Assistance Device for Braking

Other Hardware Motors, Mechanics, Power and CNC
1

The Opportunity
I have a son with Down Syndrome, he is 14. He owns an adult tricycle, we live in a culdesac. There isn't a lot of traffic and the entire neighborhood knows him, so it's a safe environment. He currently plays in the neighborhood and knows his boundaries, but the bike is a new level of freedom. He's able to ride the bike, but occasionally gets excited and takes off, heading down the road. I am working on a way to guide him home and prevent him from going to far.

The Solution/Idea
The idea is to program an arduino with a GPS board to limit the area the bike will operate. The device would give him color coded feedback (green/yellow/red) to let him know he's done too far, as well as apply the brakes to the bike as he gets out of he designated area. I have the ability to program an arduino with a GPS board so that it "knows" the area the bike will be allowed, as well as the feedback for the LEDs.

The Issue
Where I need assistance... I have researched to find a way to apply the brakes and been unsuccessful. I've considered something that would just pull the cable (haven't found anything that would do that and still let him pull it) to something like a robotic arm clamp that would apply to the back axle and act as a separate breaking system. I'm at a loss to find something that could apply that level of pressure (how to calculate that), something that could work in this manner. It would need to be strong enough to stop a tricycle and handle some wear and tear over time, work with an arduino... etc.

Any thoughts on how I can accomplish this would be greatly appreciated.

2

Lots of information, but no info on how brakes operate or even if the tricycle is battery operated.

Paul

3

Paul_KD7HB:
Lots of information, but no info on how brakes operate or even if the tricycle is battery operated.

Paul

Good points. The bike isn't battery operated, just a regular adult tricycle bike. It has one standard manual hand-brake you'd see on a regular bike. I'm looking for anyway to either operate the handbrake while allowing him to use it manually, or to add an additional type of braking system to the bike triggered by the arduino.

Douglas

4

vogtd:
Good points. The bike isn't battery operated, just a regular adult tricycle bike. It has one standard manual hand-brake you'd see on a regular bike. I'm looking for anyway to either operate the handbrake while allowing him to use it manually, or to add an additional type of braking system to the bike triggered by the arduino.

Douglas

The bicycle brakes I am familiar with have a rubber gripper that clamps both sides of the steel wheel. Cable sheath fastened to one piece of the caliper and the inner cable to the other.

Unfortunately, any reasonable, non-manually operated brake will not be proportional. I am thinking a solenoid to pull the calipers. All or nothing.

If you are mechanically inclined, you may be able to mount a second brake caliper to the front wheel and leave the current manual brake as it is. the new one could be solenoid operated, if you can add a 12 volt battery somewhere.

Paul

5

Paul_KD7HB:
The bicycle brakes I am familiar with have a rubber gripper that clamps both sides of the steel wheel. Cable sheath fastened to one piece of the caliper and the inner cable to the other.

Unfortunately, any reasonable, non-manually operated brake will not be proportional. I am thinking a solenoid to pull the calipers. All or nothing.

If you are mechanically inclined, you may be able to mount a second brake caliper to the front wheel and leave the current manual brake as it is. the new one could be solenoid operated, if you can add a 12 volt battery somewhere.

Paul

I hadn't considered a solenoid to pull the calipers because I wasn't sure if they'd have enough force, but love the idea. In my research I have found that it takes approximately 50-70 Newton Pounds of force to pull the calipers on a hand brake, which is between 12 and 15 pounds of pressure. The strongest one I've been able to find is by Adafruit and it'll do about 4lbs of pressure with 24vdc. Thoughts on a strong option?

Douglas

6

I may be talking out of my hat but, could a strong (not the dinky hobby type) servo with a proper horn, perhaps a capstan/winch sort of thing, be put into service here? It's analog nature would allow proportional operation. I'd think the braking force could be finely calibrated in software.

Or, not.

7

I think you may be onto something there. This wench would definitely have the pulling capacity: WARN 12 Volt DC Powered Electric Utility Winch

So tell me if I'm off my rocker here. I'm thinking an Uno, connected to an Adafruit Ultimate GPS Breakout, along with some type of Adafruit power Relay Featherwing which would then be tied to the wench.

Questions:

  • I've never used Adafruit products before, would these be acceptable?
  • Is the design above viable? (or would a better one work?)
  • would a shield GPS give me more capability?

Very much appreciate all the advice.

Douglas

8

Paul_KD7HB:
Unfortunately, any reasonable, non-manually operated brake will not be proportional. I am thinking a solenoid to pull the calipers. All or nothing.

The forces involved are large, mechanical advantage is essential, solenoids are not going to do this.
A small linear actuator with several 100N force rating should be able to apply the brakes slowly but
solidly. Something like these might be roughly right:

[ The 2000lb electric wrench will just destroy the trikes brakes, a 1.6hp motor is HEAVY too.. ]

9

MarkT:
[ The 2000lb electric wrench will just destroy the trikes brakes, a 1.6hp motor is HEAVY too.. ]

Not to mention the automotive battery to power it.

