A method for tracking movement of a person, comprising: arranging a plurality of sensors of a motion tracking system on a body of the person, the plurality of sensors at least comprising first and second sensors each at least comprising an accelerometer and a gyroscope, wherein the first sensor is arranged on a first body member of the person, the second sensor is arranged on a second body member of the person, the first and second body members (51, 52) being connected by a first joint; and tracking movement of the person with the plurality of sensors at least while the person performs a movement; characterized by: digitally estimating, with a computing device, a position of either the first joint or the sensor on the second body member, wherein the position of the first joint is estimated using both measurements of the first sensor and a first predetermined length, and the position of the sensor is estimated using measurements of both the first sensor and the sensor arranged on the second body member and further using both the first and a second predetermined lengths, and wherein the position is estimated while movement of the person is tracked; digitally computing, with the computing device, an acceleration of the estimated position while movement of the person is tracked; digitally computing, with the computing device, a first comparison between the computed acceleration of the estimated position and acceleration measurements of the sensor arranged on the second body member; and digitally determining, with the computing device, the movement performed by the person based on the first comparison. arranging a plurality of sensors of a motion tracking system on a body of the person, the plurality of sensors at least comprising first and second sensors each at least comprising an accelerometer and a gyroscope, wherein the first sensor is arranged on a first body member of the person, the second sensor is arranged on a second body member of the person, the first and second body members (51, 52) being connected by a first joint; and tracking movement of the person with the plurality of sensors at least while the person performs a movement; characterized by: digitally estimating, with a computing device, a position of either the first joint or the sensor on the second body member, wherein the position of the first joint is estimated using both measurements of the first sensor and a first predetermined length, and the position of the sensor is estimated using measurements of both the first sensor and the sensor arranged on the second body member and further using both the first and a second predetermined lengths, and wherein the position is estimated while movement of the person is tracked; digitally computing, with the computing device, an acceleration of the estimated position while movement of the person is tracked; digitally computing, with the computing device, a first comparison between the computed acceleration of the estimated position and acceleration measurements of the sensor arranged on the second body member; and digitally determining, with the computing device, the movement performed by the person based on the first comparison. digitally estimating, with a computing device, a position of either the first joint or the sensor on the second body member, wherein the position of the first joint is estimated using both measurements of the first sensor and a first predetermined length, and the position of the sensor is estimated using measurements of both the first sensor and the sensor arranged on the second body member and further using both the first and a second predetermined lengths, and wherein the position is estimated while movement of the person is tracked; digitally computing, with the computing device, an acceleration of the estimated position while movement of the person is tracked; digitally computing, with the computing device, a first comparison between the computed acceleration of the estimated position and acceleration measurements of the sensor arranged on the second body member; and digitally determining, with the computing device, the movement performed by the person based on the first comparison.