Researchers from the Indian Institute of Technology Gandhinagar (IITGN) have proposed the concept of virtual actuation space (VAS) for Tendon-driven Continuum Robots (TDCRs). This framework can handle multiple sections of a robot with ease, significantly reduce computational demands and improve tracking precision. Their findings were recently published in Robotica.
We often imagine robots as machines with rigid arms, rotating joints and targeted mechanical
movements. However, such robots would be unable to function in confined and cramped
environments. Imagine trying to perform a surgery inside the human body. It would be
challenging because of the presence of delicate organs and soft tissue. Stiff robots would not be
able to navigate such places without causing damage, as they would require larger openings to
move around.
Enter continuum robots (CRs) with flexible bodies to effectively navigate cluttered spaces! The
tendon-driven continuum robot (TDCR) is a type of CR known for its compact, lightweight
design, precise control, and cost-effectiveness. It has thin wires (tendons) that help it to smoothly
and accurately bend in different directions. The tendons are attached along a flexible backbone,
and when pulled, appear to mimic animal appendages to create the required motion.
However, predictions involving TDCRs are challenging. “While a rigid robot may have a fixed
number of joints that would limit its movement, a TDCR can bend in infinite ways. The situation
is further complicated by its multiple sections,” explained Dr Madhu Vadali, Associate
Professor, Department of Mechanical Engineering, who co-heads the IITGN Robotics Lab.
The VAS proposed by IITGN researchers is a step towards solving this problem. It imagines a
simple representation of the robot’s motion instead of directly controlling its physical tendons
and enables independent control of its individual sections. This feature reduces the complexity of
controlling multi-section robots.
According to Md Modassir Firdaus and Dr Shail Jadav, “To estimate this method’s effectiveness,
we developed a robotic arm with two sections having six tendons. Small LED markers allowed a
camera to track the robot’s position. Later, a computer compared the actual position with the
robot’s desired position and adjusted the attached motors accordingly.” While Mr Firdaus is a
PhD scholar in the Department of Mechanical Engineering, Dr Jadav is a former PhD scholar in
the same department. Currently, he is a postdoctoral research fellow at the Technical University
of Vienna.
The error margin for movement in experimental tasks was less than one per cent, highlighting
remarkable precision. Further, the two sections of the robot could operate independently based
on the situation. To understand it better, imagine moving one’s fingers while keeping one’s wrist
straight and then doing the opposite.
In essence, the VAS framework can significantly improve the accuracy of TDCR. The scalability
of this method extends to TDCRs with additional sections, opening doors to practical
applications, such as surgeries, industrial automation and confined-space inspections, like in
aircraft engines.
This study aligns with India’s National Strategy on Robotics, which aims to position India as a
global leader in robotics by 2030. It builds upon Make in India 2.0, which identified robotics as a
sub-sector to enhance the country’s integration in the global value chain. In the words of Dr
Vadali, “At IITGN, we have built an enthusiastic and engaging culture surrounding robotics.
Robotics is becoming a domain where curiosity drives cutting-edge and societally-relevant
innovation”
The researchers have filed a patent (number 202421002550) related to this work with the Office
of the Controller General of Patents, Designs and Trade Marks, Government of India. They
acknowledged the Gujarat Council on Science and Technology for providing financial support.
They also acknowledged feedback from the IITGN Robotics Lab team.