# Ergonomics Evaluation Using Motion Capture Technology--Literature Review
## 1 Introduction
Nowadays, there are many existing motion capture systems based on different approaches to transform real motion into a virtual environment or model. Some systems are based on optical capture, where the object is captured by a system of special cameras. The object is fitted with markers (tags) that the cameras can read, so it is not a recording of the human body but of these markers. The cameras observe the scene from different angles and are jointly calibrated through a system that knows the exact position of each camera in space, allowing the exact position of any marker in space and at any time to be determined [39]. These motion capture systems have excellent recording accuracy, as the number of markers is not limited, so really any part of the body can be fitted. Another advantage is the possibility of recording multiple figures in one space. Modern cameras are usually no longer limited by the correct lighting of the space, so they can be used almost anywhere, which guarantees high flexibility. However, these systems are very space-consuming due to the high number of cameras needed to ensure that the markers do not overlap at any moment. If the markers are obscured by the body or another person and at least two cameras are unable to register the marker at any given time, the trajectory is lost. Moreover, there usually cannot be any obstructions in the area for the cameras to see correctly. Furthermore, the more cameras used, the more the recorded data need to be processed later [40]. The above facts suggest that systems based on this optical principle are very expensive and costly. Producers of these MoCap systems are, for example, Motion Analysis or Vicon [41]. Another option is gyroscopic systems, which work on the basis of gyroscopes placed on individual parts of the body. These systems generate data directly and no postprocessing is required. However, adding an additional person is costly, as a new set needs to be invested in. Gyroscopic systems are preferable to use when high accuracy is not required [42]. Other systems include exoskeleton solutions or the use of markerless technology, where the object is recorded directly, e.g., Kinect [43]. A newer trend for motion capture is kinematic motion capture suits. As a rule, they work on the basis of putting special suits or straps on a proband, on which sensors are gradually deployed. The sensors are attached to the special suit by means of clips. The whole system works on the principle of sensing by magnetic sensors and inertial control [44]. Conventional motion capture suits have sensors on 17 different body parts for sensing the head, upper limbs, including hands, back, torso, and lower limbs, including feet. The sensors work wirelessly with the docking station and computer where the motion is transmitted. The sensing process consists of several steps. First, the suit with the human figure needs to be calibrated to align all sensors with the environment. This is followed by the process of capturing the motion and recording the relevant data from each sensor at each moment. In addition to the aforementioned recording, some tools from different vendors allow the evaluation of the recorded data according to a defined methodology for evaluating the proband's positions. In case other methodologies need to be used, the data can be exported and worked with in other tools or applications [45]. Some of the kinematic suit suppliers allow, in addition to the collection of proband position data, the collection of local muscle load data at a given time. Suppliers of these technologies include Neuron, Rokoko, XSens, and TEA Captiv. The disadvantage of these technologies is the problems with the ambient magnetic field of various devices interfering with the signals of these systems. On the other hand, these suits are significantly cheaper than their alternatives, see above, and their acquisition is, therefore, possible for a wider range of users. It is expected that the technology will become even more affordable in the future.