the one shown at the 2nd Juiced link. The cadence-sensing part is positioned to watch the teeth on the nearest cassette cog and is marked specifically for 11 teeth on that cog.

Now that I think about it, the most such a sensor could learn from this arrangement is cassette speed. And since the sensor/contoller system has no way to know what gears I have, much less which one I'm in, no way to get crank speed from that except in one special case: Zero cassette speed means zero crank speed.

So ultimately, my TMM4's cadence sensor can't be anything more than a pedaling yes-or-no sensor — just like on a simple cadence-sensing bike. The 11-tooth and 104 figures presumably just go to resolution.

This answers the question at hand: My bike gets its natural power delivery from torque-sensing alone. For safety, the cadence sensor just disables the motor when the cassette and crank aren't turning. No knowledge of rider power input needed.

Your observations are correct regarding hub-drive motors.
Still, bear in mind a decent mid-drive motor applies from five to six sensors working together.

 

[mclewis1]

Your observations are correct regarding hub-drive motors.
Still, bear in mind a decent mid-drive motor applies from five to six sensors working together.

Stephan, I can't believe after all this time you still have these outdated and incorrect assumptions and make absolute statements that suggest one configuration is good and the other is bad. The comments above about cadence PAS and the TMM4 torque sensor apply only to the particular ebike setups mentioned, not to all configurations.

Once again (after many discussions) ... It's not simply about hub motor bad, mid motor good. It's more about HOW the motor is incorporated into the ebike and what control systems are used that determines feel and effectiveness of the power assist. Plus the total number of sensors has NOTHING to do with it either - again it's not more good, less bad. A hub drive configuration can have a few or just as many well integrated sensors as a mid drive.

I ride a very solid reliable commuter/city/road bike that has a very bicycle like feel - particularly at lower power levels. It's uses a light weight geared hub motor with 6 (gasp) well integrated sensors that provide a safe and comfortable ride (pedal cadence, motor speed, motor temp, throttle position, and brake lever position). My PAS knows the difference between the crank being slowly turned at a stop or pedaled backwards to reposition the pedals (no power), pedaled at low rpms (wanting lower power) and higher rpms (wanting more power). With higher pedal rpms the power to my motor is also applied progressively (or ramped up) providing a very natural or bicycle like feel and certainly not anything like an on/off switch. The control system I use takes input from all the sensors and ensures that this simple but highly reliable setup provides this natural feel and operation.

From Grin's website "The V3 Cycle Analyst allows for basic PAS sensors to vary the power in response to the rider cadence, which effectively emulates a torque response as most people spin the cranks faster when pedaling at higher efforts."

If however I was building up an off road MTB style bike I'd probably incorporate a bottom bracket based torque sensor for even finer control over power delivery at lower rpms ... so that would be what now, 7 sensors?

 

[Stefan Mikes]

(pedal cadence, motor speed, motor temp, throttle position, and brake lever position)

What about:

• Torque sensor
• E-bike speed sensor
• Motor speed sensor
• Pedal cadence sensor
• Accelerometer
• Inclinometer
• Motor temperature sensor
• Battery temperature sensor
• Voltage sensor
• Amperage (current) sensor

Throttle sensor is useless with a mid-drive motor. Brake lever position is useless, too, although my Vado 6.0 has even that for the STOP lights...

 

[Jeremy McCreary]

What about:

• Torque sensor
• E-bike speed sensor
• Motor speed sensor
• Pedal cadence sensor
• Accelerometer
• Inclinometer
• Motor temperature sensor
• Battery temperature sensor
• Voltage sensor
• Amperage (current) sensor

Throttle sensor is useless with a mid-drive motor. Brake lever position is useless, too, although my Vado 6.0 has even that for the STOP lights...

Since my lowly display reports ground speed, instantaneous motor power, and remaining battery charge in percent, and the tail light flashes when the brakes are applied, the bike obviously has more than just the torque and cassette rotation sensor already discussed. Good for you that you have even more.

Could my power delivery system be more sophisticated? Of course. Would I like to see rider power on the display alongside motor power? You bet. Do I pine away for lack of these extra bells and whistles. Not in the least.

My one minor quibble WRT power delivery: A little surging when I find myself above PAS 5/9 in too low a gear. Upshifting to the gear I should've been in to begin with takes care of it, and I rarely ride with that much assist anyway. Zero urge to scrap the bike for one you'd approve of.

 

[mclewis1]

Throttle sensor is useless with a mid-drive motor. Brake lever position is useless, too, although my Vado 6.0 has even that for the STOP lights...

More uninformed drivel ... that would be news to the 10s of thousands (Bafang, Tongsheng, etc.) mid drive based bikes with a throttle.

 

[Stefan Mikes]

More uninformed drivel ... that would be news to the 10s of thousands (Bafang, Tongsheng, etc.) mid drive based bikes with a throttle.

Throttle is useless in a mid-drive motor e-bike. Bafang installs it to save the wannabe cyclists in some countries from unavoidable death when they try to move their 70 lb fat tire mopeds from the intersection

 

[Rexlion]

Don't some mfrs feel that a brake sensor was helpful for telling the motor to stop driving the bike when a person wants to stop?

