scholarly journals A Consideration on a Dynamic Control Method for Quadruped Walking Robots

1992 ◽  
Vol 4 (6) ◽  
pp. 526-528 ◽  
Author(s):  
Junji Furusho ◽  
◽  
Akihito Sano ◽  
Yosuke Okajima ◽  
Keyword(s):  
Walking Speed ◽  
Control Method ◽  
Dynamic Control ◽  
Knee Joints ◽  
Walking Robots ◽  
Step Width ◽  
Robot System ◽  
Walking Control ◽  
The Mean ◽  
The Stability

There are many kinds of control methods for quadruped walking robots. In this paper, we deal with a walking control method in which the robot system can utilize the gravity effect very skillfully and the energy can thus be saved. Using computer simulation, we studied the walking control by this method from some aspects, such as the mean walking speed, the variation of the walking speed, and the stability. It is shown that the step width and the bending angle of the knee joints at the touchdown are important factors for walking controls.

Dynamic Force-Position Control of the Walking Robots Motion on Slope

2012 ◽  
Vol 186 ◽  
pp. 98-104 ◽  
Author(s):  
Luige Vladareanu ◽  
Daniel Octavian Melinte
Keyword(s):  
Position Control ◽  
Dynamic Control ◽  
Open Architecture ◽  
Walking Robots ◽  
Robot Motion ◽  
Dynamic Force ◽  
Walking Robot ◽  
Kinematic Modeling ◽  
Dynamic Hybrid ◽  
The Stability

Abstract. The paper presents a strategy for the dynamic hybrid force-position control of the walking robot motion on slope using the ZMP method for dynamic control and a stable and robust method. Through dynamic and kinematic modeling of the walking robots motion an open architecture system was developed which contains five control interfaces. The stability problem of quadruped walking robots, through extendible segments which are designed to reduce the difficulty of walking on slope, and also by using them to avoid obstacles that may occur during a stepping cycle are presented. The results obtained have led to an improvement in the response time to disturbances, to tracking the motion trajectory with higher precision in conditions of high stability and to development of new technological capabilities, adapting the robot walking to movement over sloped terrain, with obstacles and bumps.

Screw Dynamic Modeling and Novel Composite Error-Based Second-order Sliding Mode Dynamic Control for a Bilaterally Symmetrical Hybrid Robot

Robotica ◽  
2021 ◽  
pp. 1-17
Author(s):  
Qiuyue Qin ◽  
Guoqin Gao
Keyword(s):  
Control Method ◽  
Screw Theory ◽  
Sliding Mode ◽  
Virtual Work ◽  
Dynamic Control ◽  
Second Order ◽  
Terminal Sliding Mode ◽  
Fast Terminal Sliding Mode ◽  
Simulation And Experiment ◽  
The Stability

SUMMARY In this research, a dynamic model is first established based on screw theory and the principle of virtual work for a bilaterally symmetrical hybrid robot. By combining a novel composite error (NCE) with second-order nonsingular fast terminal sliding mode (SONFTSM) control method, a NCE-based SONFTSM dynamic control method is further presented to guarantee better trajectory tracking performance and synchronization performance simultaneously. The asymptotic convergence of proposed errors and the stability of the proposed control method have been proved theoretically. Finally, the simulation and experiment are implemented to validate the effectiveness of the proposed control method.

Injuries to the Coronoid Process of the Ulna with Involvement of the Lesser Sigmoid Notch

2020 ◽  
Author(s):  
Valentin Rausch ◽  
Sina Neugebauer ◽  
Tim Leschinger ◽  
Lars Müller ◽  
Kilian Wegmann ◽  
...  
Keyword(s):  
Fragment Size ◽  
Coronoid Process ◽  
Annular Ligament ◽  
Concomitant Injuries ◽  
Proximal Ulna ◽  
Sigmoid Notch ◽  
Coronoid Fractures ◽  
The Mean ◽  
The Stability ◽  
Arthritic Changes

