DIY Anti-lock Braking System 

My ABS is called "the brakes aren't strong enough to lock up" and it's never given me a problem

"DIY" and "braking" are a precarious combination

Imagine the neighbours watching him through the window, "yeah Bob hes doing it again, riding up and down his garden skidding on his bike"

Physics is the greatest teacher of brake control on a mountain bike. Crash enough times and you'll figure out what you're doing wrong to fix it. Ideally, you'll be a one trial learner.

My abs is called "dont pull the lever all the way" and it works perfectly fine

16:03 nice demonstration of abs giving you back control over the bike, balance and steering wise!

Why even in commercial devices the brake is released so significantly? The best choice would be a PID control to release slightly the brake to get the best possible deceleration according to tire friction, the deceleration would appear as constant (the PID loopback can be done thousand times a second).

This was fascinating to watch. The biggest improvement to motorbikes over the last 20 years has been in brakes, and I've often wondered how difficult it would be to create a retrofit kit to fit to older bikes that are still more than fast enough, but stop like a grayhound on a polished floor. One of those things that seems conceptually simple, but evidently complex in practice.

Well done mate! It really shows how hard is to replicate such easy to understand mechanisms. The first brake release mechanisms looked way cooler though ;-)

Wet grass? In England? Where did you find it? 😂😂

Your data should also allow you to calculate the friction of the surface from the first lock. You can then use this to predict the maximum safe breaking force and release the break to the ideal position. You'd just need to adjust the break pressure curve to allow the wheel to speed up again before clamping to the ideal pressure.

I thought this was going to be a video of you 3D printing your own bike out of ABS

This was far more interesting and technical than I first expected. Loved it! From a control systems engineer.

This is just fantastic. This video had me thinking about all sorts of things including why the ABS judders your wheels in an emergency braking situation.

"Maybe third time's the charm?" - unnamed ABS manufacturer

Very cool work! Perhaps a solenoid or other linear actuator would have better mechanical response time than the motor. Very good points about real-world applications too

16:51 i think he broke his leg

Rather than having an ABS system that releases when it senses a locked wheel, would it work to make them completely fly-by-wire where the brake lever is just an input to the computer to indicate percentage of braking force? At 100%, the computer would only apply the maximum force that would still keep the braking of the wheel within the ideal slip ratio portion of the graph. So, instead of trying to modulate the pressure after it's locked, only enough braking force would be applied to maximize deceleration without the lock up.

The motor response is too slow, i have a motorcycle with abs and its abs is phenomenon save me couple of times in emergency braking

Tom your topics for videos are extraordinarily excellent. I am studying automotive engineering and the actual ABS works in a manner very close to what you were trying to achieve. Of course the hardware response time there is ridiculously high. But the theory remains the same. Enjoyed the video. I might just try to make my own abs bike someday. Preferably hydraulic. Also difficult to achieve higher response in cable operated brakes as they have longer travels. Hydraulics on the other hand have negligible travel.

This reminds me of a problem I faced trying to tune my brother's turbo Miata. We were trying to get the boost to hold a steady 10psi, but the controller was extremely finnicky, sometimes it'd overshoot to 14psi (hitting 'boost cut' where the ECU cuts fuel to save the engine from damage) or it would wander around 7psi. It was using a PID loop with a few tables and miscellaneous values to help prevent excessive lag or overshoot. The output from the controller was a PWM signal, 0-100%. After many frustrated tuning sessions, we finally found the problem. The controller was using the entire 0-100% output range, but the valve was fully closed below 70%, and fully open above 80%. All we had to do was "clamp" the output between 70 and 80, and it immediately started behaving normally. I feel like this clamping could have been used on your setup so it doesn't have to spend any time with the rope slack or so taught that it takes a moment to get the wheel unlocked again, if that makes any sense. I know these projects are usually one-off, but I think the response time of the system could be improved massively with a bit of tweaking to the software ;)

Love this kind of experiments, it takes a lot of time though, but research is worth it.

That's one of the videos that made me retrofit an ABS on my bike (which never had it as an option from factory). Oh and later upgraded it into a traction control system with 4 different modes. And it works like charm - saved my ass a couple of times. Thanks for an inspiration!

