Dynamic Models Identification for Kinematics and Energy Consumption of Rotary-Wing UAVs during Different Flight States.

This article presents the method of identifying dynamic models for different flight states of a rotary-wing UAV for simulations. Experimental flights with real-life UAVs were conducted to obtain data necessary for identification. Dynamic models were identified with time series methods performed using Matlab R2022b software. Such models can later be implemented in simulations to represent the behavior of real-life objects. Simulation is the first stage of developing a real-life UAV system, where prototyping with physical models is problematic. Therefore, obtaining accurate models is crucial for the simulation process to be reliable. Presented methods do not require knowledge of UAV construction, and complex mathematical equations do not need to be derived. Also, verification of obtained models was performed to make sure that they were identified correctly. In particular, the presented method was proven effective and successfully used in some applications.

Effects of Viscosupplementation on Quality of Knee Joint Arthrokinematic Motion Analyzed by Vibroarthrography.

OBJECTIVE: To evaluate the influence of viscosupplementation on osteoarthritic knee arthrokinematics analyzed by VAG. It is considered that intra-articular hyaluronic acid injection may improve the function of synovial joints by recovery of friction-reducing properties of articular environment. DESIGN: Thirty-five patients with knee osteoarthritis (grade II according to the Kellgren-Lawrence system) and 50 asymptomatic subjects were enrolled in the study. Patients were analyzed at 3 time points: 1 day before and 2 weeks and 4 weeks after single injection of 1.5% cross-linked hyaluronate. Control subjects were tested once. The vibroarthrographic signals were collected during knee flexion/extension motion using an accelerator and described by variation of mean square (VMS), mean range (R5), and power spectral density for frequency of 50 to 250 Hz (P1), and 250 to 450 Hz (P2). RESULTS: Patients before viscosupplementation were characterized by about 2-fold higher values of vibroarthrographic parameters than controls. Two weeks after the procedure, the values of R5, P1, and P2 significantly decreased, in comparison to pre-injection. At 4 weeks post-injection, we noted a significant increase in R5, P1, and P2 values, when compared to 2 weeks post-injection. Finally, at 4 weeks post-injection, the level of VMS, R5, and P2 parameters did not differ from values obtained at pre-injection. CONCLUSIONS: We showed that viscosupplementation may be effective in providing arthrokinematics improvement, but with a relatively short period of duration. This phenomenon is observed as decreased vibroacoustic emission, which reflects a more smooth movement in the joint.

Effects of Immobilization and Re-Mobilization on Knee Joint Arthrokinematic Motion Quality.

BACKGROUND: Knee immobilization is a common intervention for patients with traumatic injuries. However, it usually leads to biomechanical/morphological disturbances of articular tissues. These changes may contribute to declining kinetic friction-related quality of arthrokinematics; however, this phenomenon has not been analyzed in vivo and remains unrecognized. Thus, the aim of the present study is to investigate the effect of immobilization and subsequent re-mobilization on the quality of arthrokinematics within the patellofemoral joint, analyzed by vibroarthrography (VAG). METHODS: Thirty-four patients after 6-weeks of knee immobilization and 37 controls were analyzed. The (VAG) signals were collected during knee flexion/extension using an accelerometer. Patients were tested on the first and last day of the 2-week rehabilitation program. RESULTS: Immobilized knees were characterized by significantly higher values of all VAG parameters when compared to controls (p < 0.001) on the first day. After 2 weeks, the participants in the rehabilitation program that had immobilized knees showed significant improvement in all measurements compared to the baseline condition, p < 0.05. However, patients did not return to normal VAG parameters compared to controls. CONCLUSION: Immobilization-related changes within the knee cause impairments of arthrokinematic function reflected in VAG signal patterns. The alterations in joint motion after 6 weeks of immobilization may be partially reversible; however, the 2-week physiotherapy program is not sufficient for full recovery.

Effects of Viscosupplementation on Knee Joint Arthrokinematics - Pilot Study.

BACKGROUND: Osteoarthritis is one of the most common dysfunctions of the musculoskeletal system and viscosup-plementation is becoming an increasingly popular treatment in OA. However, current knowledge regarding biomechanical changes in synovial joints reveals many discrepancies. Therefore, the aim of our study was to evaluate the effect of visco-supplementation on knee joint arthrokinematics as analyzed by vibroarthrography. MATERIAL AND METHODS: Seventeen individuals diagnosed with moderate knee osteoarthritis (VSC) were examined before and after a single injection of hyaluronate. A control group consisted of 30 asymptomatic individuals. During alter-nating extension/flexion of the knee joint, a 6-second vibroarthrographic signal was recorded using an accelerometer. The following parameters were calculated: variance (VMS), amplitude (R4), and spectral power density in the 50-250 Hz (P1) and 250-450 Hz (P2) bands. RESULTS: Statistical analysis showed significant differences (p<0.05) in the values of R4 and P2, which were higher in the VSC group than among the controls. After viscosupplementation, the values of R4, P1 and P2 in the VSC group de-creased to a level not significantly different from that seen among the controls. CONCLUSIONS: 1. After a single intra-articular HA injection, joint motion-related vibrations were reduced, which was recorded as a decreased intensity of vibroacoustic emission. 2. This suggests that the use of viscosupplementation in pa-tients with moderate knee osteoarthritis may improve qualitative aspects of arthrokinematics.

Assessment of Relationships Between Joint Motion Quality and Postural Control in Patients With Chronic Ankle Joint Instability.

Study Design Controlled laboratory study, cross-sectional. Background Lateral ankle sprains are among the most common injuries encountered during athletic participation. Following the initial injury, there is an alarmingly high risk of reinjury and development of chronic ankle instability (CAI), which is dependent on a combination of factors, including sensorimotor deficits and changes in the biomechanical environment of the ankle joint. Objective To evaluate CAI-related disturbances in arthrokinematic motion quality and postural control and the relationships between them. Methods Sixty-three male subjects (31 with CAI and 32 healthy controls) were enrolled in the study. For arthrokinematic motion quality analysis, the vibroarthrographic signals were collected during ankle flexion/extension motion using an acceleration sensor and described by variability (variance of mean squares [VMS]), amplitude (mean of 4 maximal and 4 minimal values [R4]), and frequency (vibroarthrographic signal bands of 50 to 250 Hz [P1] and 250 to 450 Hz [P2]) parameters. Using the Biodex Balance System, single-leg dynamic balance was measured by overall, anteroposterior, and mediolateral stability indices. Results Values of vibroarthrographic parameters (VMS, R4, P1 and P2) were significantly higher in the CAI group than those in the control group (P<.01). Similar results were obtained for all postural control parameters (overall, anteroposterior, and mediolateral stability indices; P<.05). Moreover, correlations between the overall stability index and VMS, and P1 and P2, as well as between the anteroposterior stability index and P1 and P2, were observed in the CAI patient group, but not in controls. Conclusion In patients with CAI, deficits in both quality of ankle arthrokinematic motion and postural control were present. Therefore, physical therapy interventions focused on improving ankle neuromuscular control and arthrokinematic function are necessary in CAI patient care. J Orthop Sports Phys Ther 2017;47(8):570-577. Epub 4 Nov 2016. doi:10.2519/jospt.2017.6836.