Platform 3: Actuation & Control

Principal Investigators

Professor Peter Xu, University of Auckland
Associate Professor Andrew Taberner, University of Auckland

Associate Investigators

Dr Bryan Ruddy, Associate Professor Leo Cheng (University of Auckland), Dr Martin Stommel (Auckland University of Technology)


Rahman Hashen, Yu Dang, Nick Do, Jiali Xu


Many problems in medicine and health need innovative actuators, together with their associated control systems. The purpose of the Actuation and Control technology platform is to develop and provide solutions that can support the goals of the existing flagship projects, but also to progress the platform through the development of new actuators, methods, and control systems. Our initial efforts are spread across two areas and classes of actuator: Large deformation peristaltic actuators, and linear electromagnetic actuators:

1. Large-deformation Peristaltic Actuators

Large deformation actuators can be used to simulate biological functions such as peristaltic motion and the interaction of internal organs such as the esophagus, stomach, intestines and heart. In this project a motor inspired by the principles of the muscular hydrostat will be used to test the performance of different catheters (sizes, shape, flexibility etc), to validate clinically significant hypotheses, and to examine the flow of organ contents. Mechatronic design principles will be applied in developing the bio-robotic actuation system. Novel drives (such as PneuNet technique) and control methods (such as data-driven learning control) will be developed to make the actuator useful for various medical purposes.

A diagram of the human digestive system with the following organs labelled from top to bottom: mouth, tongue, oesophagus, stomach, duodenum, small bowel, large bowel, rectum and anus.

We also plan to develop a theoretical foundation for the dynamics and control of soft-bodied robots comprising nervous units, actuation, sense and skeletal functions embodied in a single body. Irrespective of the form of drives and materials used, they will be soft and deformable, actuated, sensed and controlled in distributed manner, and of a potentially infinite number of degrees of freedom.

The research questions for soft-bodied robotics include how to describe the motion of such a robot (forward problem), find the actuation required for the prescribed motion (inverse problem), generate the distributed actuation (motion planning) and accomplish the required actuation (control problem).

2. High-efficiency Voice-Coil Motors

Voice coil motors are fast, simple, and robust linear actuators that until now have offered only modest force capability which has limited their biomedical applications. In this platform we are developing new designs for these actuators and their controllers that allow extremely high forces to be applied for a short period of time, suited to a wider range of tasks that includes drug delivery. Our goal is to develop new applications for these actuators in medical devices, to develop new strategies for their design optimization suited to medical applications, and to refine and enhance the control strategies used to ensure their robust and reliable performance.

See caption.

Components of a linear voice-coil motor; Drug delivery device using linear voice-coil motor

3. High-efficiency Linear Synchronous motors

Linear synchronous motors are flexible, powerful, and efficient actuators that have seen little use to date in biomedical applications. As shown here, they are composed of periodic arrays of magnets and coils, which means that their design can easily be scaled to the needs of the application. A compact, water-cooled motor designed for robotic locomotion is also shown. We are working to apply these actuators to drug delivery and rehabilitation robotics, developing motor designs optimized to each task along with compact, self-contained motor controllers. For example, we show a preliminary design for a lower-limb exoskeleton powered by a set of linear synchronous motors. Our goal is to create plug-and-play actuator systems for these new applications, and to examine the performance of these systems, as well as the overall medical device performance enabled by the new motors.

A composite image of an actuator with a piston, next to a cylinder, next to a lower-limb exoskeleton.