Compensation of discrete contact state errors in multi-fingered manipulation

2004 ◽  
Author(s):  
T. Schlegl
Keyword(s):  
Contact State ◽  
Discrete Contact

Investigation into Shear Experiment on Interface between Asphalt Pavement and Concrete Bridge Deck

2011 ◽  
Vol 197-198 ◽  
pp. 1435-1442
Author(s):  
Hong Fu Liu ◽  
Jian Long Zheng ◽  
Guo Ping Qian ◽  
Yun Yong Huang
Keyword(s):  
Shear Strength ◽  
Asphalt Pavement ◽  
Adhesive Layer ◽  
Interface Shear ◽  
Contact State ◽  
Modified Asphalt ◽  
Interface Contact ◽  
Concrete Bridge Deck ◽  
Sbs Modified Asphalt ◽  
Concrete Deck

This paper describes the laboratory measurement of shear interface properties between asphalt pavement and concrete bridge deck using the shear test. The main factors affecting shear strength are interface frictional resistance and adhesive stress from material of waterproof layer. Firstly, we simplify the whole system by considering the asphalt pavement as an elastic layer and the cement concrete deck a rigid base. And make a sensitivity analysis on interface contact state and the material modulus of waterproof layer. The maximum shear stress increases as interface contact state changes from continuous to smooth and as modulus of waterproof layer material decreases. Secondly, an interface shear experiment is conducted with the application of portable shear apparatus. With interface shear strength as evaluation indicator, shear strength of different interface treatments is arranged in descending order, i.e. cleaning up laitance and spreading aggregate between layers; only cleaning-up laitance; leaving the surface untreated. While the descending order for shear strength of different waterproof materials can be listed as follows: SBS modified asphalt, penetration grade of 70 asphalt. Therefore, based on the laboratory test results, it is recommended that before applying waterproof adhesive layer, laitance and dust on concrete deck surface should be cleaned up and keeping it dry. And the material for waterproof adhesive layer should be SBS modified asphalt with one-size aggregate of 4.75mm-9.5 mm spreading on.

scholarly journals Tactile Perception for Teleoperated Robotic Exploration within Granular Media

2021 ◽  
Vol 10 (4) ◽  
pp. 1-27
Author(s):  
Shengxin Jia ◽  
Veronica J. Santos
Keyword(s):  
Granular Media ◽  
Fluid Pressure ◽  
Tactile Sensor ◽  
Tactile Perception ◽  
Test Accuracy ◽  
Contact State ◽  
Buried Objects ◽  
Media Type ◽  
Additional Information ◽  
Internal Fluid

The sense of touch is essential for locating buried objects when vision-based approaches are limited. We present an approach for tactile perception when sensorized robot fingertips are used to directly interact with granular media particles in teleoperated systems. We evaluate the effects of linear and nonlinear classifier model architectures and three tactile sensor modalities (vibration, internal fluid pressure, fingerpad deformation) on the accuracy of estimates of fingertip contact state. We propose an architecture called the Sparse-Fusion Recurrent Neural Network (SF-RNN) in which sparse features are autonomously extracted prior to fusing multimodal tactile data in a fully connected RNN input layer. The multimodal SF-RNN model achieved 98.7% test accuracy and was robust to modest variations in granular media type and particle size, fingertip orientation, fingertip speed, and object location. Fingerpad deformation was the most informative modality for haptic exploration within granular media while vibration and internal fluid pressure provided additional information with appropriate signal processing. We introduce a real-time visualization of tactile percepts for remote exploration by constructing a belief map that combines probabilistic contact state estimates and fingertip location. The belief map visualizes the probability of an object being buried in the search region and could be used for planning.

Spatial Kinematic Analysis of Threaded Fastener Assembly

2005 ◽  
Vol 128 (1) ◽  
pp. 116-127 ◽  
Author(s):  
Stephen Wiedmann ◽  
Bob Sturges
Keyword(s):  
Design Space ◽  
Compliant Mechanisms ◽  
Contact Point ◽  
Three Dimensional ◽  
Vertical Movement ◽  
Initial Contact ◽  
Geometric Problem ◽  
Intelligent Sensor ◽  
Contact State ◽  
Contact Points

