This article was first published on Computer Vision News of June 2022.
Michael Brockdorff is a second-year PhD student at the University of Leeds. Giovanni Pittiglio is a research fellow at the Harvard Medical School and Boston Children’s Hospital. Their paper on a dual-arm platform for control of magnetically actuated soft robots has just won the Best Paper Award at CRAS 2022, and they are here to tell us all about it.
Devices used in bronchoscopy are generally rigid and thick, limiting how deep clinicians can get into the lungs and potentially causing damage and discomfort to patients as they bend the tissue around them. Clinicians use a pre-computed anatomy map, often from a CT scan, which is less helpful once they insert the rigid tool and the anatomy moves.
In this work, Michael and Giovanni propose using soft silicone-based magnetic catheters inside the body controlled externally by two permanent magnets on robotic arms, allowing for precise control of the magnetic field in the workspace. This contactless form of actuation means devices can be smaller and reach areas of the lungs that are impossible to reach with classic tools. The soft devices will bend and conform to the body during navigation, so they will not deform the anatomy, removing any pain or discomfort for the patient and leading to a better-targeted intervention.
“This unique platform combines a large workspace – the human body – with high magnetic fields and a high degree of manipulability,” Giovanni tells us.
“When you actuate the magnetic field within a large workspace, the main difficulty is actuating strong magnetic fields with a high level of controllability. With one permanent magnet, you can control five degrees of freedom. We add three more degrees of freedom, up to eight degrees, with two magnets. That is a key part of this platform compared to smaller actuation systems.”
Professor Pietro Valdastri from the University of Leeds had the initial idea of actuating these devices to conform to the anatomy with multiple magnets along the length of the catheter. But the team discovered that if this was not matched with the ability to control the magnetic field in a more convoluted way, the degree of shaping does not improve. The team met with Pietro’s colleagues from the University of Toronto, who were working on the ability to control the magnetic field in a more convoluted way with eight degrees of freedom, but within a relatively small magnetic workspace, which did not apply to their case.
How did they solve it?
“Two years of hard work!” Giovanni laughs.
“I thought, what if we take that idea of being able to control these degrees of freedom and we scale it up. The way to scale it up usually is to use permanent magnets with systems of coils, but the energy consumption and need for cooling make that very costly. We started investigating mathematically and theoretically – what can one, two, three, or more permanent magnets do? Luckily, we stopped at two because I don’t think Pietro would have paid for ten robots!”
Michael adds:
“We’re exploring the possibility of using more robots in the future, but we have already maximized how much we can control the magnetic field in our workspace with this platform. More robots might allow the development of new devices that we haven’t even thought of yet, but we’re focusing on our two-robot system for now.”
Being picked for a Best Paper Award is a huge achievement and no mean feat, but Michael has an idea of what might have influenced the judges’ decision.
“I like to think it’s the novelty and diversity of our platform,” he tells us.
“Compared to most actuation systems, the bigger workspace we offer with our dual-magnet approach makes it easier to step into the medical field but is versatile enough to be used for a whole range of magnetic devices, including in the medical domain and beyond.”
Looking to the future, Giovanni thinks it is essential they focus on the clinical need.
“We’ve done a lot of technical work in the last three years with this project, so having a strong clinical application sooner rather than later, before moving on technically, could be a good step forward.”.
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