Contribution to the study of dynamics and dynamic control of robots interacting with dynamic environment

Robotica ◽  
2001 ◽  
Vol 19 (2) ◽  
pp. 149-161 ◽  
Author(s):  
Miomir Vukobratovic ◽  
Veljko Potkonjak ◽  
Vladimir Matijevic
Keyword(s):  
Contact Force ◽  
Dynamic Control ◽  
Dynamic Environment ◽  
Contact Dynamics ◽  
Simultaneous Stabilization ◽  
Robot System ◽  
Body Contact ◽  
Contact Points ◽  
Dynamics Modelling ◽  
Contact Tasks

The paper discusses some practical problems of contact dynamics. Modelling the dynamics of contact tasks is carried out in a completely general way. Two dynamic systems, active robot system and passive environment system are brought into contact and the relevant dynamics are analyzed. The effects are: rigid-body contact force, elastodynamics in contact zone, friction in contact points, etc. Simultaneous stabilization of contact force and position is obtained using New Dynamic Position/Force Control. The general model is then applied to some more concrete problems and the simulation results are presented.

A Contact Force Solution for Non-Colliding Contact Dynamics Simulation

2006 ◽  
Author(s):  
Inna Sharf ◽  
Yuning Zhang
Keyword(s):  
Rigid Body ◽  
Contact Force ◽  
Contact Point ◽  
Closed Form Solution ◽  
Rigid Body Dynamics ◽  
Contact Forces ◽  
Contact Dynamics ◽  
Dynamics Simulation ◽  
Friction Forces ◽  
Contact Points

Rigid-body impact modeling remains an intensive area of research spurred on by new applications in robotics, biomechanics, and more generally multibody systems. By contrast, the modeling of non-colliding contact dynamics has attracted significantly less attention. The existing approaches to solve non-colliding contact problems include compliant approaches in which the contact force between objects is defined explicitly as a function of local deformation, and complementarity formulations in which unilateral constraints are employed to compute contact interactions (impulses or forces) to enforce the impenetrability of the contacting objects. In this article, the authors develop a novel approach to solve the non-colliding contact problem for objects of arbitrary geometry in contact at multiple points. Similarly to the complementarity formulation, the solution is based on rigid-body dynamics and enforces contact kinematics constraints at the acceleration level. Differently, it leads to an explicit closed-form solution for the normal forces at the contact points. Integral to the proposed formulation is the treatment of tangential contact forces, in particular the static friction. These friction forces must be calculated as a function of microslip velocity or displacement at the contact point. