scholarly journals On the Merits of Joint Space and Orientation Representations in Learning the Forward Kinematics in SE(3)

2019 ◽  
Author(s):  
Reinhard M. Grassmann ◽  
Jessica Burgner-Kahrs
Keyword(s):  
Joint Space ◽  
Forward Kinematics

Performing Nonsingular Transitions Between Assembly Modes in Analytic Parallel Manipulators by Enclosing Quadruple Solutions

2015 ◽  
Vol 137 (12) ◽  
Author(s):  
Adrián Peidró ◽  
José María Marín ◽  
Arturo Gil ◽  
Óscar Reinoso
Keyword(s):  
Degrees Of Freedom ◽  
Parallel Manipulators ◽  
Joint Space ◽  
Parallel Robots ◽  
Forward Kinematics ◽  
Characteristic Polynomials ◽  
Forward Kinematic ◽  
Three Degrees Of Freedom

This paper analyzes the multiplicity of the solutions to forward kinematics of two classes of analytic robots: 2RPR-PR robots with a passive leg and 3-RPR robots with nonsimilar flat platform and base. Since their characteristic polynomials cannot have more than two valid roots, one may think that triple solutions, and hence nonsingular transitions between different assembly modes, are impossible for them. However, the authors show that the forward kinematic problems of these robots always admit quadruple solutions and obtain analytically the loci of points of the joint space where these solutions occur. Then, it is shown that performing trajectories in the joint space that enclose these points can produce nonsingular transitions, demonstrating that it is possible to design simple analytic parallel robots with two and three degrees-of-freedom (DOF) and the ability to execute these transitions.

scholarly journals Forward Kinematics of Delta Manipulator by Novel Hybrid Neural Network

2021 ◽  
Vol 6 (6) ◽  
pp. 1694-1708
Author(s):  
Mahesh A. Makwana ◽  
Haresh P. Patolia
Keyword(s):  
Neural Network ◽  
Parallel Manipulator ◽  
Robot Manipulator ◽  
Joint Space ◽  
Forward Kinematics ◽  
Data Set ◽  
Hybrid Neural Network ◽  
Parallel Configuration ◽  
Artificial Neural Network Ann ◽  
Positional Data

For the parallel configuration of the robot manipulator, the solution of Forward Kinematics (FK) is tough as compared to Inverse Kinematics (IK). This work presents a novel hybrid method of optimizing an Artificial Neural Network (ANN) specifically Multilayer Perceptron (MLP) with Genetic Algorithm (GA) and Step-wise Linear Regression (SWLR) to solve the complex FK of Delta Parallel Manipulator (DPM). The joint space angular positional data has been iterated using IK to generate point cloud of Cartesian space positional data. This data set is highly random and broad which leads to higher-order nonlinearity. Hence, normalization of the dataset has been done to avoid outliers from the dataset and to achieve better performance. The developed ANN based MLP gave a mean square error of 0.0000762 and an overall R2 value of 0.99918. Finally, the proposed network has been simulated to solve FK of the parallel manipulator and to check its efficacy. For given joint angles, the proposed network predicted positional values which are in good approximation with known trajectory solved by standard analytical method.

scholarly journals DESAIN DAN PEMODELAN HUMANOID ROBOT

ROTASI ◽  
2014 ◽  
Vol 16 (2) ◽  
pp. 6
Author(s):  
Munadi Munadi ◽  
Beni Anggoro
Keyword(s):  
Humanoid Robot ◽  
Joint Space ◽  
Forward Kinematics

Artikel ini memaparkan tahapan dalam mendesain kontruksi mekanik humanoid robot yang sederhana. Desain sebagai tahapan awal dalam pembuatan humanoid robot sebelum dilakukan pemodelan kinematik dan pemodelan dinamik. Untuk pemodelan kinematik akan dilakukan analisa  forward kinematics dengan menggunakan notasi parameter Denavit-Hartenberg (DH parameter). DH parameter menggunakan matrik homogeneous transformation 4x4 untuk menyatakan hubungan spasial antara dua link yang berhubungan, sehingga dengan matrik transformasi tiap link humanoid robot yang diperoleh dapat menyederhanakan masalah forward kinemtic. Pada pemodelan dinamik akan dilakukan analisa torsi pada joint ankle dengan menggunakan persamaan Lagrangian. Pemodelan dinamik diperoleh energi kinetik dan energi potensial yang terdapat pada tiap link humanoid robot, sehingga dari turunan persamaan Lagrangian diperoleh torsi pada joint ankle humanoid robot. Dalam pergerakan humanoid robot pada joint space mempunyai jalur lintasan (trajectory) sebagai fungsi trajectory terhadap waktu. Proses desain menggunakan alat bantu software SolidWorks dan untuk analisa perhitungan kinematik dan dinamik menggunakan software MATLAB.

scholarly journals Degeneracy Study of the Forward Kinematics of Planar 3-RP̱R Parallel Manipulators

2006 ◽  
Vol 129 (12) ◽  
pp. 1265-1268 ◽  
Author(s):  
P. Wenger ◽  
D. Chablat ◽  
M. Zein
Keyword(s):  
Characteristic Polynomial ◽  
Parallel Manipulators ◽  
Joint Space ◽  
Industrial Applications ◽  
Forward Kinematics ◽  
Double Root ◽  
Degree Polynomial ◽  
New Family ◽  
Planar Manipulators ◽  
First Time

This paper investigates two situations in which the forward kinematics of planar 3-RP̱R parallel manipulators degenerates. These situations have not been addressed before. The first degeneracy arises when the three input joint variables ρ1, ρ2, and ρ3 satisfy a certain relationship. This degeneracy yields a double root of the characteristic polynomial in t=tan(φ∕2), which could be erroneously interpreted as two coalesce assembly modes. However, unlike what arises in nondegenerate cases, this double root yields two sets of solutions for the position coordinates (x,y) of the platform. In the second situation, we show that the forward kinematics degenerates over the whole joint space if the base and platform triangles are congruent and the platform triangle is rotated by 180deg about one of its sides. For these “degenerate” manipulators, which are defined here for the first time, the forward kinematics is reduced to the solution of a third-degree polynomial and a quadratic in sequence. Such manipulators constitute, in turn, a new family of analytic planar manipulators that would be more suitable for industrial applications.

Long-Term Outcomes after Colton Type I and II Fractures of the Olecranon

2019 ◽  
Vol 13 (1) ◽  
pp. 208-216
Author(s):  
Thord von Schewelov ◽  
Fredrik Hertervig ◽  
Per-Olof Josefsson ◽  
Jack Besjakov ◽  
Ralph Hasserius
Keyword(s):  
Joint Space ◽  
Type I ◽  
Type Ii ◽  
Men And Women ◽  
Radiographic Outcomes ◽  
Fracture Event ◽  
Comminuted Fractures ◽  
Fracture Types ◽  
Transverse Fractures ◽  
Olecranon Fractures

Background: It is unclear if the outcomes differ in different subtypes of olecranon fractures. Objective: Evaluate the outcomes of different Colton types of olecranon fractures, and if outcomes differ in dominant and non-dominant arms and in men and women. Methods: We evaluated primary journals and radiographs in 40 men and 55 women with isolated olecranon fractures and classified fractures according to Colton. Mean 19 years after fracture event, we re-examined subjective, clinical and radiographic outcomes in the former patients, using the uninjured arms as controls. Results: 89% of patients with Colton type I fractures reported at follow-up no subjective differences between the elbows, 84% with type II oblique/transverse fractures and 84% with type II comminuted fractures (p=0.91). The uninjured to former fractured arm differences in elbow range of motion and strength were no different in the 3 fracture types, the proportions of individuals with radiographic elbow degenerative changes were greater in type II than in type I factures (p<0.001), and there were no differences between the proportions of individuals with reduced joint space in the 3 groups (p=0.40). The outcomes were no different if the fractures had occurred in the dominant or non-dominant arms (p=0.43), or in men or women (p=0.43). Conclusion: There were no different outcomes after Colton type I, type II oblique/transverse or type II comminuted fractures, no different outcomes between fractures in dominant or non-dominant arms and no different outcomes in men and women.

scholarly journals Type Synthesis of 1T2R Parallel Mechanisms Using Structure Coupling-Reducing Method

2019 ◽  
Vol 32 (1) ◽  
Author(s):  
Haitao Liu ◽  
Ke Xu ◽  
Huiping Shen ◽  
Xianlei Shan ◽  
Tingli Yang
Keyword(s):  
Explicit Form ◽  
Parallel Mechanism ◽  
Analytic Solutions ◽  
Forward Kinematics ◽  
Parallel Mechanisms ◽  
Type Synthesis ◽  
Real Time Control ◽  
Time Control ◽  
Topological Characteristics ◽  
Zero Coupling

Abstract Direct kinematics with analytic solutions is critical to the real-time control of parallel mechanisms. Therefore, the type synthesis of a mechanism having explicit form of forward kinematics has become a topic of interest. Based on this purpose, this paper deals with the type synthesis of 1T2R parallel mechanisms by investigating the topological structure coupling-reducing of the 3UPS&UP parallel mechanism. With the aid of the theory of mechanism topology, the analysis of the topological characteristics of the 3UPS&UP parallel mechanism is presented, which shows that there are highly coupled motions and constraints amongst the limbs of the mechanism. Three methods for structure coupling-reducing of the 3UPS&UP parallel mechanism are proposed, resulting in eight new types of 1T2R parallel mechanisms with one or zero coupling degree. One obtained parallel mechanism is taken as an example to demonstrate that a mechanism with zero coupling degree has an explicit form for forward kinematics. The process of type synthesis is in the order of permutation and combination; therefore, there are no omissions. This method is also applicable to other configurations, and novel topological structures having simple forward kinematics can be obtained from an original mechanism via this method.

