Joint Position Research Articles

Relationship Between the Flexion Torque of the First Metatarsophalangeal Joint and Intrinsic Foot Muscles Depends on the Ankle Joint Position.

Clinicians and researchers are beginning to pay attention to the importance of the intrinsic foot muscles (IFMs). Among IFMs, the abductor hallucis (AbH) is associated with foot disorders. However, so far no method for assessing the strength of the AbH has been established. In addition, previous studies have shown increased IFM activity in the plantarflexed position of the ankle. Therefore, this study tests the hypothesis that a correlation will be found between the cross-sectional area (CSA) of the AbH and the flexion torque and that the first metatarsophalangeal (MTP) joint would be stronger in the plantarflexed (PF) position of the ankle joint than in the neutral (N) position. Eight male and 8 female patients (16 lower limbs) were included in this study to measure the CSA of IFM and the extrinsic foot muscles of the lower leg. Furthermore, the flexion torque of the first MTP joint was measured using a handheld dynamometer at the N and PF positions of the ankle joint. Correlation analysis was performed to examine the relationship between the CSA of each muscle and the flexion torque of the first MTP joint in the N and PF positions. In the N position, a correlation was found between the flexion torque of the first MTP joint and the CSA of the AbH (r = 0.818), flexor hallucis brevis (r = 0.730), and flexor hallucis longus (r = 0.726). In the PF position, a correlation was found between the flexion torque of the first MTP joint and the CSA of the AbH (r = 0.863) and flexor hallucis brevis (r = 0.680). (P < .05). Overall, this study suggested that by measuring flexion torque of the first MTP joint in the PF position, AbH strength can be estimated without using any expensive equipment. Level V, mechanism-baced reasoning.

Emergency Department Care for Prepubescent Patients Who Have Been Sexually Abused: Joint Position Statement.

Emergency Department Care for Prepubescent Patients Who Have Been Sexually Abused: Joint Position Statement.

Impact of Glycemic Control on Shoulder Proprioception in Type 2 Diabetes Mellitus: Mediating the Connection - Insights from a Cross-Sectional Analysis.

Shoulder proprioception is vital and this cross-sectional study investigated the association between glycemic control and shoulder joint proprioception in Type 2 Diabetes Mellitus (T2DM). A total of 120 participants, including 60 with T2DM and 60 healthy individuals, were assessed for shoulder joint position sense (JPS) using a digital inclinometer. The T2DM group exhibited significantly greater mean shoulder joint position errors in flexion (4.32° vs 2.15°), abduction, medial rotation, and lateral rotation compared to the healthy group (p < 0.001). The study found significantly greater shoulder joint position errors in the T2DM group compared to the healthy group, highlighting notable proprioceptive deficits in individuals with T2DM. Additionally, a significant positive correlation was found between HbA1c levels and shoulder joint position errors in the T2DM group, suggesting a link between long-term glycemic control and proprioceptive accuracy. The significant positive correlation between HbA1c levels and shoulder joint position errors suggests that poor glycemic control is associated with impaired proprioception in T2DM patients. This underscores the need for comprehensive management strategies to mitigate proprioceptive deficits and improve the quality of life in individuals with T2DM.

Fertility Preservation in Individuals With Cancer: A Joint Position Statement From APHON, CANO/ACIO, and ONS.

Fertility Preservation in Individuals With Cancer: A Joint Position Statement From APHON, CANO/ACIO, and ONS.

Factors that influence the angular error in active knee angle reproduction tests: A systematic review and meta-analysis.

