Direction Priority Control Method for Magnetic Manipulation System in Current and Voltage Limits

Magnetic manipulation system generates a magnetic field and gradient so that it can control the position and attitude of the microrobot, a magnetized agent of size under 1 mm. The system generates the force, torque, and magnetic field with currents. To date, no adjustment method concerned with voltage and current limits for the current controller of the system is researched. This paper proposes a control method that multiplies a ratio with all current or voltage references, making the largest one bounded to the rated value. Modified force, torque, and magnetic field commands are scaled down from the original ones keeping the same directions, respectively. Such adjustment may degrade the control performance but helps to control the position and attitude of the microrobot without distortion. Detailed adjustment steps considering gravity compensation and voltage feedforward terms are proposed. Simulative and experimental comparisons between two reference adjustment methods are done.