multiple rotational slip

2014 ◽  
pp. 898-898
Keyword(s):  
Rotational Slip

scholarly journals Anti-Slip Gait Planning for a Humanoid Robot in Fast Walking

2019 ◽  
Vol 9 (13) ◽  
pp. 2657 ◽  
Author(s):  
Fangzhou Zhao ◽  
Junyao Gao
Keyword(s):  
Walking Speed ◽  
Control Method ◽  
Humanoid Robots ◽  
Mass Model ◽  
Gait Planning ◽  
Fast Walking ◽  
Zero Moment ◽  
Constraint Method ◽  
Rotational Slip

Humanoid robots are expected to have broad applications due to their biped mobility and human-like shape. To increase the walking speed, it is necessary to increase the power for driving the joints of legs. However, the resulting mass increasing of the legs leads to a rotational slip when a robot is walking fast. In this paper, a 3D three-mass model is proposed, in which both the trunk and thighs are regarded as an inverted pendulum, and the shanks and feet are considered as mass-points under no constraints with the trunk. Then based on the model, a friction constraint method is proposed to plan the trajectory of the swing leg in order to achieve the fastest walking speed without any rotational slip. Furthermore, the compensation for zero-moment point (ZMP) is calculated based on the 3D three-mass model, and the hip trajectory is obtained based on the compensated ZMP trajectory by using the preview control method, thus improving the robot’s overall ZMP follow-up effect. This planning method involves simple calculations but reliable results. Finally, simulations confirm that the rotational slip is avoided while stable and fast walking is realized, with free joints of the waist and arms, which then could be planned for other tasks.

scholarly journals Translational and rotational slip detection and control in robotic manipulation

1999 ◽  
Vol 32 (2) ◽  
pp. 647-652 ◽  
Author(s):  
Claudio Melchiorri
Keyword(s):  
Robotic Manipulation ◽  
And Control ◽  
Rotational Slip ◽  
Slip Detection

Flexural Rotational Slip as the Main Deformation Process in the Torsion of Zinc Crystals

Nature ◽  
1955 ◽  
Vol 176 (4479) ◽  
pp. 460-461 ◽  
Author(s):  
A. D. WHAPHAM ◽  
H. WILMAN
Keyword(s):  
Deformation Process ◽  
Rotational Slip ◽  
Main Deformation

Surface re-orientation caused on metals by abrasion—its nature, origin and relation to friction and wear

1958 ◽  
Vol 247 (1250) ◽  
pp. 353-368 ◽  
Keyword(s):  
Fibre Orientation ◽  
Normal Load ◽  
Abrasive Particle ◽  
Electron Diffraction Investigation ◽  
Abrasive Particles ◽  
Emery Paper ◽  
Axis Parallel ◽  
First Time ◽  
Rotational Slip ◽  
Increasing Load

No adequate study of the surface structure of abraded poly crystalline metals has been made hitherto. The present electron-diffraction investigation of unidirectionally abraded beryllium and magnesium elucidates for the first time the characteristic nature and the origin of the fibre texture caused by abrasion, particularly its relation to the friction coefficient and the wear. The effects of a wide variety of conditions of load, speed, temperature and abrasive-particle size are determined. The main fibre orientation developed is of [001] type, the axis being inclined by an angle δ away from the outward normal, towards the direction from which the abrasive particles came. For beryllium δ is about 21°, the fibre axis being then along the resultant of the normal load W and the tangential frictional force F , at tan-1 μ = tan -1 0.38 to the normal. For magnesium δ= 22° and μ = 0*40. This main oblique fibre orientation is clearly a compres­sion texture, the (0001) slip lamellae becoming oriented normal to the compression axis. A very weak tendency of azimuthal preference round this axis, with <100> normal to the abrasion direction, was also observed in a few cases. With increasing load (above 1 Kg/cm 2 , using 0000 emery paper) on beryllium, in addition to the above main oblique texture the surface regions showed an increasing proportion of metal having a [001] fibre orientation with its axis normal to the surface, associated with the progressively greater amount of metal removed by shearing. Similar oblique and normal [001] fibre textures are developed by abrasion on single-crystal beryllium surfaces, showing clearly the extent of the lattice fragmentation. The region of transition to the underlying undisturbed crystal lattice indicates by its form that the deformation process involves flexural rotational slip on (0001), i. e. rotational slip on (0001) with simultaneous flexure of the slip lamellae about an axis parallel to (0001) not limited to the usual <210> direction.

scholarly journals Rancang Bangun dan Uji Kinerja Mesin Pembersihan dan Pengayakan Tipe-Grizzly Untuk Beras

2021 ◽  
Vol 14 (2) ◽  
pp. 65-75
Author(s):  
Aprilia Dila Wardiningrum ◽  
Agus Dharmawan ◽  
Soni Sisbudi Harsono ◽  
Siswoyo Soekarno
Keyword(s):  
Performance Test ◽  
Performance Testing ◽  
Work Capacity ◽  
Airflow Rate ◽  
Optimal Separation ◽  
And Performance ◽  
Main Components ◽  
Data Collections ◽  
Rotational Slip ◽  
Machine Work