The systematic review and meta-analysis investigated subject-independent test factors that influence the absolute angle error in active knee angle reproduction tests. Five electronic databases were searched to identify relevant studies published before 20 December 2023. Studies were included that were published in either English or German and that investigated joint proprioception in the healthy knee. Included studies were also required to have participants 18-60 years old and free of lower-limb injury, neurological disorders and diseases affecting joint position sense. Risk of bias was assessed using a Cochrane risk-of-bias tool. Of the 2023 articles identified, 26 studies (1082 participants) were included in the meta-analysis. The meta-analysis showed a significant pooled standard mean difference in the absolute angular error for body orientation, direction of movement and fatigue. Active knee angle reproduction tests were found to have a lower absolute angular error when performed in the sitting position compared to the prone position (SMD = -0.56; 95% CI = -1.00 to -0.12). The absolute angular error was found to be greater in cases of knee flexion compared to knee extension (SMD = 0.71; 95% CI = 0.18-1.24). General and local muscle fatigue were found to result in a higher absolute angular error (SMD = 1.39; 95% CI = 1.04-1.75). Hence, fatigue, body orientation and direction of movement influence the extent of the absolute angular error in active knee angle reproduction tests. Practitioners should be aware that the test conditions and the patient's level of fatigue can affect the results of such tests and that directly comparing results obtained using different test protocols may not be appropriate. The test protocol should be well documented and applied consistently in the clinical setting. Level III, systematic review with meta-analysis.

Towards needed improvements in inherited metabolic medicine in adulthood: The SIMMESN adult metabolic working group and MetabERN Joint Position Statement

Inherited metabolic disorders (IMDs), previously considered as a paediatric sub-specialisation are more and more prevalent in adults, thanks to improved survival, and the expansion of diagnostic tools detecting attenuated–late onset forms in adulthood. Italy is one of the countries with the highest number of IMDs screened by dry blood spots in neonates, allowing them to receive early treatments and to reach adult age. Despite this, awareness of IMDs is still low by the adult medical community, with difficulties in transition and transfer of patients to adult services and unmet patient needs. In 2022, a collaboration between the adult metabolic working group of the Italian Society for the Study of Inherited Metabolic Disorders and Neonatal Screening (SIMMESN) and the European Reference Network for Hereditary Metabolic Disorders (MetabERN) was established to face problems linked to IMDs in adulthood. “The Statement of Udine” was developed to guide further steps towards improvements in inherited metabolic medicine in adults, referencing the experience from the UK. The aim of this paper is to present “The Statement of Udine” explaining its background and its possible applications.

No difference in laxity, proprioception and neuromuscular control after suture-tape augmented ACL repair of acute proximal avulsions versus ACL reconstruction using hamstring autografts in young, active population.

The purpose of this study is to compare results of suture-tape augmented anterior cruciate ligament (ACL) repair (internal bracing [IB]) and ACL reconstruction (ACLR) with hamstring autograft in terms of laxity, proprioception and neuromuscular control. The hypothesis was that with strict indications IB may provide better results in proprioception and neuromuscular control. Patients with unilateral ACL injury treated with IB or ACLR with hamstring autograft were enroled in this retrospective study. Anterior tibial translation (ATT) in 30° and 90° of flexion was measured with Rolimeter. The joint position sense (JPS) test was performed in 30° and 60° of flexion using Biodex System 4Pro. The time-synchronized motion capture system and surface electromyography set were used during dynamic tasks to assess knee valgus and semitendinosus (ST) and biceps femoris (BF) activities. Comparisons between both techniques and operated versus contralateral healthy knees were performed. The study groups involved 28 patients after ACLR (21.8 ± 4.8 years) and 20 patients after IB (25.8 ± 10.5 years) with the average follow-up 30 ± 18 and 28 ± 15 months, respectively. The ATT did not differ significantly between operated groups. In 30° of flexion ATT for ACLR was significantly higher in operated than in contralateral knee (5.8 ± 2.4 mm vs. 4.3 ± 1.3 mm, p < 0.001). The JPS test and dynamic knee valgus presented no significant differences. The ACLR group presented significantly higher ST (p = 0.048) and BF (p = 0.012) activity comparing operated to contralateral knee in dynamic tasks. Suture-tape augmented ACL repair and ACLR with hamstring autograft yield similar results in terms of laxity, proprioception and neuromuscular control. Level III: Retrospective comparative study.

