A system comprising: memory to store computer executable instructions and data; and a processor configured to access the memory and execute the computer executable instructions which comprise: a data aggregator to combine motion and position data from a plurality of sensors into an aggregate movement data describing multi-dimensional movement of a handheld device, wherein the handheld device comprises an active stylus, the plurality of sensors being integrated into the active stylus, wherein the plurality of sensors comprises at least two of a multidimensional accelerometer, a multidimensional magnetometer and a multidimensional gyroscope; wherein the plurality of sensors of the handheld device further comprises a displacement sensor configured to measure displacement of a moveable tip that extends from an end of the active stylus; a relative movement calculator to convert the aggregate movement data into relative movement data corresponding to a reference frame of a human machine interface, the human machine interface being separate from the handheld device; a pressure calculator being programmed to compute an indication of force corresponding to an interaction between the active stylus and the human machine interface based on the measured displacement, and a calculator to compute an indication of a movement disorder based on the relative movement data, the indication of force and user input data that is stored in the memory, the user input data being generated in response to user interaction between the handheld device and the human machine interface. memory to store computer executable instructions and data; and a processor configured to access the memory and execute the computer executable instructions which comprise: a data aggregator to combine motion and position data from a plurality of sensors into an aggregate movement data describing multi-dimensional movement of a handheld device, wherein the handheld device comprises an active stylus, the plurality of sensors being integrated into the active stylus, wherein the plurality of sensors comprises at least two of a multidimensional accelerometer, a multidimensional magnetometer and a multidimensional gyroscope; wherein the plurality of sensors of the handheld device further comprises a displacement sensor configured to measure displacement of a moveable tip that extends from an end of the active stylus; a relative movement calculator to convert the aggregate movement data into relative movement data corresponding to a reference frame of a human machine interface, the human machine interface being separate from the handheld device; a pressure calculator being programmed to compute an indication of force corresponding to an interaction between the active stylus and the human machine interface based on the measured displacement, and a calculator to compute an indication of a movement disorder based on the relative movement data, the indication of force and user input data that is stored in the memory, the user input data being generated in response to user interaction between the handheld device and the human machine interface. a data aggregator to combine motion and position data from a plurality of sensors into an aggregate movement data describing multi-dimensional movement of a handheld device, wherein the handheld device comprises an active stylus, the plurality of sensors being integrated into the active stylus, wherein the plurality of sensors comprises at least two of a multidimensional accelerometer, a multidimensional magnetometer and a multidimensional gyroscope; wherein the plurality of sensors of the handheld device further comprises a displacement sensor configured to measure displacement of a moveable tip that extends from an end of the active stylus; a relative movement calculator to convert the aggregate movement data into relative movement data corresponding to a reference frame of a human machine interface, the human machine interface being separate from the handheld device; a pressure calculator being programmed to compute an indication of force corresponding to an interaction between the active stylus and the human machine interface based on the measured displacement, and a calculator to compute an indication of a movement disorder based on the relative movement data, the indication of force and user input data that is stored in the memory, the user input data being generated in response to user interaction between the handheld device and the human machine interface.