Improving contouring accuracy by tuning gains for a bi-axial CNC machine

Improving CNC contouring accuracy by robust digital integral sliding mode control

“…2, it is noted that the steady-state error for the linear contour is 121:2 μm and that for the circular error is approximately a sinusoid with a magnitude of 122:3 μm. The significant steady-state errors show clearly the effect of unmatched dynamics [23]. With matched axial dynamics the steady-state error for the linear contour should be zero and that for the circular contour a constant and far smaller value indicating a resulting circular contour with a radial error.…”

“…By including estimates of the disturbances and integral control action into the controller, the system dynamics are controlled to slide along a pre-designed sliding surface, thereby achieving a predefined dynamic performance. By using the same model of the sliding surface for both the X-and Y-axes, matched axial dynamics can be achieved leading to improved contouring accuracy [22,23]. ISMC has also been reported in fast servo diamond turning [24,25].…”

Improving contouring accuracy by using generalized cross-coupled control

“…Poo et al [4] and Xi et al [5] showed that axial following errors can lead to significant contour errors when the axial dynamics are not properly matched. Through analysis, simulation and actual experimentation, they showed that even with significant axial following errors, these can be made to cancel each other out to achieve perfect contour following with no contour errors when the axial dynamics are properly matched.…”

Cascaded proportional–integral–derivative controller parameters tuning for contour following improvement

“…And the controller was of high-order structure with a digital disturbance, which required open programmable hardware and thus was not easy to be realized in commercial servo systems. Xi et al 43 proposed a cascaded PID parameters tuning method for bi-axial machine based on considering the axis dynamics as a linear first-order model. It first analyzed the contour performance based on final value theorem and concluded that only the position loop P controller parameter influenced the steady contour error under constant speed path.…”