scholarly journals FRI0499 ACROMEGALY ARTROPATHY: IS THERE SOMETHING MORE BEHIND THE PAIN? A CROSS-SECTIONAL STUDY TO EVALUATE RHEUMATIC DISEASE IN GROWTH HORMONE SECRETING TUMOR PATIENTS

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 848.1-848
Author(s):  
M. Scarati ◽  
S. Parisi ◽  
N. Prencipe ◽  
M. C. Ditto ◽  
E. Ghigo ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Logistic Regression ◽  
Rheumatic Disease ◽  
Power Doppler ◽  
Connective Tissue Diseases ◽  
Joint Damage ◽  
Joint Space ◽  
Tumor Patients ◽  
Cross Sectional ◽  
Significant Difference

Background:Acromegaly is a rare disease with a remarkable impact on patients, both in terms of life expectancy and quality of life. Osteo-articular complications are one of the most frequently reported bothers. The “acromegaly artropathy” characterizes more than 70% of patients at diagnosis. Artropathy affects both spine and peripheral joints. A recent prospective study documented progression of acromegalic arthropathy identified as a worsening of osteophytes and joint space narrowing in 72–74% of patients despite long-term biochemical control. In addiction the Literature has occasionally reported cases of simultaneous presence of rheumatic diseases (rheumatoid arthritis, polymyalgia rheumatica, undifferentiated connective tissue diseases) and acromegaly and in all these cases the treatment has been delayed, because of wrong symptoms attribution to acromegaly artropathy.Objectives:The primary goal of the study is to better characterize joint pain in acromegaly patients and to evaluate the prevalence of rheumatic disease in growth hormone (GH) secreting pituitary tumor patients.Methods:We enrolled 20 acromegaly subjects (AS) and 20 control subjects (CS). In each subject immunological pattern (rheumatoid factor – RF; antinuclear antibodies - ANA, ENA; anti-citrullinated protein antibodies - ACPA; erythrocyte sedimentation rate – ESR) has been evaluated; they, also, underwent bilateral joint ultrasound of hands and wrists and nail capillaroscopy. The Chi square test and the Fisher’s exact test were used to evaluate the association between binary variables, while the Spearman’s test to evaluate the correlation of continuous ones. A multiple or logistic regression model was calculated in order to define the association between the capillaroscopic alterations and other detected variables.Results:Articular pain emerged as significantly more frequent in AS (p = 0.0269). No statistically significant differences are detected regarding immunological pattern. ANA and ENA screening resulted positive in 10% in AS and in 5% in CS. No IgA ACPA were detected in AS or CS, while IgG ACPA were positive only in one AS subject. No significant differences were detected between IgM and IgG RFin the two groups (AS 5% and CS 0%). Three fold higher IgG FR in AS compared to CS were detected. ESR levels were significantly higher than CS (p = 0.0405), as well as increased power doppler (PWD) articular uptake (AS 30% vs CS 5% p 0.081). The capillaroscopic evaluation showed a significant difference in almost each parameter that has been evaluated (logistic regression: number of enlargement p 0.004, hemorragies p 0.01 and capillaries p 0.001), showing a moderate-severe microangiopathy in AS. Interestingly, analyzing only the acromegaly cohort, we noticed higher GH levels at the enrollment in patients which developed capillary enlargements (GH: 0.95 ng/ml IQ 0,6-1,6) compared to other ones (GH: 0.55 ng/ml IQ 0.4-0.7; p = 0.08) and a significant lower number of hemorrhages (p = 0.02) in patients treated with GH antagonist pegvisomant.Conclusion:Our results demonstrated that joint damage in acromegaly does not seem to have an autoimmune etiology. Therefore, articular damage is mechanical and increased ESR and PWD alterations seems to confirm the presence of an inflammatory component. In addition, acromegaly is characterized by a microvascular pattern of moderate-severe microangiopathy, without correlation to IGF-I, but GH levels. Although requiring further confirmatory studies, our preliminary results seem to indicate how the capillaroscopic examination could be useful to detect earlier microangiopathy and to identify patients with a greater risk of macroangiopathy development..References:[1]Claessen KMJA et al. Bone and joint disorders in acromegaly. Neuroendocrinology. 2016;103(1):86-95.[2]Örük G et al. Is every joint symptom related to acromegaly? Endocrine. 2013 Apr;43(2):404-11.Disclosure of Interests:None declared

scholarly journals Camptodactyly-Arthropathy-Coxa Vara-Pericarditis Syndrome Resembling Juvenile Idiopathic Arthritis: A Single-Center Experience from Southern Turkey

