Improvement of Force Sensor Accuracy Using Redundant Outputs for Biomedical Applications

While strain gauges are commonly used in a force sensor, we used multiple digital Hall-Effect magnetic sensors for developing a three-dimensional force sensor. We are aiming to develop a round shape three-dimensional force sensor. In order to get three-dimensional unknown force components, three independent outputs from the sensor are at least necessary. Four or more outputs however, would not be useless but redundant data sets, which could be useful to improve sensor accuracy. We calculated the unknown three-dimensional force values using nine outputs or less and estimated how many redundant outputs we should use to get good accuracy. As a result, when three outputs were used, the sensor accuracy was ranging from 8.2 to 15.7% depending on which outputs were used. When six outputs were used, the sensor accuracy was ranging from 5.5% to 5.6%. When nine outputs were used, the sensor accuracy was 4.1%. Although the best accuracy was acquired when we used all nine outputs, improvements were minimal when we used six or more outputs.