Investigating Feed-Forward Back-Propagation Neural Network with Different Hyperparameters for Inverse Kinematics of a 2-DoF Robotic Manipulator: A Comparative Study

Inverse kinematics is a significant challenge in robotic manipulators, and finding practical solutions plays a crucial role in achieving precise control. This paper presents a study on solving inverse kinematics problems using the Feed-Forward Back-Propagation Neural Network (FFBP-NN) and examines its performance with different hyperparameters. By utilizing the FFBP-NN, our primary objective is to ascertain the joint angles required to attain precise Cartesian coordinates for the end-effector of the manipulator. To accomplish this, we first formed three input-output datasets (a fixed-step-size dataset, a random-step-size dataset, and a sinusoidal-signal-based dataset) of joint positions and their respective Cartesian coordinates using direct geometrical formulations of a two-degree-of-freedom (2-DoF) manipulator. Thereafter, we train the FFBP-NN with the generated datasets using the MATLAB Neural Network Toolbox and investigate its potential by altering the hyperparameters (e.g., number of hidden neurons, number of hidden layers, and training optimizer). Three different training optimizers are considered, namely the Levenberg-Marquardt (LM) algorithm, the Bayesian Regularization (BR) algorithm, and the Scaled Conjugate Gradient (SCG) algorithm. The Mean Squared Error is used as the main performance metric to evaluate the training accuracy of the FFBP-NN. The comparative outcomes offer valuable insights into the capabilities of various network architectures in addressing inverse kinematics challenges. Therefore, this study explores the application of the FFBP-NNs in tackling the inverse kinematics, and facilitating the choice of the most appropriate network design by achieving a portfolio of various experimental results by considering and varying different hyperparameters of the FFBP-NN.

Effects of Muscular Fatigue on Position Sense in Two Phases of the Menstrual Cycle.

It is generally accepted that local muscular fatigue can negatively affect position sense. Interestingly, it has been proposed that in women, position sense and neuromuscular coordination may be affected by fluctuations of estrogen and progesterone levels. The aim of this study was to examine the possible effect of localized muscle fatigue on knee joint position sense at two phases of the menses: follicular and luteal. Twenty physically active females aged 19-30 years, with normal menses, volunteered for this study. An isokinetic dynamometer was used to evaluate proprioception and perform the fatigue protocol of the knee extensors and flexors. Knee proprioception at rest and after fatigue at three knee target angles (30°, 45°, 60°) was measured. A three-way ANOVA analysis with repeated measures was performed. The results showed that the main effect of fatigue was significant, but no main effect of the menstrual cycle phase was found. Additionally, a main effect was found for the target angle (more flexed target knee joint angles were associated with larger angular error deviations). In conclusion, localized muscle fatigue can significantly reduce the accuracy of active knee joint repositioning in both the luteal and the follicular menstrual phases in young, physically active healthy women.

Acute Effect of Post-activation Potentiation on Semi-dynamic Balance in Girl Gymnasts Aged 9–12

Background: Post-activation potentiation (PAP) is a novel warm-up method shown to improve sports performance. This study aimed to investigate the acute impact of this method on semi-dynamic balance while walking on the balance beam among female gymnasts aged 9–12 in Kerman city. Methods: Twenty healthy gymnasts volunteered to participate (height: 138.1±5.04 cm; mass: 40.7±3.12 kg) and were randomly divided into two equal sub-groups. The two groups attended the laboratory on two separate days, 48 hours apart. On the first day, the first sub-group performed a general warm-up (GWU), while the second sub-group performed a PAP warm-up. On the second day, the first sub-group switched to a PAP warm-up, and the second sub-group switched to a GWU. After the warm-up, the subjects took a two-minute rest, and then they walked on the balance beam while their movements were recorded using six motion analyzer cameras that captured the kinematic data of the shoulder, thigh, knee, and ankle joints. The data were processed using a low-pass Butterworth filter and analyzed using one-way ANOVA and paired t tests. Results: The results showed significant differences in shoulder, hip, knee, and ankle joint positions in proximal-distal movements following GWU and PAP warm-ups (P≤0.001). In addition, PAP caused a significant decrease in shoulder, hip, knee, and ankle joint positions in medial-lateral movements compared to GWU (P≤0.001, P≤0.001, P≤0.038, P≤0.001, respectively). Conclusion: PAP warm-up positively affects semi-dynamic balance factors in gymnasts. Given the importance of balance in gymnastics, PAP warm-up is recommended to improve sports performance.

