Modern medicine widely uses mechatronic modules in systems of various purposes, such as automated systems of diagnostics, scanning, irradiation. Recently, mechatronic modules in robotic surgical complexes are gaining importance. Thus, with the use of integrated sensors in mechatronic modules, executive manipulators of automated systems, positioning accuracy in defined spatial coordinates can be maintained. This data helps the medical staff to diagnose, monitor the patient's condition and make treatment decisions. The main purpose of sensor support in mechatronic systems is to ensure the accuracy and reliability of the system's functioning. Sensors must be sensitive and stable enough to provide measurements with high accuracy and respond to changes in real time. In addition, similar mechatronic modules are combined with sensors to create bionic limb prostheses, to restore human movement functions in various orthopedic diseases.
 At the same time, the trajectory of the movement of the executive bodies of the mechatronic medical system, regardless of its purpose, during spatial transformations of searching for the coordinates of a real object, must be determined taking into account possible deformations.
 Therefore, the accuracy of real-world displacement in space is determined by sensors that measure the parameters of physical objects. Thus, real transformations can be defined by spatial deviations that can be described using an ellipsoidal model. Accuracy, like the strength of the mechatronic module of a robot arm, is a variable value. They depend not only on the number of joints and the mobility of the hinges, but also on the position of the manipulators in space. At one point of coordinates, the module can apply more force than at another. The same is true for positioning accuracy, where the positioning error is greater at some points than at others. Therefore, an important actual problem in the creation of medical robotic systems is to determine the step-by-step movement of such a module in the workspace.
 Therefore, the purpose of this work is to determine the ellipsoidal TONTOR step model of sensors for automated mechatronic systems, as the motion of the executive manipulators and sensors of the system during transformations from imaginary coordinate space to real space determines trajectory errors. Based on the existing opportunities analyzed in the work application of mechatronic modules in automated medical systems, relevant tasks related to maintaining the positioning accuracy of diagnostic manipulators and sensors are defined. The importance of sensory complexes in measuring various biological parameters that determine the patient's condition is noted. And this involves the application of models of spatial movement of the sensor in the working space of automated equipment, in particular, a robotic mechatronic complex.
 In the work, it is proposed to use the TONTOR step model to increase the accuracy of the realization of the movement trajectory of the sensors of the mechatronic automated system. The results of creating an ellipsoidal model of the TONTOR step, which most accurately reflects the features of moving an object in space during transformations of the transition to real space, are given.