Wow. Very cool. Loved the multivariate sets and data analysis, knowledge as regards appearing as intuition, and the comprehensive narrative. Cheers!

Superb job man, I'm greatly impressed with the amount of work that went into this one! Looking forward to the next project. :)

Dude, you have one of the best hobbies ever! I wish I could come up with stuff like that by just tinkering around.

This has been on my mind for awhile, I am subscribing to watch your journey!

I really appreciate your analysis of *whether* and *for whom* ABS might actually make sense on bicycles. Requirements engineering is a key part of engineering!

Glad you ditched the first prototype, as you were running into the prpblem with this being a cable based abs braking system. When you look at a cars abs system, it uses hydraulic brakes and a very expensive abs pump to quickly and precisely pump individual brake circuits. You want the fastest possible mechanism controlling the pulse and release part, like a solenoid or high end RC servo. These slow stepper motors arent cutting

Tom, how about using a solenoid for the actuation? The response times would be very quick

You're actually designing a PID controller. Very educative. Thumbs up!

I love your videos Tom. I have learned quite a lot on through watching your videos. Keep it up bro!

Are you sure the motorbike uses an optical sensor for the wheel speed? I've only ever seen vehicles using hall effect sensors, since the optical sensors would be subject to dirt and grime blocking the light emitter or detector. I've been looking forward to the next video, so glad it came out! Another fine video presentation. Nicely done!

Spray some wd40 on the brakes then they wont lock 🤣🤣

Great job man, a super interesting video actually, congrats!

1:08 "Why does it keep floating out of focu... ooooh there we go, that's why!!!!" 🤣 First video I've seen, and I'm already a big fan haha.. Hooray RU-vid/Google hoarding my data, now knowing I recently got a bike 😁🤗

bro this guy got so much in his head

You could use a servo controlled pressure unloading cylinder ,just put it in line with the caliper and move it in and out with a servo....

this is briliant. Amazing work. I think, like abs on a car, the best way would be to use hydraulics for a quicker response time. However the budget would be immense to develop that

As an auto mechanic, I finally felt fairly intelligent watching one of your videoes.

Hi Tom. I see that the motor turns around 180° or so, in and out to allow or disallow you to pull back on the brake lever. It looks binary, either it's on or off.. My question is.. Why don't you program the motor to turn slower on the way back and also not turn all the way back. It would reduce your delay. Thanks for your great video. Very inspiring.

You could add a value for brake force and combine it with wheel speed to sample the break force right before the wheel skids, so the abs tries its best to avoid locking

Good job. I would have like to see a side by side comparison of the abs vs without abs to see which stopped quicker. And maybe a little about friction coefficients dynamic vs static on different surfaces.

When you mentioned accelerometer, you reminded me of inertial reference units used in aircrafts to measure position of the aircraft. Maybe something similar can be used for predicting speed even if both wheels lock up

I was getting concerned when half way through the video you hadn't mentioned accelerometers yet.... You were just trolling us though!

While mounting the stepper motor like you did is probably the easiest way to do it, I sort of wish that you had mounted it closer to the actual break instead. Also, perhaps it would be possible to attach something onto to the breaking wire. I'm thinking a small clamp that you could attach the stepper motor lever to. Your code is doing its job, but there's a lot of mechanical delays in your design. Since you're using a rope, applying tension to it requires a lot of time, and the stepper motor has to rotate a lot to apply that tension. I know that you're on a budget, but a high torque servo might serve this purpose better than a stepper motor. The horn of the servo would then be attached to the clamp. I think that you'd drastically reduce the mechanical delay this way, and you'd see a breaking action closer resembling that of a car. Apart from that, this concept and execution is probably your most interesting project yet, and that's saying something! Cheers mate.

Hi Tom, great work !! I think everything you do up to the point of operating the brake lever is fenomenal. To make a more effektive, cheaper and simpler way to pull and release the brake lever I would swap the stepper motor for a cheaper regular DC brushed 540 motor and tilt it slightly forwards so the string can pass on the outside of the lever on the motor axel. (Swap to a more reinforced string as well) Then it could just be left spinning in the same direction pulling and releasing the brake lever much faster. Simple engineering without any motor control electronics just a relay to kick it in when all criteria's are met :) The sound would probably also be more similar to a true ABS system as well.