Upper cervical spine syndrome: A new perspective

Headaches are widespread in Western Society; they affect approximately 50% of the adult population in the United States. Headaches can present with a variety of clinical and regional symptoms. Although a headache disorder classification system exists, clinical experience has identified various overlapping causes for headaches. It remains clinically challenging to identify the exact etiology causing headaches. For example, the underlying mechanism of cervicogenic headaches remains elusive, but the upper cervical spine plays a key role. Abnormal upper cervical movement patterns, in combination with muscular dysfunctions, are a possible contributing factor to headaches. The upper vertebral spinal nerves C0-C3 have been correlated with cervicogenic headaches. It has been established that biomechanical dysfunction of the upper cervical spine can contribute to neck pain. The atlas plays a key role in the biomechanical dysfunction in the upper cervical spine. Previously, it has been identified that the relative position of the atlas to the axis correlates with headaches. Additionally, it has been demonstrated that an extended contraction of the homolateral obliquus capitis inferior muscles can result in positional default rotation of the atlas. As managing headaches remains multimodal and challenging, there is enough evidence to support the inclusion of the upper cervical spine to normalize joint position, joint mobility, muscle tonicity, and upright positioning. When recognizing the “upper cervical syndrome” and addressing the functioning of the atlas, clinical outcomes will improve for those treating patients with headaches.

Effects of differences in femoral anteversion and hip flexion angle on hip abductor muscles activity during clam exercise in females.

This study aimed to determine differences in the hip abductor muscle activity during clam exercise at different hip flexion and femoral anteversion angles. Thirty healthy females were divided into two groups based on the femoral anteversion angle: the excessive femoral anteversion group and the normal group. Clam exercise was performed at three different hip flexion angles (60°, 45°, and 30°). Tensor fascia latae, gluteus medius, and superior portion of gluteus maximus activities were measured during the exercise, and the results were normalized to the activity during maximum voluntary isometric contraction to calculate the gluteal-to-tensor fascia latae muscle activation index. The superior portion of gluteus maximus activities at a hip flexion of 60° and 45° were greater than that at 30°. The excessive femoral anteversion group had a lower gluteal-to-tensor fascia latae muscle activation index than the normal group; the gluteal-to-tensor fascia latae muscle activation index for hip flexion at 60° was higher than that at 45°, and the gluteal-to-tensor fascia latae muscle activation index for hip flexion at 60° and 45° were higher than that at 30°. Therefore, the femoral anteversion angle and hip joint position were related to the activity of the hip abductor muscles during clam exercise. These findings may provide a rationale for instructing exercises to maximize the activity of the hip abductor muscles in individuals with an excessive femoral anteversion angle.

Wearable Robot Design Optimization Using Closed-Form Human-Robot Dynamic Interaction Model.

