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deeper-blue / sdp-robot

The robot code for Deeper Blue, an assistive chess-playing robot. Developed for the System Design Project, a 3rd year course offered at the School of Informatics, University of Edinburgh.
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Decrease Platform error #36

Closed pilif0 closed 5 years ago

pilif0 commented 5 years ago

Based on Demo 2 QA (move 30 cm), there is an average error of -1.30 cm in the actual distance moved and +0.02 cm (<1 degree) in the perceived distance moved. The perceived distance is close enough for our purposes. But the -1.32 cm difference between reality and how far the motor thinks it has moved should be improved.

The data would suggest that the main problem is in converting the linear distance into rotation of the motor, because the desired rotations were carried out but the distance was not reached. Therefore the problem is probably in the conversion calculation (angle = distance / circumference * 360), probably with the wheel circumference constant (as that is the only variable in the equation). The test distance was 30 cm and with wheel circumference of 12.8 cm, resulting in 843.75 degrees of movement (2.3438 rotations). The actual distance of 28.7 cm would instead correspond to a circumference of about 12.25 cm over the same 2.3438 rotations.

Changing the platform wheel circumference constant might lead to a decrease in the error.

pilif0 commented 5 years ago

There was an error with the QA we did for Demo 2, or with the motor being used then. I redid the QA and got a fairly consistent average of 29.3 cm (st. dev. 0.03).

Based on the new QA, I calculated the new circumference should be 12.53 cm.

This change resulted in the average distance travelled being 30.0 cm with st.dev. of 0