Few months back, Moto labs posted results of a simple test – which basically consists of using a basic drawing application and a finger to slowly trace straight lines on the touchscreen of each smartphone. The test clearly showed that iPhone’s touchscreen offered higher degree of sensor accuracy compared to devices like HTC Droid Eris, Motorola Droid and Google Nexus One. However, few critics faulted human finger methodology calling it prone to inconsistency, due to variables in finger pressure, line-straightness or tracing speed.

Moto labs have now posted results of second test done by using robot to rule out the above-mentioned inconsistency. Moto wrote a script for their laboratory robot and then re-ran the comparison to see how the touchscreens stack up when the line are drawn by their robot’s slow and precise “finger”. The video below shows the test in action.

Moto labs also added two new contenders Palm Pre and BlackBerry Storm 2 to the test lineup.  The test was performed once with 7mm finger for medium touch input and then with 4mm finger to replicate very light touch input. The new test methodology improved the accuracy of the test, but the results didn’t change much. Moto wrote, “The iPhone still retains its crown as king of the smartphone touchscreens, with Nexus One in a distant second.”

All smartphones performed better in 7mm medium touch input test than on 4mm very light touch input test. In both the tests Motorola Droid and BlackBerry Storm 2 were the worst performers followed by Palm Pre and HTC Droid Eris.

The test shows the amount of time and effort Apple has put in development of both the software and the hardware for iPhone. It also shows why most critics and consumers consider iPhone the best touchscreen device on the market.