Wearable robots are emerging as a viable and effective solution for assisting and enabling people who suffer from balance and mobility disorders. Virtual prototyping is a powerful tool to design robots, preventing the costly iterative physical prototyping and testing. Design of wearable robots through modelling, however, often involves computationally expensive and error-prone multi-body simulations wrapped in an optimization framework to simulate human-robot-environment interactions. This paper proposes a framework to make the human-robot link segment system statically determinate, allowing for the closed-form inverse dynamics formulation of the link-segment model to be solved directly in order to simulate human-robot dynamic interactions. The paper also uses a technique developed by the authors to estimate the walking ground reactions from reference kinematic data, avoiding the need to measure them. The proposed framework is (a) computationally efficient and (b) transparent and easy to interpret, and (c) eliminates the need for optimization, detailed musculoskeletal modelling and measuring ground reaction forces for normal walking simulations. It is used to optimise the position of hip and ankle joints and the actuator torque-velocity requirements for a seven segments of a lower-limb wearable robot that is attached to the user at the shoes and pelvis. Gait measurements were carried out on six healthy subjects, and the data were used for design optimization and validation. The new technique promises to offer a significant advance in the way in which wearable robots can be designed.

GAN-BodyPose: Real-time 3D human body pose data key point detection and quality assessment assisted by generative adversarial network

With the rapid advancement of deep learning and computer vision, these technologies are becoming increasingly vital in areas like virtual reality, medical diagnosis, and sports training. Existing methods for real-time 3D human body pose keypoint detection and quality assessment face significant challenges such as insufficient detection accuracy, low computational efficiency, and high data quality requirements. To address these challenges, we propose an innovative solution, GAN-BodyPose. This approach integrates 3D convolutional neural networks, self-attention mechanisms, and generative adversarial networks to deliver efficient and accurate detection and assessment in real time. The GAN-BodyPose framework combines 3D-CNN and self-attention for effective feature extraction and keypoint detection, enhanced further by generative adversarial networks for superior data quality and accuracy. Our extensive evaluations using a large-scale 3D human body pose dataset demonstrated that GAN-BodyPose outperforms traditional methods, showing improvements in processing speed (15% faster), accuracy in terms of Mean Per Joint Position Error (reduced by approximately 2.2%), and an Area Under the Curve (AUC) score increased by approximately 9.5% compared to HR-Net and other datasets. Additionally, it achieves lower Floating-Point Operations (FLOPs) by about 9.3%, indicating more efficient computational performance. These advancements underline the potential of our approach to significantly enhance user experiences in virtual reality, motion capture, and other real-time applications. The successful application of GAN-BodyPose promises greater efficiency and precision in fields ranging from game development to medical diagnostics, and robust support for human-computer interaction and gesture recognition. This research represents a substantial contribution to deep learning applications in robot control, decision-making, and broadens the research foundation in these domains.

The effects of thoracic mobility versus lumbopelvic stabilization exercises on lower extremity flexibility, dynamic balance and proprioception in patients with chronic ankle instability

BACKGROUND: Chronic ankle instability (CAI) presents neuromuscular control and functional performance difficulties. Although ankle-focused rehabilitation is widely practised, the relative effects of exercises targeting thoracic mobility and lumbopelvic stabilization in addressing CAI have not been thoroughly investigated. OBJECTIVE: The study aims to compare the effects of thoracic mobility and lumbopelvic stabilization exercises in patients with CAI. METHODS: The study was designed as a prospective randomized controlled clinical trial. A total of 30 participants (mean age = 31.93 ± 7.31; 21F/9M) who scored 27 points or on the Cumberland ankle instability tool voluntarily were enrolled in the study. The participants were randomly divided into two groups. In addition to the rehabilitation protocols, each participant was given a home exercise program, including ankle-strengthening exercises (3 times a week). The first group trained with thoracic mobility (TM), while the second group did lumbopelvic stabilization (LS) exercises under supervision twice a week for eight weeks. Participants’ pre and post-treatment assessments spanned an 8-week rehabilitation period, during which ankle and hip joint range of motion measurements were obtained using an electronic goniometer. Additionally, dynamic balance was assessed through the Y balance test, while ankle proprioception was evaluated using joint position sense measurements. The flexibility was assessed with an active straight leg raise test. RESULTS: Y balance, CAIT, and active straight leg raise test scores were improved in the eighth week in the thoracic mobility group (p&lt; 0.05), while only active straight leg raise test and CAIT scores were significantly different in the lumbopelvic stabilization group (p&lt; 0.05) according to intra group variables. In comparing the post-treatment scores between the groups, the thoracic mobility group had superior results in the joint position sense test for the right side of the hip and plantarflexion. (hip; TM: 70.71 ± 6.80, LS: 68.76 ± 5.50, plantarflexion; TM: 44.24 ± 7.28, LS: 38.30 ± 5.08). CONCLUSION: The findings suggest that while both interventions are effective in addressing various aspects of ankle instability, the thoracic mobility exercises may offer additional benefits, particularly in enhancing joint position sense, thereby providing valuable insights for the optimization of rehabilitation protocols for individuals with chronic ankle instability.

