# Automated and Controlled System for Analysis of Residual Limbs Thermograms of Transtibial Amputees
## 3 Methodology
### Software Implementation
#### Thermographic Images Analysis  
For the automated system we consider the following analysis performed on the thermal images:  
* Average temperature computation of the stump considering each view.
* Calculation of the standard deviation of the stump per view.  
In order to test the designed software and to avoid background useless information, ten thermal captures for each participant with a transtibial amputation are taken using the cabin. An example of one of these photos is shown in Figure 1b, which can be compared with Figure 1b of a thermographic image without the use of the cabin.  
The thermographic camera used during this study was an FLIR C3 thermal camera with WIFI. This camera requires a minimum focus distance of 0.15 m, has a thermal sensitivity of less than 0.10 \({}^{\circ}\)C, and a measurement accuracy of \(+/-2\) \({}^{\circ}\)C or \(+/-2\)% at 25 \({}^{\circ}\)C. It also has a set of parameters that can be tuned for specific tasks, for instance, in this study we set the emissivity value to 0.98, which is the accepted emissivity value for human skin found in literature. In addition, a target distance was set to 0.45 m, which is the distance between the camera and the center of the cabin. Proper camera calibration needs to be performed by an authorized center; however, before the capture of the thermal images, the FLIR C3 temperature range was set from 20 to 40 \({}^{\circ}\)C, aiming to detect the temperature of the stump within this range in such a way that color map variations can be used for a qualitative  
Figure 5: Flow diagram of the GUI functionality. This diagram illustrates the user experience while using the app.  
analysis. This temperature range was fixed by setting an environment temperature of 20 \({}^{\circ}\)C and placing a glass of water at 40 \({}^{\circ}\)C, 45 cm away from the camera. During the image processing stage, no reflected temperature compensation nor measurement errors were eliminated resulting from non-axial measurement of the distance of the camera from the object; however, these will be considered for further improvements in order to achieve a more precise analysis. Changes in ambient temperature, e.g., background objects, were not considered at first. Once they were found to impair processing, the proposal of an automated cabin was suggested to isolate the stump from air movements and background objects with different emissivity values in order to improve processing performance. The selection of participants needs to satisfy the clinical trial protocol approved by an ethics committee (PR2021-01). All participants in this study must have experienced at least one year since their amputation surgery.  
Two sets of five thermal images each are taken for each participant. The first set is captured when the participant arrives at the laboratory (Instance 1), while the second set is captured after a 10 min walk (Instance 2) (Example of this image can be seen in Figure 6). A total of ten thermographic images per thermographic analysis are shot, covering the positions lateral, frontal, medial, inferior, and posterior of the stump.  
To capture the images for the analysis, the mobile platform follows a fixed trajectory. The following subsection describes the control solution to achieve the desired path.