Compliant mechanisms for rigid part mating exist for prismatic geometries. A few instances are known of mechanisms to assemble screw threads. A comprehensive solution to this essentially geometric problem comprises at least three parts: parametric equations for nut and bolt contact in the critical starting phase of assembly, the possible space of motions between these parts during this phase, and the design space of compliant devices which accomplish the desired motions in the presence of friction and positional uncertainty. This work concentrates on the second part in which the threaded pair is modeled numerically, and contact tests are automated through software. Tessellated solid models were used during three-dimensional collision analysis to enumerate the approximate location of the initial contact point. The advent of a second contact point presented a more constrained contact state. Thus, the bolt is rotated about a vector defined by the initial two contact points until a third contact location was found. By analyzing the depth of intersection of the bolt into the nut as well as the vertical movement of the origin of the bolt reference frame, we determined that there are three types of contacts states present: unstable two-point, quasi-stable two-point, stable three point. The space of possible motions is bounded by these end conditions which will differ in detail depending upon the starting orientations. We investigated all potential orientations which obtain from a discretization of the roll, pitch, and yaw uncertainties, each of which has its own set of contact points. From this exhaustive examination, a full contact state history was determined, which lays the foundation for the design space of either compliant mechanisms or intelligent sensor-rich controls.

Research on Stiffness and Damping Characteristics of Fixed Oily Porous Materials Joint Interface

2011 ◽  
Vol 422 ◽  
pp. 575-579
Author(s):  
Chong Nian Qu ◽  
Liang Sheng Wu ◽  
Jian Feng Ma ◽  
Yi Chuan Xiao
Keyword(s):  
Porous Material ◽  
Porous Materials ◽  
Parallel Plate ◽  
Joint Interface ◽  
Force Model ◽  
Equivalent Stiffness ◽  
Contact State ◽  
Damping Characteristics ◽  
Stiffness And Damping ◽  
Damping Model

In this document, using the anti-squeezed force model in the narrow parallel plate when fluid is squeezed, the equivalent stiffness and damping model is derived. It is further verified that it can increase the stiffness and damping while there are oil between the joint interfaces theoretically. Because the contact state of oily porous material can divide into liquid and solid parts, the document supposes that it is correct and effective to think the stiffness and damping of the two parts as shunt connection.

scholarly journals Finite element solution of the three-dimensional system of equations of heat dynamics of friction and wear during single braking

2018 ◽  
Vol 10 (11) ◽  
pp. 168781401880864 ◽  
Author(s):  
Piotr Grzes
Keyword(s):  
Friction And Wear ◽  
Mutual Influence ◽  
Three Dimensional ◽  
Maximum Temperature ◽  
Dimensional System ◽  
System Of Equations ◽  
Sliding Velocity ◽  
Flash Temperature ◽  
Disk Brake ◽  
Discrete Contact

A three-dimensional numerical model of a disk brake to study temperature on a discrete contact of rough surfaces has been developed. It includes the system of equations formulated based on thermotribological postulates of heat dynamics of friction and wear with mutual influence of contact pressure, velocity, properties of materials, and temperature. Two approaches of calculation of the flash temperature and its influence on the maximum temperature during a single braking application were studied. Changes in the contact temperature, sliding velocity, and the thermomechanical wear during braking were shown and discussed. It was found that two of the examined variants of calculation of the flash temperature agree well for the three considered materials of the brake pads combined with the cast iron disk, at each initial sliding velocity in the range from 5 to 20 m s−1.

Nonlinear effect of tooth-slot transition on axial vibration, contact state and speed fluctuation in traveling wave ultrasonic motor

2017 ◽  
Vol 232 (19) ◽  
pp. 3424-3438 ◽  
Author(s):  
Dongsheng Zhang ◽  
Shiyu Wang
Keyword(s):  
Traveling Wave ◽  
Contact Stiffness ◽  
Nonlinear Phenomena ◽  
Axial Vibration ◽  
Contact State ◽  
State Response ◽  
Nonlinear Contact ◽  
Speed Fluctuation ◽  
Transition Force ◽  
Insight Into

The tooth-slot transition creates an axial excitation on traveling wave ultrasonic motors. It induces a rotor’s axial rigid vibration, which in turn affects the contact state and arouses speed fluctuation. To gain an insight into this problem, this work examines the relationships between the tooth-slot transition, axial vibration, nonlinear contact, and speed fluctuation. An analytical model governing rotor’s vibration is developed, where the transition force, nonlinear contact stiffness, and pre-pressure are included. The contact stiffness is demonstrated to decrease with an increase in stator’s vibration amplitude and it is approximated by polynomial fitting such that the nonlinear problem can be analytically solved. The primary, 1/2 subharmonic, and 2/1 superharmonic resonances are analyzed to determine the amplitude–frequency response and steady-state response. Nonlinear phenomena regarding the three types of resonances are identified. The interaction between the transition force, axial vibration, contact stiffness and speed fluctuation is investigated through a new contact model. The results imply that the rotor vibration induces rotating acceleration and leads to speed fluctuation. In addition, the rotor speed fluctuates in a similar fashion with the axial vibration.

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