CAN interface for 3D MEMS force sensors

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Dr. Tóth Csaba
Department of Measurement and Information Systems

As part of a bigger research project at the Hungarian Academy of Sciences - Institute of Technical Physics and Materials Science, the research team I joined has been working on developing a 3D MEMS force sensor for medical applications. Pairs of these force sensors are to be implemented in laparoscopes used for medical operations. The laparoscopes are part of a bigger medical robot’s system.

It was my task to build a communicational bridge between the sensors, the medical robot, and the outside world. The 3D MEMS force sensor’s analogue voltage is sampled by an ADC. The data acquired by the ADCs will be sent to a microcontroller on an I2C bus. The microcontroller will forward the data on a CAN bus. The microcontroller periodically reads out the data from the ADCs and preprocesses the data before sending it out to the CAN bus. The microcontroller must be able to accept CAN messages as well. In the received CAN messages, the microcontroller receives the constant parameters that are needed for preprocessing the accumulated data. The microcontroller must also be able to save the constants in a non volatile memory.

My paper describes my design work which can be summarized in the following points:

• I described the medical robot’s desired behavior, and explained the function of the laparoscope inside the system.

• I presented the 3D force sensors, and defined the specifications necessary for designing the microcontroller based system and CAN communication.

• I designed the system layout for a microcontroller based CAN driver, picked out the necessary parts, and designed the system.

• I prepared the CAN driver on a breadboard level and demonstrated the workings of the system.


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