BSM compatible Road Armor bumpers on sale

As an engineer, I don't quite understand why Road Armor set the BSM unit so far back as they did. The only thing I can think of is that they wanted to multitask and create a step as well. Personally, I would have designed it to be as flush to the surface as possible.

Like others, I do not have the knowledge of the true functional aspects of the BSM system. I can also relate to both sides of the argument being presented, but in all honesty we just don't know. Yes, the BSM sites a little back in a tunnel like fashion, but this may not hinder due to signal reflection from each side equally distributing appropriate signals. As mentioned above, someone simply needs to test this out and document the results.

 

I should also clarify that @Saltyhero13 raises valid points and I am just playing devil's advocate because there are several unknown variables. I'm equally concerned about signal issues, but I'm open to the possibility that the sensors will still function as intended. We just don't know at this point.

 

What a soup sandwich this turned out to be! (I'll see if I can add pictures to help understand the text better, I don't have the time right now)

This is an approximation and not a substitute for real world testing. Its a best "guess" effort based on a few knowns.

Note that a visual inspection of the bumper will be a good approximation to where the cut offs zones are. Stand 11.5 feet next to the the Tundra's starting at the rear bumper and walk parallel to the truck moving forward. Note when you can no longer see the sensor but do not pass the mid point of the tire. Do the same standing at 6.5 feet and 1.5 feet. You can do the same walking backwards but do no go beyond 24 feet behind the vehicle.

The TLDR You might loose most BSM forward of the bumper and possibly half at rear.

Worst case scenario BSM is adversely impacted. I would expect the clipping issue will affect detection forward of the bumper. It is hard to say exactly how much since we don't know the shape of the sensor's lobes, angles or the system's screening logic. You could possibly loose anywhere from 1.73 to 2.8 ft using the closest detection point (1.9 at the 6.5 mid point); for reference 3.3 ft is close to the midpoint of the rear tire. In practical terms, vehicles passing may appear to leave the blind spot earlier than normal and vehicles you pass will trigger the sensor later; it would feel like a delay varying relative to your driving speed.

There is also an expectation clipping will occur rear of the bumper. What the impact is will be hard to judge. The BSM doesn't work for objects behind the vehicle, here the inside of the rear facing lobes will be clipped. It may make vehicles entering the rear beam look smaller (smaller cross section). This could possibly cause the system to alert you to vehicles passing from the rear later and and make vehicles appear to leave BSM later. If this is the case you may be loosing 4.3 feet of rear BSM zone. I'm less confident this is true or as bad.

The RCTA may be slightly degraded for the same reasons; in practical terms it doesn't matter as much. When backing up the rear facing lobe is sensing first, the inside areas (closer to the vehicle center line) that could be clipped will be closer to the back of the vehicle. The lateral lobes will be clipped but this doesn't matter either, the forward portion of the lobes that are clipped are the last to be exposed to the street when reversing.

Key #s and facts:

BSM sensor angle based on calibration video 79.1 facing rear. (Right triangle with 28 and 146): https://youtu.be/_RPCYwpN6YE?t=270 90 would be perpendicular to the Tundra
Yes its a Sienna. I looked at the Tacoma OP Check guide but the angle looked too steep when I ran the numbers (RT with 2192 distance form bumper and 1783.7 from reflector to bumper corner): http://www.ttguide.net/operation_check-392.html

I looked at the #s in four scenarios; all the combinations for center beam vs whole pad and 2inch vs 3 inch. I used and ideal 180 as a baseline for full unobstructed sensing and worked out how much would be lost as a shadow. The issue is the sensor emits two nodes. One perpendicular to the sensor face and one at 45 degrees. I am assuming the signal at the 45 degree angle is facing laterally. This is bad news for any hopes that the channel reflection would cover the shadow areas. The lobes emitting at 45 will cast into the shadow but most of it will be in the opposite direction.

Scenario 1:
Recess = 3 inches
TX from whole Pad with 3 inches
Blindspot/Shadow = 45 degrees on both sides
OEM-ShadowX2 = 90 Degrees Remaining
Critical angles 1/2, Front, Rear: (45/35/55)

Scenario 2:
Recess = 3 inches
TX from pad center = 1.5 inches
Blindspot/Shadow = 63.435 degrees on both sides
OEM-ShadowX2 = 53.13 Degrees Remaining
Critical angles 1/2, Front, Rear: (26.565/16.565/36.565)

Scenario 3:
Recess = 2 inches
TX from whole pad center = 3 inches
Blindspot/Shadow = 33.69 degrees on both sides
OEM-ShadowX2 = 112.62 Degrees Remaining
Critical angles 1/2, Front, Rear: (56.31/46.31/66.31)

Scenario 4:
Recess = 2inches
TX from pad center = 1.5 inches
Blindspot/Shadow = 53.13 degrees on both sides
OEM-ShadowX2 = 73.74 Degrees Remaining
Critical angles 1/2, Front, Rear: (36.87/26.87/46.87)

3 inch aperture ranges from 53.13 to 90
2 inch aperture ranges from 73.74 to 112.62

Best case is #3
Worst case is #2

Ideal but not realistic for the sensor is 180 degrees. Based on the BSM and RCTA below I suspect it isn't more than 140 to 150 Degrees and could possibly be narrower.

