Author: Christoph Bartneck

Simple LEGO Mindstorms Mars Rover

This is simple Mars Rover model using two LEGO Mindstorms EV3 and a total of eight motors. The two EV3 are daisy chained and the model can be controlled using the EV3 IR Remote Control. The model uses the rocker-bogie suspension system including a differential in the middle axis. The two EV3s are suspended and remain horizontal in any position. There are much more complex Mars Rover models already available using many more Mindstorm bricks. My design goal was to keep it simple and experiment with the rocker-bogie suspension system. The principles works, but there is a bit too much flexibility in the model.

The 3D model and the building instructions are available for LEGO Digital Designer. The parts list and instructions are also available at Rebrickable.

 

Nokia’s Body Cardio Scale Will Remove Pulse Wave Velocity

Since Nokia took over Withings the company continues to struggle with delivering good products. Today Nokia informed me that the Pulse Wave Velocity reading will be automatically deactivated and that there is nothing I can do to prevent this from happening. The reason they provide for the deactivation of this feature is that “it may require a different level of regulatory approval”.

While I agree that complying to the regulatory framework is a good idea, I wonder why they only considered this years after introducing the product. Why was this not part of their original design process? Regulatory frameworks vary considerably across the globe and Nokia decided to deactivate ALL scales. This does seem rather indiscriminate.

They offer a refund for the purchase price and they will then completely deactivate your scale. In their FAQ they do not mention the exact nature of the refund, but once you login into your account or followed their link you will find that:

I understand that I am eligible to be refunded for the purchase price of my product as shown on my receipt, less any fees that may have been incurred, including but not limited to: customs, duty, brokerage fees, shipping, or delivery costs. Nokia reserves the right to refund the local MSRP in lieu of this purchase price.

Again I have to wonder why there is no option for, lets say, half of a refund and you could continue to use the scale without the Pulse Wave Velocity reading. This all or nothing approach does not sit right with me since I do not want to throw away an otherwise fully operational scale but I also think that Nokia should reimburse us for the feature they are going to delete.

All of this is again an example of horrible product management and customer handling. The one feature that set this scale apart from their own Body+ scale is gone. I had an eye on their new Nokia Sleep tracker, but I do not want to go through this process of them screwing up their own products again.

Fonthill Abbey

We launched our Fonthill Abbey website on which we document our efforts to bring this amazing building and the story of its owner back to life. We created an interactive Virtual Reality Game that allows you to experience a forgotten piece of history as you become Lord Horatio Nelson or Lady Emma Hamilton, guests of mysterious Lord Beckford. You will have the rare privilege of entering secluded Fonthill Abbey and meet its extravagant owner, but will you make it out alive?

Comparison of color measurement accuracy of ColorMunki Design and FRU WR-10QC Colorimeter

Review of the measurement accuracy of the ColorMunki Design and the FRU WR-10.

I am working on a colour project and had purchased the WR10 colorimeter to complement my long serving work horse, the X-Rite Color Munki Design. My ColorMunki is already several years old and I was concerned that its accuracy might have declined. When I measured several hundreds of samples, I noticed that both colorimeters gave me considerably different LAB values.

To determine which device was closer to the truth I measured the 48 defined colours of Datacolor’s SpyderCHECKR 48. I calculated the absolute error both devices made. The results of a paired-sample t-test showed that the ColorMunki is producing significantly less measurement errors on L (t(47)=-9.229, p<0.001), L (t(47)=-4.590, p<0.001) and L (t(47)=-4.871, p<0.001). However, both devices measure colours that are significantly different from the target colour of the SpyderCheckr card on all three measurements. Figure 1 shows the means and standard deviation for all measurement errors.

Figure 1: Mean and Standard Deviation of all measurements for both devices.

There does seem to be some structure in the errors that WR-10 is producing. Have a look at the heat map (Figure 2). The data for my little experiment is available at the Open Science Framework (DOI: 10.17605/OSF.IO/UWEFD).

Figure 2: Heat Map of the absolute errors

Although both devices show some significant deviation from the original, it is not far off from what can be expected of devices in this price range. The ColorMunki Design produces significantly better results than the FRU’s WR-10QC.