10

MarkT:
The forces involved are large, mechanical advantage is essential, solenoids are not going to do this.
A small linear actuator with several 100N force rating should be able to apply the brakes slowly but
solidly. Something like these might be roughly right:
http://studiodimeo.com/Images/photos/index.php?p=186

[ The 2000lb electric wrench will just destroy the trikes brakes, a 1.6hp motor is HEAVY too.. ]

I figured the actual device itself would need to be modified to insure it didn't apply more than a fraction of the pressure on the breaks, basically apply voltage for a half second or something. Looking through the linear actuators I found this Mini Linear Actuator that might do the trick. Apparently the company makes custom actuators and I've called them (they'll call back) to walk them through the idea I have an how it'd work. My only concern is it appears the low end pressure is 35lbs, albeit if they have the ability to make custom ones perhaps this can be adjusted. A small one with 1-2" of movement would be enough. (as you can tell, i'm not mechanically inclined)

Douglas

11

Mark, just spoke to some engineers at Progressive Automatons and they were extremely helpful in showing how arduino's can connect to their devices, how I can get feedback, and how it would work with the braking system. Thank you very much, and to everyone else. Will let you all know how this turns out. :slight_smile:

Douglas

12

vogtd:
Mark, just spoke to some engineers at Progressive Automatons and they were extremely helpful in showing how arduino's can connect to their devices, how I can get feedback, and how it would work with the braking system. Thank you very much, and to everyone else. Will let you all know how this turns out. :slight_smile:

Douglas

Good! Be sure whatever you develop is water proof and can't be tampered with.

Paul

13

14 year olds are pretty good at tampering with things. But they haven't yet learned to hide their tracks. If the bike comes home with the brake missing then he doesn't get to ride it for a week while you build a new one. It's a simple punishment that is directly relevant to the crime.

14

MorganS:
14 year olds are pretty good at tampering with things. But they haven't yet learned to hide their tracks. If the bike comes home with the brake missing then he doesn't get to ride it for a week while you build a new one. It's a simple punishment that is directly relevant to the crime.

When our boys were that age and younger, we had neighbor boys around all the time. One was Jimmy. He could not resist turning every knob and control, every switch, and anything else that might move. From then on we identified anyone with that tendency as a "Jimmy".

Paul

15

Yes, I forgot that he will be led astray by the neighborhood kids. They may think it's funny and he ends up getting punished for something he didn't do.

16

I think I'd have a look at a geared motor , so you have a "winch" type setup which could pull on a brake cable and apply the brakes - you might have to add a further brake calliper for it . BTW :What happens after you've stopped the bike ? Is he then stranded at the GPS fence ? Also it may stop him at a dangerous place ?

There is also a danger of a failure applying the brakes when not wanted ?

You can buy GPS trackers for cars that could say sound a buzzer or give you the ability to listen/speak

17

MorganS:
Yes, I forgot that he will be led astray by the neighborhood kids. They may think it's funny and he ends up getting punished for something he didn't do.

I don't see that happening here, and to Paul's comment it'll definitely be waterproof. :slight_smile:

MorganS:
14 year olds are pretty good at tampering with things. But they haven't yet learned to hide their tracks. If the bike comes home with the brake missing then he doesn't get to ride it for a week while you build a new one. It's a simple punishment that is directly relevant to the crime.

My son's 14 physically, but not mentally. The way I intend to build this it won't be possible for him to tamper with it away from the house, and the bike will be locked up when we aren't outside. Good points though.

hammy:
I think I'd have a look at a geared motor , so you have a "winch" type setup which could pull on a brake cable and apply the brakes - you might have to add a further brake calliper for it . BTW :What happens after you've stopped the bike ? Is he then stranded at the GPS fence ? Also it may stop him at a dangerous place ?

So, good thoughts, ones we've considered. We live in a culdesac at the end of another culdesac, which is a private driveway. There's no way through and very little traffic. The traffic that is here is limited to 10 miles per hour, his large red bike with lights would be very hard to miss. He knows what traffic is and has an understanding that it's to be avoided. His range from the house isn't going to be more than a few hundred feet and never when we aren't present.

hammy:
There is also a danger of a failure applying the brakes when not wanted ?

Have considered that, but he's been on scooters, green machines, and smaller tricycles and "stopped" them at inopportune times. I know it's hard to explain, but considering the environmental conditions, his mental age, and our proximity the brake apply is more of an emergency catch and training device for distance than something we'll depend on in complex situations (like higher independence, crossing streets, going farther away from home, etc)

hammy:
You can buy GPS trackers for cars that could say sound a buzzer or give you the ability to listen/speak

He's deaf and non-verbal, which you didn't know and I didn't include in the original message, but for other's who may want a device of this nature that'd be a great idea. Although I didn't mention it early I've been researching adding an 18-bit color TFT LCD display with the sign language "go home" or use symbols from his Proloquo2go device.