Fantastic video! Love the testing and explanations.

I did use a bicycle to go to work after 10 years of driving abs-enabled motorbikes. I did end up doing 2 stoppies during emergency breaking, one of which did send my flying over the bars. that's the price for getting used to ABS.

1:17 I cracked up when I saw that

After watching this again, I think the system could benefit greatly by having a force sensor mounted to log tension along the brake cable or hydraulic pressure in the brakes. I'm thinking that a logged force could be used to find a target for the stepper motor during slip events. My thinking is that once the abs activates, the swinging between stopped and rolling can be reduced. Might not be able to prevent the wheel locking the first time, but maybe could prevent the wheel from locking a second time.

Excellent video as always! Thank you Tom. My like.

1:18 "That autofocus THO"

Antilock brakes on a mountainbike are pretty pointless but on a motorbike the new 'cornering abs' systems are brilliant. Still very clever stuff though and great video :)

My ABS is "stop pressing the brakes when it locks and press the brakes again, repeat that until the bike stops" It works fine, faster than your mecanism in the video, and it saved me from many crashes. Pd: Sorry if i wrote something bad, I'm still practicing my english.

Dude ! Hats off to your efforts just amazing

I was waiting for a proper comparison of break time/distance with and without the "ABS" !

i've had to emergency break a few times on my bike and i've skidded on ice a few times too but i've been biking daily for 4 years

Great job!! Thanks you for doing the work most of us just dream about doing!!

I like your videos, the thought process, and simplicity of implementation. I think that with a (much) faster actuator ABS might actually be useful on a bike, at least for the less experienced riders. Thanks

try using a gearbox and a brushless or brushed motor, with some math you'll find that you don't need a very powerful motor so you won't need to spend too much if you calculate right the gear reductions. you can cut the cogs with the cnc cheers!

So using the same knowledge you could create a traction control system for an electric bike like mine. I have a hub motor in my front wheel. If I'm going up a slippery hill and the front wheel loses traction while under power I may go down. If you could sample the speed of both wheels and cut power to the motor when the front wheel is going faster than the back wheel it would prevent some crashes and only require some code and the speed sensors.

Great item to have in our weekender horse trailer!

the image at 3:46 with the entirely destroyed high current device is hilarious!

me: *hehehe bike go skrttt skrrrt* Tom: *skkkrtttt OOWWWW*

I wish you'd show controls without abs so we can see how much the abs improved braking distance

really enjoyed this video man keep it up

I ride a lot in places were you would be prone to brake locking but the more experienced you are the better and the good thing about bikes is you feel what the bike is doing knowing how much brake to apply your fingers will do a much better job at it really, it comes natural to me you can hear it and feel it starting to lock up in a car or motorbike yeah its needed you don't feel the things as good in them since there heavier and more sturdy

15:00 How about using an arm from the actuator to brake handle? It seems that the rope hack added so much stretching that it causes extra lag to the system. Another way would be to use actuator to move *pivot point* of the brake handle instead of moving the handle itself. With adequate movement of the pivot point, the same handle pressure can result in different hydraulic pressure. For example replacing the brake handle pivot bolt with a part that has off-center middle section it could move the handle pivot point a lot with only 180 degree rotation from the actuator (you obviously cannot ever get more than 180 degree range from actuator with this setup, note that you could also get faster on/off cycle with running actuator full speed in one direction).

16:08 actually pretty impressive if you realize how fast the human brain is responding to skidding with a steering input to hold the balance 😮

Great vid, I learned a lot! Thanks!

Full of informative content....big thumbs up for your analysis......and for final success.

Why not use a modified slip ratio equation? SR= (av-aw)/av, using acceleration instead of velocity. That way you don't have to work with a estimated speed but instead values that you know exactly.

The solution to the problem of slow response is to use pressure rather than position actuation, fast PWM on that pressure and a duty cycle proportional rather than bang-bang control. To not lock the brakes, don't ever fully brake for a visible length of time. If your response time is not fast enough due to a slew rate problem, don't respond the whole way. Let the braking force back some percent upon slip and then reapply by that percentage the moment you see the next nth optical encoder count. ~One electrical engineer with a control systems background

You hit the nail on the head perfectly when you said who would require an anti lock brake system on a push bike but nevertheless the walk was impressive but if you integrated the system stopping you going over the handlebars that would be very useful good pal.

