The palpator: an instrument for measuring the positions of bones in three dimensions

In order to measure the three-dimensional (3D) position of the shoulder girdle bones, as well as the 3D positions of muscle attachments and joint surfaces in cadaver experiments, a measurement instrument, called the palpator, was developed. The palpator is composed of an open chain of four links connected by four hinges. By recording the rotation of the hinges using potentiometers, the position of the end-point of the palpator can be calculated. After the identification of 23 parameters of the palpator, a measurement accuracy of 1.43 mm is obtained.