Abstract Introduction This study aimed to describe the involvement of the lesser sigmoid notch in fractures to the coronoid process. We hypothesized that injuries to the lateral aspect of the coronoid process regularly involve the annular ligament insertion at the anterior lesser sigmoid notch. Material and Methods Patients treated for a coronoid process fracture at our institution between 06/2011 and 07/2018 were included. We excluded patients < 18 years, patients with arthritic changes or previous operative treatment to the elbow, and patients with concomitant injuries to the proximal ulna. In patients with involvement of the lesser sigmoid notch, the coronoid height and fragment size (anteroposterior, mediolateral, and craniocaudal) were measured. Results Seventy-two patients (mean age: 47 years ± 17.6) could be included in the study. Twenty-one patients (29.2%) had a fracture involving the lateral sigmoid notch. The mean anteroposterior fragment length was 7 ± 1.6 mm. The fragment affected a mean of 43 ± 10.8% of the coronoid height. The mean mediolateral size of the fragment was 10 ± 5.0 mm, and the mean cranio-caudal size was 7 ± 2.7 mm. Conclusion Coronoid fractures regularly include the lesser sigmoid notch. These injuries possibly affect the anterior annular ligament insertion which is important for the stability of the proximal radioulnar joint and varus stability of the elbow.

Instant 99mTc-Labelled Glucoheptonate Kit for Kidney Imaging

1983 ◽  
Vol 22 (05) ◽  
pp. 246-250 ◽  
Author(s):  
M. Al-Hilli ◽  
H. M. A. Karim ◽  
M. H. S. Al-Hissoni ◽  
M. N. Jassim ◽  
N. H. Agha
Keyword(s):  
Sodium Hydroxide Solution ◽  
Normal Subjects ◽  
Organ Distribution ◽  
Stable Complex ◽  
Scintillation Camera ◽  
Ph Adjustment ◽  
The Mean ◽  
The Stability ◽  
Kidney Imaging ◽  
Mean Concentration

Gelchromatography column scanning has been used to study the fractions of reduced hydrolyzed 99mTc, 99mTc-pertechnetate and 99mTc-chelate in a 99mTc-glucoheptonate (GH) preparation. A stable high labelling yield of 99mTc-GH complex in the radiopharmaceutical has been obtained with a concentration of 40-50 mg of glucoheptonic acid-calcium salt and not less than 0.45 mg of SnCl2 2 H2O at an optimal pH between 6.5 and 7.0. The stability of the complex has been found significantly affected when sodium hydroxide solution was used for the pH adjustment. However, an alternative procedure for final pH adjustment of the preparation has been investigated providing a stable complex for the usual period of time prior to the injection. The organ distribution and the blood clearance data of 99mTc-GH in rabbits were relatively similar to those reported earlier. The mean concentration of the radiopharmaceutical in both kidneys has been studied in normal subjects for one hour with a scintillation camera and the results were satisfactory.

scholarly journals The force effects of two types of polyethylene terephthalate glyc-olmodified clear aligners immersed in artificial saliva

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Biao Xiang ◽  
Xingxing Wang ◽  
Gang Wu ◽  
Yichen Xu ◽  
Menghan Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Polyethylene Terephthalate ◽  
Artificial Saliva ◽  
Orthodontic Force ◽  
The Mean ◽  
The Stability ◽  
Scanning Electron

AbstractNumerous factors can influence the force exerted by clear aligners on teeth. This study aimed to investigate the stability of the force delivered by two different material appliances. 90 clear aligners with 2 materials and three different activations were designed and fabricated. Then, a device was employed to measure the force generated by the two types of PET-G material appliances immersed in artificial saliva for 0, 3, 7, 10, 14 days. Scanning electron microscopy was applied to observe the morphologic alterations on the aligner surfaces, respectively. The forces generated by different activation appliance exhibited differently, 0.0 mm < 0.1 mm < 0.2 mm. In addition, increasing the immersion times and the orthodontic force also decreased, but the forces decreased differently. Compared with the forces of conventional PETG appliances with 0.20 mm activation, the modified PETG appliances with the same activation exhibited significantly higher mean force. When comparing the mean force for modified PETG appliances after 10 and 14 days with conventional PETG appliances, the delivery forces exhibited significant differences (P < 0.05). The force delivered by both materials decreased obviously following artificial saliva immersion, and the force generated by modified aligners exhibited better stability than conventional aligners.