2021 ◽  
pp. 1-6
Author(s):  
Rabia Miray Kisla Ekinci ◽  
Sibel Balci ◽  
Haldun Dogan ◽  
Serdar Ceylaner ◽  
Celal Varan ◽  
...  
Keyword(s):  
Juvenile Idiopathic Arthritis ◽  
Pericardial Effusion ◽  
Early Onset ◽  
Joint Space ◽  
Coxa Vara ◽  
Single Center ◽  
The Third ◽  
Single Center Experience ◽  
Southern Turkey

Camptodactyly-arthropathy-coxa vara-pericarditis (CACP) syndrome, caused by biallelic pathogenic mutations in the <i>PRG4</i> gene, is characterized by early-onset camptodactyly, noninflammatory arthropathy, coxa vara deformity, and rarely, pericardial effusion. Herein, we report 3 patients with CACP syndrome from 2 unrelated families. All patients are female, born to consanguineous parents, and had camptodactyly since the first years of their lives. Two patients had a prior diagnosis of juvenile idiopathic arthritis. Hip changes were present in 2 patients, and 2 of 3 patients had undergone surgery for camptodactyly. Routine echocardiographic evaluations were normal during the 2-year follow-up. This paper represents the third study including CACP patients from Turkey. Clinically, all 3 patients resembled juvenile idiopathic arthritis cases and received unnecessary medication. There is also an ongoing need for improving awareness of CACP and an effective treatment focusing on the lubrication of the joint space in CACP patients.

Meniscal Deficiency Period and High Body Mass Index Are Preoperative Risk Factors for Joint Space Narrowing After Meniscal Allograft Transplantation

2021 ◽  
Vol 49 (3) ◽  
pp. 693-699
Author(s):  
Sang-Min Lee ◽  
Seong-Il Bin ◽  
Jong-Min Kim ◽  
Bum-Sik Lee ◽  
Kuen Tak Suh ◽  
...  
Keyword(s):  
Risk Factors ◽  
Femoral Condyle ◽  
Joint Space ◽  
Preoperative Risk ◽  
Meniscal Allograft Transplantation ◽  
Time Points ◽  
Allograft Transplantation ◽  
Preoperative Risk Factors ◽  
Meniscal Allograft ◽  
The Difference

Background: Several studies have reported further reduction in joint space width (JSW) after meniscal allograft transplantation; some contributing postoperative factors are known, although preoperative factors remain unclear. This study is the first to analyze the preoperative risk factors for reduced JSW in patients after lateral meniscal allograft transplantation (LMAT). Hypothesis: Poor cartilage status and high preoperative body mass index (BMI) influence the postoperative progression of joint space narrowing. Study Design: Case-control study; Level of evidence, 3. Methods: We retrospectively studied 79 patients after LMAT who were observed for at least 5 years. JSWs on weightbearing flexion posteroanterior radiographs were measured preoperatively and at the 5-year mark. Differences in JSW were divided into more progression and less progression groups. The modified Outerbridge cartilage grades based on magnetic resonance imaging assessments were compared at subtotal/total meniscectomy and at LMAT to determine the difference between time points. Preoperative between-group differences in sex, age, surgical side, follow-up period, weight, height, BMI, and meniscal deficiency period were analyzed. Clinical outcomes were evaluated using the Lysholm score. Data were examined using univariate and multivariate logistic regressions. Results: Radiographically, the overall change in JSW from preoperative to follow-up was 0.58 mm (range, –0.23 to 1.83 mm). Reductions in JSW in the more progression and less progression groups were 0.94 ± 0.32 and 0.22 ± 0.21 mm (mean ± SD), respectively. There was no difference in cartilage status between the groups at meniscectomy or LMAT; however, changes between time points were significant on the lateral femoral condyle and lateral tibial plateau. Clinically, there were significant differences in weight, BMI, and meniscal deficiency period between the 2 groups. Postoperative Lysholm scores increased as compared with the preoperative scores, but there was no difference among the postoperative time points. In the univariate logistic regression risk analysis, weight, BMI, meniscal deficiency period, and the difference in cartilage status between time points for the lateral femoral condyle and lateral tibial plateau were identified as significant. In the subsequent multivariate logistic regression, BMI (odds ratio, 1.45; P = .016) and meniscal deficiency period (odds ratio, 1.21; P = .037) were the statistically significant factors. Conclusion: BMI and meniscal deficiency period were preoperative risk factors for JSW narrowing after LMAT. This suggests that the meniscal deficiency period from meniscectomy to LMAT may be shortened and that proper weight management can lead to successful LMAT.

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