Angle of sensor is 79.1 +/- 3.6 . I'm using 80 for simplicity; I will need to pay attention for issues falling +/- a degree

BSM
For the 3.3 ft x 11.5 ft area forward of the bumper the angle of detection is ~26 Degrees at 11.5 ft, ~37 Degrees at the midpoint and ~75.5 Degrees at 1.5 ft (the closest distance the sensor will respond)
For the 9.8 ft x 11.5 ft area rear of the bumper the angle of detection is ~ 30.4 Degrees at 11.5 ft, ~56.5 Degrees at the midpoint and ~71.3 Degrees at 1.5 ft

RCTA
65 x 24 10 Degrees at furthest point, 27.1 Degrees, ~32 Degrees midpoint, 76.4 Degrees at closest point.
18 x 24 43.1 Degrees at furthest point, 61 Degrees at the ~8 foot midpoint, 76.4 Degrees at closest point.

With these angles I assumed the nodes would reach all the areas in the coverage area. In reality its not so. The nodes are usually tear drop shaped so there are areas with in the zone that are not covered.

**Editing for clarity

 

An additional critique of this design and a note about aftermarket bumpers supporting BSM and BSM calibration. After watching a few cal vids this bumper looks like it will make it very difficult to calibrate BSM/RCTA. To calibrate these sensors you need to access the sensor mounting points in order to make orientation adjustments. Usually this is done from the front of the sensor with no obstruction in front. Not sure how it would work with this set up considering you would need to access this from the rear. Curiously enough only one of the sensor lobes is used to calibrate BSM

I'm not sure what impact moving the sensors inline with the bumper's surface will have but I would expect some untended consequences while fixing the clipping issues. It will push your zone out by 2 to 3 inches (makes your dead zone slightly larger) and it could complicate calibration as well. Judging by the pictures the BSM sensors look like they are actually in the original OEM position but the bumper sticks out 3 inches more. I don't have any indication they signal to each other via RF but they are linked via a Master/Slave. I would guess it has no impact but its unknown at this time.

Looking at the OEM design the sensor looks well protected. It is encased in a shroud. I would be curious to see what protection this design offers from wheel debris.

I'm done derailing the thread any further, I'll be throbbing along now.

 

Bumper is up and running, everything seems to be functioning so far...

 

Looks like you got it adjusted pretty good. I still haven't ordered my flush mounts.

 

Yea, didn't seem like it needed much adjustment, I just threw it on and bolted it, had to center it but that's about it.

 

Looks good. Have you done much testing with the BSM?

 

Not really, just a 10 min. ride.

 

Way too technical for my simpleton brain to follow. Thank you for putting in all this time and effort! I don't think anyone here would consider honest research and voicing of concerns a derailment. I certainly don't.

 

Looks like you couldn't relocate the sensors if you wanted to:
https://youtu.be/C7eQU3pWRrE

 

It would be easier to follow with pictures. I'm putting something together, its just tedious.

@Motor71 real world experience is going to trump anything I guestimated. Honestly I hope I'm wrong.

 

Thank You for all the hard work I am hoping in the next few days we can get some real world feedback so I know whether to cancel my order. For me they dont have to be perfect I just need them to work accurately enough to detect my blind spots.

 

I Would take that with a grain of salt . They just did not want to put the effort into supporting BSM

 

Or preserving airbags....

 

@Motor71


Hello Sir,

‘A couple of quick questions on the infamous rear Road Armor bumper.
* How would you rate its ability to maintain factory Blind Spot Monitoring, I am in my 60s and rely on that feature everytime I drive. That being said does the BSMs capability to monitor cars in your blind spots work well enough to alert you if someone is “in your blind spot”?

* The cutout where they are located looks like a perfect spot for a step, are they big enough to get a foot in and if so could you accidentally damage them if you kicked the sensors with the toe of your shoe/boot?

* Lastly how well are they built, are they stout compared to say a DeMello, C4, Fab Fours etc...

 

Im

I'm in my 40s, so I like the bsm feature very much. Since the bumper was installed I couldn't really tell if the bsm was affected since it functioned the same as the stock bumper imo.

The cut out is about 3 inches in and about 5 inches wide so I do use it as a step, but I can see how you can accidentally kick the sensor if you stick your foot in too far.

Lastly, I don't know about the other bumpers, but this bumper is solid and it does stick out a little more than stock. Let's say I wouldn't mind hitting an elephant with this bumper.

 

Are able to notice if the area of detection shrunk? It extends about 10 beyond the the rear bumper and forward to the mid line of your rear tire.

 

Does it also pick up cross traffic while in reverse?

 

I couldn't tell.

 

All of our wallets are dependent on you @Motor71. No pressure Devil.

1. Pictures
2. Driving tests/field notes
3. Cross traffic while in reverse
4. Pictures
5. Knife hand

 

I could have modeled the second node incorrectly in which case it would mean RCTA would be disrupted. I still expect the sides to be mostly impacted.

Keep us posted as you settle in with the bumper. Thanks for all the feed back and info.

 

What other pictures/shots would you like? And no field notes, all the driving test I have done felt like it was the same, couldn't tell the difference with the bsm in comparison with the stock bumpe, same with cross traffic in reverse. I didn't even use it with reverse when I had the stock bumper cause im busy looking at the reverse camera.

I'll try to get you a pic of knife in hand asap. Imo I think it's a great bumper and worth the money. With everything I spent about $2500 with the bumper, linex, lights, road armor shackles, installation....and no complaints so far.

 

Looks like @BayRunner is 100% correct. The sides are acting as reflectors so no degradation.

 

Knife in hand, semper fi!

 

More pics

 

It’s hard to tell from the pics, but how much doesn’t the bumper stick out on the sides? The pic makes it look lime a good 2 inches.

 

Strange looking cake knife you have there...

 

Nah, maybe half an inch