As robot surgery becomes more widely implemented, the need to build a robot that more closely mimics the trained hands of a surgeon rises. As expected, much of this hinges on the right choice of robot components, such as robotic joints.
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What is Robot Surgery?
Long a facet of science fiction stories, the idea of robot surgey has become a reality over the past four decades. Surgeons are increasingly turning to robot-assisted surgery for aid in complicated and often risky medical procedures.
The use of programmable devices in surgeries to perform a wide variety of tasks is not intended to replace the human element of such procedures. Instead, robotic systems are used to assist and aid surgeons.
A surgical robot usually consists of a robotic arm, a manipulator, and a camera giving the operating surgeon a view of the patient from their remote control terminal.
Some of the benefits of robot-assisted surgery include allowing doctors to perform complex procedures with greater precision, flexibility, and control than conventional techniques.
Additionally, robotic-assisted surgery tends to be less invasive, involving smaller and more precise incisions, though the technique is also used in more traditional open surgical procedures. The benefits of this include fewer complications, such as surgical site infection, less pain, blood loss, shorter hospital stays and quicker recoveries, and smaller and less noticeable scars in the long-term.
Robotic surgery systems are now being employed in a range of procedures, from minimally invasive endoscopic surgery to complicated heart or brain surgeries.
Of course, perfecting robot controllers in surgical systems has required major advancements in technologies across a range of fields. This includes improving 3D cameras to give surgeons remotely controlling robots a better view of surgical sites, advancing control programs to ensure smooth movements, and granting robot arms the same steadiness as associated with a surgeon’s hand.
But perfected motion control and an excellent view are all pretty irrelevant without a robot arm being able to precisely move and flex. Thus, one major area of importance for advanced surgical robots is developing robot joint components that allow for flexibility in movement.
What are Robotic Joints?
Robotic surgery is still performed by a trained surgeon, albeit remotely. This means that robot components have to be able to replicate the precise hand movements of a trained human surgeon near-perfectly.
The easiest way of doing this is ensuring that the robot joints of surgical robots closely replicate the arm and hand of a human surgeon. Additionally, using small incisions for minimally invasive surgeries requires the application of small instruments, parts, and tools.
Robotic joints — also referred to as axes — are movable robot components that result in relative motion between the links — the rigid parts — of the machine. Optimal functioning for a robot arises from the correct balance of joints and links, while a manipulator
There are five main types of mechanical robot joints used in manipulators. These two types of translational joints — collinear and orthogonal joints — as well as rotational, twisting, and revolving joints, are all types of rotary robot joints.
Many mechanical surgical assistants are articulated surgical robots that are machines with different ranges and combinations of rotary robot joints. This can range from simple two-joint structures to more complex structures with up to 10 or more joints. In many articulated robots, the arm is connected to a base with the use of a twisting joint, while rotary joints connect the links in the arm.
Many systems put precision into practice in a robotic surgery platform. One example is CardioARM, a robotic surgical system having an articulated design providing unlimited but controllable flexibility. The CardioARM consists of serially connected cylindrical links housing flexible ports through which tools for both therapy and imaging can be deployed.
Another articulated robot component is the da Vinci Surgical System, which was introduced in China in 2008, leading to the development of the Micro Hand S, which provides an interesting case study for how such systems develop over the course of a decade.
Surgeons and the Robot Joint Design Process
One important factor of the Micro Hand S is the fact that actual clinicians have strongly influenced its development. This means its design takes into account actual problems faced by surgeons.
The initial robotic surgery system introduced in 2013 featured a rotational manipulator with three joints intersecting at the tip of the robotic arm. The design allowed for a large degree of freedom, enabling the operating arm to adjust automatically based on the incision procedure.
Three years later, a three-fingered robotic hand was proposed for the Micro Hand S to eliminate problems such as positioning prior to procedures and adjustment during operations. Later designs included a stacked design to make the surgical robot more compact.
Currently, the compact system with a foldable design of the Micro Hand S allows for a wide range of movement granted by three arm joints and three wrist joints. The range of movement from the arm joints is -120⁰ to 120⁰ and -30⁰ to 140⁰ respectively.
Designers have added instruments to the robot's components that facilitate ultrasonic or electro-cutting, electrocautery, and other functions and improve various safety features.
The master manipulator is comprised of three robotic joints (rotary), with the axes of the first two joints pointing upwards, so the robot’s motion is less affected by gravity, thus guaranteeing an easier and more flexible operation.
The practice of robotic surgery is only set to grow with surgeons guiding the design of systems they will increasingly use to improve and even save lives. And much of this will hinge on improved joints granting flexibility and precision.
References and Further Reading
Saber. A. Y., Marappa-Ganeshan. R., Mabrouk. A., [2022], ‘Robotic Assisted Total Knee Arthroplasty,’ StatPearls, [https://www.ncbi.nlm.nih.gov/books/NBK564396/]
Robotic surgery, Mayo Clinic, https://www.mayoclinic.org/tests-procedures/robotic-surgery/about/pac-20394974
Joint, Robotics, Britannica, [https://www.britannica.com/technology/joint-robotics]
Ota. T., Degani. A., Schwartzman. D., et al, [2009], ‘A highly articulated robotic surgical system for minimally invasive surgery,’ Pud Med, [10.1016/j.athoracsur.2008.10.026]
Bringing surgical insight to medical robot design, [2019], Nature Portfolio, [https://www.nature.com/articles/d42473-020-00175-z]
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