No idea if you'd ever revisit this project but for hydraulic disc brakes you could possibly plumb in a second lever/cylinder to act as a regulator for the system. This could possibly be servo controlled as the torque required to operate would probably be significantly lower as it doesn't have to operate against your hand. I really love all your projects :)

Long before ABS, as a professional emergency services driver (fire) we were taught cadence braking; essentially manually operated ABS. I used that when driving my own car pre-abs and do the same with the front brake on both motorcycle and bicycle. It is an acquired skill but still very effective. It works best on hydraulic cycle brakes but I have also found that the front disc is so easily contaminated with road muck that it effectively turns itself into ABS by alternately slipping and locking but it is very noisy! I used to clean my front disc and pads very regularly but found it locked up on gravel far too easily so I left it alone. It works!!!! It's noisy but very effective (self) cadence braking. No need for expensive ABS as long as you can stand the noise plus the noise itself turns you into a very careful breaker; effectively a verbal cadence braking warning. It works for me and has done for many years. I'm 71 years of age and still riding 100+ miles per week safely. 😀

Why not release the brake only partially/ using PID to match the wheel speed to little below the speed calculated by the accelerometer?

Top stuff! Really interesting videos! Curious as to what bike is that?

For the ABS triggering, you could try combining all of the different triggering mechanisms into one: 1. Zero Wheel Speed 2. Peak Deceleration 3. Accelerometer-estimated Slip Angle. Additionally, you could add a GPS speedometer, which could act as a backup for measuring the bike's speed. You could also add a pair of compasses and 6-axis IMUs (one compass and IMU for each wheel, mounted on the frame and fork respectively), these would be a good future proofing mechanism.

Hey Tom, it's quite impossible for a commercial motorbike to use an optical sensor for wheel speed, that must be an inductive sensor. Keep it up!

does this bosch bicycle abs reduce the braking distance at all?

This guy just ruined his backyard to teach us stuff. Respect.

Impressive that you were able to make something so simple and useful so complex and dangerous

Next time would be good if you walked through the code on the next one of your videos like this. Can you do traction/ ESP on a remote control car??

I have a manual ABS installed... in my brain

I just had an idea for solving the mechanical issue: Compressed air. It would probably only work with rim brakes, but basically, you shoot a little jet of compressed air through a hole in the brake shoe, temporarily lifting the shoe off the rim on a cushion of air. You could modulated the braking much more quickly just using an electronically controlled valve. Of course you'd have to have a small tank on board, but it would probably weigh less than that servo and its battery.

Great project great job! Keep working

Why not go hydraulically actuated powered by an accumulator and pump assembly? Then all you need to do is modulated the pressure output, not wait for the motor to move.

You can also put a speed indicator on the back tire and when the front tire is going slower then the back it would disengaged the front brake enough to get is closer to the back tires speed

Someday you should also go through the programming aspect of these projects. Would be really interesting.

Very Cool. Big up man. First improuvement : change the rope for a metal cable, tune the distance of reaction on the cable. Pproposal : it is all about tension of the brake cable, a S shape for lengthen the cable run, with some spring for reduce the engine load. (sorry for my english, i'm a french :c ) :p

It probably need a PID controller to prevent oscillations of breaking force.

Do you think it would be possible to make a totally mechanical abs system by using a slotted rotor parallel to the brake rotor (eg where you have the black 3D printed rotor on the front now) that intermittently disengages the brake based on the slot spacing in the rotor? It would always be engaged when the brake is engaged but way less money to make and doesn’t require any electronics. For reference, something like the old bi-plane guns that would shoot through the propeller without hitting the propeller due to a mechanical timing mechanism that disengaged the trigger when the propeller was in front of the barrel

Great work. ✔️💯🏆 Thanks so much for sharing. 😉👌🏼

I love science. Thank you!

What made you go for a stepper motor? A geared DC motor (such as a windshield wiper motor) would have plenty of oomph as well as speed at a very low price

My bike has rim brakes, and it stops instantly if I squeeze the brakes all the way, at any speed. So, in that case, this system would prevent unintentional front flips.

good effort, looks like it works like my motorbike

Thats was so cool to see!