Effect of Integrated Postural Training in Individuals with Text Neck Syndrome

Background: Text neck syndrome is a repetitive stress injury caused by prolonged use of electronic gadgets, particularly smartphones. With smartphone addiction surpassing internet addiction, it has led to increased musculoskeletal problems. Currently, symptomatic treatment for text neck syndrome includes neck pain, postural changes, and cervical proprioceptive errors. The condition is chronic and progressive, and timely intervention and postural correction are crucial to minimize early consequences in later life. The aim of this study was to investigate the effect of integrated postural training in individuals with text neck syndrome. Methods: This study included 80 participants clinically diagnosed with text neck syndrome who were selected based on inclusion and exclusion criteria. They were further divided into two groups, with Group A receiving a conventional exercise program and Group B receiving integrated postural training 3 times a week for 6 weeks. Pre- and post-assessment scores of visual analog scale (VAS), neck disability index (NDI), range of motion (ROM) of the cervical spine, tragus to wall test (TTW), Vernier Caliper measurements for rounded shoulders and cervical joint position error testing (CPJE Testing) were taken and the results were obtained by statistical analysis of the data. Results: The results of this study showed that there was an extremely significant improvement in neck pain, cervical ROM, forward head posture, and rounded shoulder posture in both the groups with a p-value of &lt;0.0001 except for the CPJE testing, which showed to be significant in the Group B with a p-value &lt;0.0001 as compared to Group A. Conclusion: The study concluded that integrated postural training showed significant improvement and has been beneficial in relieving pain, improving cervical range of motion, posture, and the cervical joint position error in individuals with text neck syndrome.

Shoulder proprioception changesin postmastectomy patients: an observational study.

Breast cancer surgery can cause changes in the anatomical structure of the shoulder and in shoulder mobility, leading to the increased possibility of long-term arm morbidity such as lymphedema. This study aims to evaluate the active shoulder joint position sense (AJPS) with and without lymphedema in postmastectomy patients. A total of 66 women, including 22 patients with lymphedema, 22 patients without lymphedema, and 22 healthy controls, were enrolled in the study. Pain severity was evaluated with the Numeric Pain Scale and edema severity was measured with circumferentially at 10cm intervals. The normal range of motion of the shoulder joint was evaluated with the universal goniometer and the AJPS was assessed by active position repetition testing at 55°, 90°, and 125° shoulder flexion targets using the smartphone application "Clinometer." AJPS at 55°, 90°, and 125° shoulder flexion target angles with and without lymphedema were different in all target angles compared to healthy controls (p < 0.01). There was a difference between the absolute error value of AJPS at 55° flexion (p < 0.05), and no difference at 90° and 125° flexion between the with and without lymphedema groups (p > 0.05). This study shows that the AJPS was negatively affected in with and without lymphedema postmastectomy patients compared to healthy controls. This result emphasizes the importance of adding personalized methods for the restoration of joint position sense in addition to rehabilitation programs generally applied to the patient group.

Effects of Whole-Body Vibration Therapy in Weight-Bearing and Non-Weight Bearing Positions for Upper and Lower Extremities on Balance and Cervical Joint Position Sense in Children With Cerebral Palsy.

