Disturbance observation control with estimation of the inertia matrix

Disturbance observation control (DOC) is an effective technique for controlling mechanical plant in the face of internal and external disturbances. By adding transducers to measure the controller input and the plant output it is possible to obtain an indirect measure of the total disturbance. This may be fed forward to effect cancellation. To obtain the best performance it is necessary to have a good estimate of the plant inertia matrix, but unfortunately this is often not available. Here we present a method for obtaining an estimate of the inertia matrix which is amenable to optimisation. By the use of a “probing input” a measure can be obtained of the accuracy of the estimate. This may be updated, either continuously or periodically so as to drive the estimate closer and closer to the actual value.