Micro-Domain Force Estimation Using Hall-Effect Sensors for a Magnetic Microrobotic Station

This paper introduces a novel micro-domain force estimation method for applications in a magnetic-haptic micromanipulation platform (MHMP). The MHMP employs the magnetic levitation technology in micro-domain worlds for ultra-high precision micromanipulation. In the MHMP, a microrobot that consists of a magnetic head and a body that includes electronic parts and an end-effector is manipulated by regulating an external magnetic field. The MHMP has been equipped with a haptic technology to allow a human operator to feel micro-domain environments and to intervene in dexterous tasks due to the poor knowledge from micro-worlds. To preserve a high feeling of a micro-domain environment for a human operator, the applied force/torque from the environment to the microrobot are required to be directly measured by specific sensors. Due to the size restriction, attaching force sensors to our microrobot is impractical. Therefore, we use a combination of Hall-effect sensor in the structure of the MHMP to estimate a single-axis force, eliminating the need for sensors on the microrobot. The Hall-sensors measure the magnetic flux and determine the location of the horizontally zero magnetic field gradient, Bmax location. It was realized that the applied force from the environment to the microrobot is linearly proportional to the distance of the microrobot from the Bmax location. The magnetic force which is equal to the environment force is calibrated using a cantilever deflection. The developed micro-domain force estimation method is verified experimentally, and it was demonstrated that this method has promising potential in estimating the environmental force applied to the microrobot in a non-contact way.