Didn't know this could turn into a pissing contest: "My ebike has more sensors than yours!"

 

[Stefan Mikes]

Don't some mfrs feel that a brake sensor was helpful for telling the motor to stop driving the bike when a person wants to stop?

On a mid-drive motor e-bike, you just stop pedalling to stop the motor. Unless you are as stupid as to be pedalling while braking.

The OP question was torque sensing only. The technology can be far more refined than that.

 

[Kayakguy]

good one. I did way to many lego till I started riding more could not afford both. lego cost more then e bikes.

Grandkids have Lego, and after seeing how many unique individual bits there are (in the millions?), and how much they cost, I'm glad they didn't exist when I was a kid. All that was available were Erector set (too expensive), Lincoln Logs, and Tinker Toys. I did have a minimal Lincoln Logs set, and a Tinker Toy (note absence of plural). I got most of my fun disassembling clocks and riding my single speed coaster-brake Columbia (not as cool as Schwin) all over creation. My dad taught me how to make flour and water paste (mistake!!) which let me paste my Lincoln logs together for a "permanent" structure. We had heard of "3 speed English racers," but didn't know anybody who owned one.

 

[PedalUma]

Grandkids have Lego

@Jeremy McCreary lives in the Mecca of Lego. His town has Lego Land. When I was a kid I had Legos but they were still blocks and never had characters, or theme specific parts, or directions. It was free play and creative. Now they do with lots of licensing. Watch out walking in a kid's room barefoot.

 

[PCeBiker]

When I was a kid I had Legos but they were still blocks and never had characters, or theme specific parts, or directions. It was free play and creative.

Me too,..
I just had the basic blocks and "sheets"?
I had to make up everything I made.
I had just enough blocks to make a house for my hamster.
It was a hamster house for over 5 years.

All that was available were Erector set (too expensive), Lincoln Logs, and Tinker Toys. I did have a minimal Lincoln Logs set, and a Tinker Toy (note absence of plural).

My friend had a metal Mechano set.
He could make all kinds of machines.
It had wheels and wind up spring motors.

Tinker Toys rings a bell, but we had Tonka Toys.

Of course I had the dump truck. My friend had the front end loader. It was WAY more funner!!

I got most of my fun disassembling clocks

My mom used to put me in my room for a time out with the alarm clock set outside the door to let me know when I could come out.
I took the clock apart when I was 8.
It was the same as this clock but it was beige.

and riding my single speed coaster-brake Columbia (not as cool as Schwin) all over creation. We had heard of "3 speed English racers," but didn't know anybody who owned one.

I was lucky.
I had a 3 speed with a shifter on the "top tube" and a 2 speed.
The 2 speed would switch between 1st and 2nd gear when you pedaled backwards, so it had rim brakes.
I had many coaster brake bikes, which I of course had to take apart and investigate.


We also had clackers as kids,..

Those things were cool!!
You'd get the balls bouncing on the bottom, then wing it up and get it clacking top and bottom at 70,000 RPMS.

They were banned a few years later, because they were exploding and shooting shrapnel into people's eyes and blinding them.
I still had a pair up until about 10 years ago.
Mine were blue.

 

[KylerLaird]

I mentioned that I was reviving a bike project earlier in the thread. It's been up and running for awhile. Pure torque control. I love it.

I set up a 27" fat tire bike the same way and had a wonderful test ride before the torque sensor died.

I also bought a nifty looking trike with a torque sensor and I can't even tell if it works. It might be gated by cadence, which makes it a lot less useful. Need to rip out the controller on that one.

 

[fooferdoggie]

I mentioned that I was reviving a bike project earlier in the thread. It's been up and running for awhile. Pure torque control. I love it.
View attachment 165605
I set up a 27" fat tire bike the same way and had a wonderful test ride before the torque sensor died.

I also bought a nifty looking trike with a torque sensor and I can't even tell if it works. It might be gated by cadence, which makes it a lot less useful. Need to rip out the controller on that one.

looks like a real ball buster.

 

[Stefan Mikes]

looks like a real ball buster.

It looks like a ride for a dying former motorcyclist

 

[Jeremy McCreary]

@Jeremy McCreary lives in the Mecca of Lego. His town has Lego Land. When I was a kid I had Legos but they were still blocks and never had characters, or theme specific parts, or directions. It was free play and creative. Now they do with lots of licensing. Watch out walking in a kid's room barefoot.

The real Mecca of LEGO is Billund, Denmark, site of the original plastic LEGO factory (still their main plant) and later, the original LEGOLAND. The latter is a celebration of LEGO with many amazing displays aimed at all ages.

The LEGOLAND here in Carlsbad is little more than an amusement park aimed at small kids. No thanks.

Yes, recent sets put too much emphasis on franchised themes like Star Wars and too little on free imagination. But still a phenomenal building system with well over 10,000 different parts not counting color variations.

I build working mechanical things — mainly with loose parts from www.bricklink.com — and pay little attention to official LEGO sets.

 

[PedalUma]

It is amazing how gyros seem to defy gravity. The clackers are like an amazing mostly forgotten weapon, bolas. I would like to see it against a drone. They can take down a horse. Super simple and highly effective.