[kdawg]

Using my cruise control today, I could not get it to set to 62mph. If I hit up, it went to 63. If I hit down, it went to 61.

Anyone else experience this?

Is this a software glitch, or by design? (first I've experienced it)



EDIT: just ran across this forum post. Looks like the 2012's were doing the same thing as my 2013 is now.
http://gm-volt.com/forum/showthread.php?18765-Cruise-control-set-to-0-mph

 

[Mathew Hennessy]

I've seen this quite a bit in my 2011, 69/71 . Methinks there's some rounding error in their software. Haven't seen it in my 2013 yet.

 

[cmr]

both of my 2012's occasionally do it. when it goes to 63 walk it up to 65 and then walk it back down to 62 one mph at a time and it will usually take. if all else fails disengage it and reengage at the speed you want.

 

[oolowrideoo]

The Cruze ECO I owned before the Volt did the same thing... Drives OCD engineers like me nuts.

 

[Chevrolet Customer Svc]

Using my cruise control today, I could not get it to set to 62mph. If I hit up, it went to 63. If I hit down, it went to 61.

Anyone else experience this?

Is this a software glitch, or by design? (first I've experienced it)



EDIT: just ran across this forum post. Looks like the 2012's were doing the same thing as my 2013 is now.
http://gm-volt.com/forum/showthread.php?18765-Cruise-control-set-to-0-mph

Good Morning Kdawg,

The cruise control, and vehicle speed, is based off of the output shaft angular speed. It is translated to kilometers per hour to several decimal places and used in multiple controllers on the vehicle. The displayed vehicle speed on the instrument cluster is truncated, rounded, and actively filtered for the driver to have an easier time reading the speed. When you first set your cruise control, several controllers use the exact value to set your speed. As you tap up and down the speed from your set-point, there can sometimes be rounding error in the display depending on the original set-point. So in your example, tapping up would show you the low side of 63, but tapping down would show you the high side of 61. You can always cancel cruise and choose another exact set-point for the purposes of the display, but the multiple controllers involved are still obeying your original command despite what the instrument cluster is displaying.

The summary here is that the car is much more advanced than the human interface displays are showing. I hope this answer the questions as to what you were experiencing!

-Ian Chevrolet Volt Customer Service

 

[gilzapanta]

The exact same thing happened to me twice so far and I never thought anything of it as I figured the computer was just doing what it does. The first time it hapened was 2 months ago to this day (weird that this comes up) and the other time it happened was about 3 weeks later. It has not occured again since then so I am hoping it was just a fluke! Other than that, this car is fantastic.

 

[cmr]

Good Morning Kdawg,

The cruise control, and vehicle speed, is based off of the output shaft angular speed. It is translated to kilometers per hour to several decimal places and used in multiple controllers on the vehicle. The displayed vehicle speed on the instrument cluster is truncated, rounded, and actively filtered for the driver to have an easier time reading the speed. When you first set your cruise control, several controllers use the exact value to set your speed. As you tap up and down the speed from your set-point, there can sometimes be rounding error in the display depending on the original set-point. So in your example, tapping up would show you the low side of 63, but tapping down would show you the high side of 61. You can always cancel cruise and choose another exact set-point for the purposes of the display, but the multiple controllers involved are still obeying your original command despite what the instrument cluster is displaying.

The summary here is that the car is much more advanced than the human interface displays are showing. I hope this answer the questions as to what you were experiencing!

-Ian Chevrolet Volt Customer Service

that was a great explanation, thanks for posting it.

 

[kdawg]

Thanks for the detailed response Ian. For feedback to the engineers I'll have to think about a solution, if one is really needed, (possibly adding a decimal point would do it). I know some here would suggest pseudo analog gauges, but personally I prefer the digital ones. Not sure if the software can be written so that 1 click always equals 1 mph on the setpoint, but maybe another interface would work better (voice command(not sure of the law on this), or a rotary dial). Has any thought been put into adaptive cruise control?

 

[deekster_caddy]

Ian's response is spot on and agrees with my experiences - if I am using CC on a side street I can generally set it as low as 25 mph, but sometimes if I do things just right I can set it to read 24 mph, and it all depends on exactly where I catch it when setting the Cruise speed.

 

[NoRegrets78]

Always wondered why my 13 did that sometimes. Glad to know there's not a real "bug" or anything.

 

[Mathew Hennessy]

Always wondered why my 13 did that sometimes. Glad to know there's not a real "bug" or anything.

A rounding error counts as a bug, even if it's non-critical and there are workarounds.. Man, I wish GM had a customer-facing Bugzilla, JIRA, etc. for their software the way, say, Ubuntu does..

 

[kns]

A rounding error counts as a bug, even if it's non-critical and there are workarounds.. Man, I wish GM had a customer-facing Bugzilla, JIRA, etc. for their software the way, say, Ubuntu does..

Outstanding suggestion!!

Would not only provide GM with info on what drivers find annoying but would also enable drivers to easily learn whether or not a particular behavior has been reported, whether or not it is expected and, if not expected, whether and when a 'fix' or workaround suggestion might be forthcoming.

KNS

 

[Joule]

I've seen this a few times in my 2013. Great question, great response from Ian. Thank you.