Symptomatic osteonecrosis of the hip and knee in patients with systemic lupus erythematosus: Prevalence, pattern, and comparison of natural course

Lupus ◽  
2021 ◽  
pp. 096120332110310
Author(s):  
Mehmet Ersin ◽  
Mehmet Demirel ◽  
Mehmet Ekinci ◽  
Lezgin Mert ◽  
Çiğdem Çetin ◽  
...  
Keyword(s):  
Systemic Lupus Erythematosus ◽  
Rheumatic Diseases ◽  
Lupus Erythematosus ◽  
Bone Structure ◽  
Survival Rates ◽  
Knee Joints ◽  
Joint Involvement ◽  
Systemic Lupus ◽  
Kaplan Meier ◽  
The Mean

Objective Osteonecrosis (ON), also known as avascular necrosis, is characterized by the collapse of the architectural bone structure secondary to the death of the bone marrow and trabecular bone. Osteonecrosis may accompany many conditions, especially rheumatic diseases. Among rheumatic diseases, osteonecrosis is most commonly associated with systemic lupus erythematosus (SLE). We assessed prevalence and distribution pattern of symptomatic ON in patients with SLE and compare the natural courses of hip and knee ON. Methods 912 SLE patients admitted between 1981 and 2012 were reviewed. SLE patients with symptomatic ON were retrospectively identified both from the existing SLE/APS database. The prevalence of symptomatic ON was calculated; with ON, the joint involvement pattern was determined by examining the distribution of the joints involved, and then the data about the hip and knee joints were entered in the Kaplan-Meier analysis. Kaplan-Meier methods were used to calculate 5- and 10-year rates of ON-related hip (the hip group) and knee survival (the knee group). Results Symptomatic ON developed in various joints in 97 of 912 patients with SLE, and the overall prevalence of ON was detected as 10.6%. The mean age at the time of SLE and ON diagnoses were 27.9 ± 9.9 (14–53) and 34.2 ± 11.3 (16–62) years, respectively. The mean duration from diagnosis of SLE to the first development of ON was 70.7± 60.2 (range = 0–216) months. The most common site for symptomatic ON was the hips (68%, n=66), followed by the knees (38%, n = 37). According to Kaplan-Meier analysis, hip and knee joint survival rates associated with 5-year ON were 51% and 88%, and 10-year survival rates were 43% and 84%, respectively. Conclusion We observed that the prevalence of symptomatic ON in patients with SLE was 10.6%. With the estimated 10-year survival rates of 40% versus 84% for the hip and knee joints, respectively, hip involvement may demonstrate a more aggressive course to end-stage osteoarthritis than the knee involvement.

Effects of walking speed on the step-by-step control of step width

2018 ◽  
Vol 68 ◽  
pp. 78-83 ◽  
Author(s):  
Katy H. Stimpson ◽  
Lauren N. Heitkamp ◽  
Joscelyn S. Horne ◽  
Jesse C. Dean
Keyword(s):  
Walking Speed ◽  
Step Width ◽  
Step Control

scholarly journals Stability Control for Electric Vehicles with Four In-Wheel-Motors Based on Sideslip Angle

2021 ◽  
Vol 12 (1) ◽  
pp. 42
Author(s):  
Kun Yang ◽  
Danxiu Dong ◽  
Chao Ma ◽  
Zhaoxian Tian ◽  
Yile Chang ◽  
...  
Keyword(s):  
Electric Vehicles ◽  
Control Method ◽  
Sliding Mode ◽  
Stability Control ◽  
Torque Control ◽  
Wheel Load ◽  
Sideslip Angle ◽  
Distribution Method ◽  
Load Rate ◽  
The Stability

Tire longitudinal forces of electrics vehicle with four in-wheel-motors can be adjusted independently. This provides advantages for its stability control. In this paper, an electric vehicle with four in-wheel-motors is taken as the research object. Considering key factors such as vehicle velocity and road adhesion coefficient, the criterion of vehicle stability is studied, based on phase plane of sideslip angle and sideslip-angle rate. To solve the problem that the sideslip angle of vehicles is difficult to measure, an algorithm for estimating the sideslip angle based on extended Kalman filter is designed. The control method for vehicle yaw moment based on sliding-mode control and the distribution method for wheel driving/braking torque are proposed. The distribution method takes the minimum sum of the square for wheel load rate as the optimization objective. Based on Matlab/Simulink and Carsim, a cosimulation model for the stability control of electric vehicles with four in-wheel-motors is built. The accuracy of the proposed stability criterion, the algorithm for estimating the sideslip angle and the wheel torque control method are verified. The relevant research can provide some reference for the development of the stability control for electric vehicles with four in-wheel-motors.

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