A control for a crank shear that minimizes the RMS current

A motor driving a crank sees a nonuniform load. Thus, it is difficult to determine a minimal-energy strategy for controlling the crank. The minimal energy problem is formulated and solved for boundary conditions appropriate to a crank shear. Since this exact solution is difficult to implement in a control system, an approximate solution, based on a symmetric-ramp torque profile, is also presented. It was confirmed by experiments that this near-optimum velocity profile yields considerable savings in RMS current over the standard trapezoidal velocity profile