Contact Force and Torque Estimation in Robots

07 July 2022

Recent PhD graduate Feng Cao advances research in contact force and torque estimation for the use in robotics.

  • Feng PhD thesis2
Feng PhD thesis

PhD graduate Feng Cao

The UC Mechanical Engineering Department would like to congratulate Feng Cao for his successful PhD viva defense.

Feng’s research investigates contact force and torque estimation in industrial serial robotics. Robots used in commercial applications rely on a measurement of physical contact force to appropriately operate within their environment. These measurements are traditionally achieved by means of physical contact force and torque sensors, which can be quite expensive. For example, a physical sensor for an ATI industrial robot can cost upwards of NZD 20,000.

To help alleviate the extensive costs associated with these sensors, Feng has set out to investigate more economical solutions. Feng describes how he “ found that if the payload on the robot changes, the motor current will change. I use the motor current to estimate the contact force and torque on the robot”.

Feng’s approach is an elegant solution by implementing existing measurable data from the operational functionality of a robot and repurposing that information to serve a new task. To help assess the nuances involved in this application, Feng has illustrated leading components of his research with his recent publication, Contact force and torque sensing for serial manipulator based on an adaptive Kalman filter with variable time period, in Robotics and Computer-Integrated Manufacturing.

Feng introduces a mode-switching moving average with a variable time period to reduce the effects of measured motor current noise, providing improved confidence in joint output torque estimation. Feng demonstrates force and torque estimation without force/torque sensors by coupling this proposal with an adaptive Kalman filter.

We are pleased to share these advancements being made by Feng and wish him the best in any future developments he makes. Feng has enjoyed his time in Christchurch and hopes to stay and work here for the foreseeable future.


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