A Helping Hand

Zhengyang (Kris) Weng

The gentle notes fill the air as Zhengyang (Kris) Weng (MSR '25) sits at the piano, his fingers dancing across the keys. For 20 years, Weng has honed his musical skills, marveling at the intricate movements of the human hand.

Now, as a robotics engineer, he is attempting to recreate that same dexterity in a machine.

Weng's winter quarter independent project in Northwestern Engineering's Master of Science in Robotics (MSR) program focused on developing a robotic hand that mimics human capabilities. The project, which he calls the Biomimetic Dexterous Hand (BiDexHand), showcases the complexity of human anatomy and the challenges of replicating it.

With 27 degrees of freedom packed into a compact space, the hand is a marvel of natural engineering.

“Human hands are actually incredible. They are so incredible that you really don't notice them because they're just very natural to use,” Weng said. “They can do very powerful moves. You can hammer with them, you can pinch with them, but you can also do very delicate tasks.”

The BiDexHand uses a cable-driven mechanism to replicate the intricate muscle structure of the human hand and forearm. Weng repurposed fishing wire as cables and relocated the actuators to the “forearm” region of the robot, mirroring human anatomy.

Weng faced difficulties integrating so many degrees of freedom into a similarly sized robotic counterpart. He ultimately redesigned the hand’s cable routing structure after encountering issues with joint control and fine movements.

In just 10 weeks, he also:

• Used computer vision and machine learning algorithms to help the hand mimic human gestures
• Created a virtual reality (VR) app so the hand could be used for VR experiences
• Integrated the hand with a robotic arm so it could be used for more complex tasks
• Designed a wrist camera as part of the hand-arm integration so that the hand can perform vision-based tasks and interact with the environment more effectively
• 3D-printed all of the parts for the hand

Weng’s MSR coursework proved invaluable during the project. He applied knowledge from classes on embedded systems in robotics and kinematics analysis to integrate the hand with a robot arm and create a motion planning package.

He said he sees direct applications for his research.

“A lot of surgical robots are actually cable-driven, more on the tools and instrument side,” Weng said. “I wanted to get familiar with this space, and this definitely helps me professionally.”

As the project wrapped up, Weng saw potential for further development.

“My ultimate goal for this project is really to mount this hand on a robot arm and have it play the piano with me,” Weng said. “I think that's going to be a very cool demo of human-robot synergy and interaction.”