Medical robots comprise a variety of technical apparatuses and machines employed in the medical field either to perform work of a mechanical nature or to assist in such activities. Until recently still fiction, they are now found in everyday use in many hospitals, clinics and  rehabilitation centres, where they have become indispensable. As reliable assistants, medical robots perform tasks that go beyond the capabilities of human beings as well as others that surgeons, nurses and doctors of internal medicine are simply unable to fulfil. An important factor in this respect is the onset of fatigue in humans in the course of extensive surgical operations. Driven by innovation and their great relevance in society, the numbers of approved medical robots in use on a global level is growing, enabling the field of medical engineering in general to open itself up to further fields of application.

Components and function of medical robots

Thanks to the breadth of scope of modern robotics, medical robots can be equipped with a wide and highly varied range of specially produced components, and they also differ in terms of their size, form and construction. However, their fundamental modules generally comprise a controller unit and a manipulator. The latter is usually in the form of a robot arm that is designed to perform actions, and consists of jointed segments, sensors, a drive system and the so-called effector.

Depending on the area of application in which the medical robot is employed, the effector can be compared with a gripper arm and represents the link between the robot and its environment in that it executes commands. While electrical drive technology is generally employed, the quantity of segments and joints depends on the respective application. The sensor system is not only responsible for determining the manipulator’s position but it also collects various types of data, such as distances and camera images and feeds it to the robot’s controller.

The way a medical robot is controlled depends primarily on the context in which it is used. In surgical operations, the surgeon actively operates the robot. Movements made with consoles, joysticks or other similar control elements are performed synchronously by the robotic arm (telemanipulation control). If the robot is required to perform certain movements autonomously, they must be manually programmed in advance or described by way of offline programming.

Development of medical robots over time

The history of medical robots goes back about 25 years, which makes them a relatively recent achievement of medical engineering. However, since their inception, the field of robotics in medicine has quickly established itself and is now indispensable in many applications. The rapid developments and veritable euphoria surrounding the use of computer-controlled  processes and robots in the field of medicine are due first of all to the positive experience made with imaging technologies such as X-ray diagnostics, computer tomography and endoscopy. In addition, innovations in the field of processors and data storage have been an important factor influencing the advancement of medical robots, as the employment of arithmetic logic units has enabled the synchronous processing or use of large amounts of data. Another important factor is that the acceptance of robots in medicine by society is on the increase; a general shift in thinking has a positive effect on the advancement of the respective systems.

The first time a medical robot was used to assist in a surgical operation was in 1991, when a transurethral resection of the prostate (an interventional urological technique for diseased tissue) was performed; this was quickly followed by several further procedures. In Germany too, the use of robots became widespread, and it was not long before medical robots were assisting in bone surgery. The ongoing transformation can be observed today more clearly than ever: the presence of innovations and the constant advancements are evidenced by the numerous systems and devices in the field of robotics that are awaiting approval.

Precision in space and time - aims and characteristics of medical robots

In contrast to the impressions sometimes given in fictitious depictions, robots are not employed in technical medical environments with the aim of fully ousting human employees. Medical robots primarily perform an assisting role, in which they are regarded as a helping hand or an extended arm. They offer a finely nuanced selection of applications and procedures, and they can be specially configured to perform certain processes with great precision and simplicity. Medical robots, or more specifically their active arm element, are sometimes referred to as manipulators, as they principally do not act independently but always under the control of a human operator. In this way, the technology represents a positive manipulation or optimisation of human abilities.

The main advantages and elementary characteristics of medical robots are brought to bear in minimal invasion procedures. Their constant level of work performance serves to shorten the duration of operations and in turn reduce the stress on the patient and decrease the incidence of treatment errors brought about through tiredness. Actively controlled medical robots can be operated remotely, where required, using a console. This means that the surgeon does not have to stand directly at the operating table but is able to control the system from a distance of a several metres. Moreover, robots are of course immune to any mental or emotional impulses, which enables them to work with great precision, both from a spatial and a temporal perspective.

The ability of medical robots to work with great precision is of particular importance in minimal invasion procedures, which are based on the use of very small incisions. Such systems are capable of scaling down movements performed by the doctor and converting them to minimal actions. For example, a movement of one centimetre on the control element can translate to a distance of one millimetre on the patient’s body.

Summary of the advantages of medical robots

  • Constant level of work performance
  • Not influenced by mental impulses
  •  Great spatial and temporal precision
  • Can be operated from a distance where required
  • Extend the range of possible treatments 

Areas of application of medical robotics

The application spectrum of medical robots in the operating theatre is already highly varied. They are particularly useful in surgical environments and their various specialist disciplines, such as orthopaedics, plastic surgery, and heart surgery. However, robots are also employed in medical contexts outside the operating theatre. Specialised medical robots can be used for transporting blood reserves or for bottling samples. Others are able to perform targeted mixing of liquids in test tubes. Further applications of medical robots can be found in the fields of diagnostics, care, and out-patients treatment.

Innovations made in recent years have revealed another area with a direct association to conventional medicine that benefits from robotics: rehabilitation and its associated measures. So-called exoskeletons, support structures that are equipped with servo motors, are used to help patients to perform everyday sequences of movements. Gears in the HFUS-2UH® series by Harmonic Drive AG are employed in the robot’s joints to ensure required attributes such as freedom from play, compactness and quiet operation. Only by using high-quality, precisely functioning technology, is it possible to offer patients effective rehabilitation training in a three-dimensional work area. As with the application fields described above, many new application areas for medical robots can be expected in future in the area of patient rehabilitation.