Abstrak. Penelitian ini bertujuan untuk mengembangkan mesin pembersih dan pengayak tipe grizzly untuk beras sekaligus menguji kinerja mesin. Penelitian terdiri atas perancangan, perakitan, dan evaluasi kinerja mesin. Mesin yang dikembangkan memiliki 6 (enam) komponen utama, yaitu sumber dan transmisi tenaga putar, lubang pemasukan, unit pembersih beras, unit pengayak beras, lubang pengeluaran, dan kerangka mesin. Penelitian dilakukan menggunakan 3 (tiga) percobaan putaran, L (lambat), S (sedang), dan C (cepat) untuk mendapatkan data dari parameter pengukuran seperti kapasitas kerja, kecepatan putar mesin, laju isapan udara pada unit pembersih, slip putaran puli, dan persentase kehilangan bahan. Pada percobaan putaran L-S-C, yaitu 1654, 1817, dan 1979 rpm, menghasilkan laju isapan udara adalah 7,04, 7,79, dan 8,50 m/s. Slip putaran puli terjadi pada pulli 4 dengan nilai 3,27% tanpa sampal dan 1,70% dengan sampel; puli ini bertugas untuk menggetarkan ayakan grizzly 10-mesh. Kapasitas kerja pada 3 percobaan putaran (L-S-C) berturut-turut adalah 78,5, 81,6 dan 146,7 kg/jam. Pemisahan optimal dedak terjadi para percobaan putaran C sendangkan pemisahan menir terjadi pada percobaan L. Persentase kehilangan bahan tertinggi terjadi selama terjadi penurunan kecepatan putar yang mengakibatkan penurunan efektivitas kerja mesin.Design and Performance Test of Cleaning and Gryzzly-Type Sieving Machine for Rice Abstract. This research aimed to develop and a rice cleaning and grizzly-type sieving machine which also evaluates its performance. It consisted of designing, assembling, and performance evaluating of the machine. The desired machine was developed in six main components, i.e., power source, hopper, rice cleaner, rice siever, outlets, and machine frame. The research used three rotational speed treatments (Slow-Middle-Fast or L-S-C rotations) for data collections, whereas the parameters of performance testing consisted of work capacity, engine rotation speed, airflow rate, pulley rotational slip, and grain loss percentage. Engine rotation speeds at L-S-C treatments are 1654, 1817, and 1979 rpm and resulted in 7.04, 7.79, and 8.50 m/s, respectively, for airflow rates produced by the suction from a blower. The most significant rotational slip is occurred at Pulley-4 resulted in 3.27% (operating without samples) and 1.70% (operating with samples); this pulley transmitted rotational power to vibrate the 10-mesh grizzly sieve. The work capacities at L-S-C rotational treatments were 78.5, 81.6, and 146.7 kg/h, respectively. The optimal separation of brans was at C-rotational treatment, while the optimal separation of groats was at L-rotational treatment. The high percentage of grain loss occurred along with a reduction in speed that made the machine work ineffectively.

The study of crystal growth with the electron microscope IV. The nucleation and growth of n -propyl n -pentacontanoate

1955 ◽  
Vol 228 (1175) ◽  
pp. 539-548 ◽  
Keyword(s):  
Electron Microscope ◽  
Crystal Growth ◽  
Nucleation And Growth ◽  
Twist Boundary ◽  
Crystal Face ◽  
Screw Dislocations ◽  
Perfect Lattice ◽  
Lattice Disorder ◽  
Monomolecular Films ◽  
Rotational Slip

The study of long-chain paraffin derivatives in the electron microscope has been extended to include the fatty acid ester n -propyl n -pentacontanoate, n -C 53 H 106 o 2 . Examination of crystals prepared by previously described methods has given information on two further aspects of crystal growth. In the first place micrographs have been obtained at a much earlier stage in the growth of the crystals, before recognizable growth-steps have developed. It would appear that growth arises from sheet nuclei consisting of small condensed monomolecular films of 0.25 to 20μ 2 area. Screw dislocations arise at the edge of these sheets through the condensation of molecules in positions of incomplete lattice register. Growth thereafter continues around these dislocation centres, and the resultant spiral is built in towards the centre of the crystal face. This information modifies the Frank (1951) concept of a buckling mechanism for the formation of screw dislocations in crystals, since it places the emphasis on the importance of edge condensation in the formation of lattice disorder and minimizes the importance of strain in the growing perfect lattice. The second finding has been that these crystals frequently occur with a twist boundary parallel to {001}. This effect cannot properly be described as rotational slip of the type discussed by Wilman (1951), since it does not arise through deformation of an already formed crystal but occurs during growth itself. This twist boundary is penetrated by a screw dislocation or by a group of screw dislocations.

Twist boundaries and rotational slip in ZnS

1968 ◽  
Vol 18 (154) ◽  
pp. 753-762 ◽  
Author(s):  
B. K. Daniels
Keyword(s):  
Rotational Slip ◽  
Twist Boundaries
Sign in / Sign up

Export Citation Format

Share Document