Cerebral palsy (CP) is a complex pathological entitythat affects muscular control, coordination, proprioception, fine andgross motor abilities, position, stability, and, in some cases, cognition. This study aimed to compare the effects of whole-body vibration therapy (WBVT) in weight bearing and non-weight bearing positions for the upper and lower extremities on balance and cervical joint position sense in children with spastic CP. A randomized controlled trial was carried out on 60 hemiplegic children with spastic CP aged 5-15 years. Following randomization, all participants were allocated into six equal-sized groups based on the application ofWBVT for upper extremities, lower extremities, or both simultaneously in either weight-bearing or non-weight-bearingpositions. Pediatric balance scale (PBS) and laser tracker system were used to assess functional balance and cervical joint position sense. One-way analysis of variancefor Inter-group analysis showed a statistically significant difference among all groups in PBS and cervical joint position sense (p<0.05). WBVT was found to be beneficial in improving balance and cervical joint position sense in both weight-bearing and non-weight-bearing positions for the upper and lower extremities in children with cerebral palsy. However, the simultaneous application of WBVT in weight-bearing positions for both upper and lower extremities showed the most significant improvements in improving both balance and cervical joint position sense, indicating the most efficacious position of this treatment approach in children with cerebral palsy.

Fire performance enhancement of cold-formed steel walls: experimental and numerical study

Cavity-insulated cold-formed steel (CFS) walls, with gypsum plasterboard (GP) on both sides, are widely used in the construction industry. However, their fire performance is compromised by the faster rise in the temperature of the hot flange (HF), which is influenced by cavity insulation and board joints. This study aims to optimize cavity insulation configuration to enhance fire performance. Two mid-scale, non-load-bearing fire experiments on CFS walls were conducted, employing double-layered GP boards and rock wool insulation, under ISO834 time-temperature fire conditions. Meanwhile, a finite element model of physical space fluid-heat coupling of furnace-CFS walls considering joints with time was developed to reveal joint mechanisms and configurations. The results showed that non-insulated stud CFS walls had slower HF temperature rise and similar insulation compared to insulated counterparts, delaying HF temperature reach to 537 °C by 14 min. The base-layer joints had the least adverse impact on the HF temperature rise than overlapped joints and face-layer joints. The HF temperatures for various joint configurations reached 537 °C at different times: 57 min for the face layer, 62 min for the base layer, and 49 min for overlapped joints. Considering the construction cost-effectiveness, it was found that adding steel strips (the same width as the flange) at the joint position could significantly decelerate the HF temperature rise. In 60 min, the HF temperature in the model with additional steel strips dropped by 94 °C lower than in the 10 mm overlapped joint model. Finally, based on finite element results, design equations were proposed for predicting HF temperature variation over time across joint types.

A unified formulation of geometry-aware discrete dynamic movement primitives

Learning from demonstration (LfD) is considered as an efficient way to transfer skills from humans to robots. Traditionally, LfD has been used to transfer Cartesian and joint positions and forces from human demonstrations. The traditional approach works well for some robotic tasks, but for many tasks of interest, it is necessary to learn skills such as orientation, impedance, and/or manipulability that have specific geometric characteristics. An effective encoding of such skills can be only achieved if the underlying geometric structure of the skill manifold is considered and the constrains arising from this structure are fulfilled during both learning and execution. However, typical learned skill models such as dynamic movement primitives (DMPs) are limited to Euclidean data and fail in correctly embedding quantities with geometric constraints. In this paper, we propose a novel and mathematically principled framework that uses concepts from Riemannian geometry to allow DMPs to properly embed geometric constrains. The resulting DMP formulation can deal with data sampled from any Riemannian manifold including, but not limited to, unit quaternions and symmetric and positive definite matrices. The proposed approach has been extensively evaluated both on simulated data and real robot experiments. The performed evaluation demonstrates that beneficial properties of DMPs, such as convergence to a given goal and the possibility to change the goal during operation, apply also to the proposed formulation.