Using the center of gravity to help blind people measure water levels in bottles

People who are blind struggle to gauge water levels in bottles by weight alone. This work shows that combining information about a filled bottle's weight and center of gravity can enhance the accuracy of measuring the water level. Bumps were attached to the sides of cylindrical bottles at positions corresponding to the centers of gravity of water levels between 4 and 9. These bumps allow individuals to use additional information about the center of gravity to measure the water level in the bottle. Eight subjects who were blind participated in the experiment, and the results indicated that using the center of gravity method with a plastic bottle was the most accurate, with an average water level error of 0.04, but it took 57.83 seconds. Contrarily, using the weight method, the plastic bottle yielded the fastest results, with an average time of 6.51 seconds, but it led to an average water level error of 0.88.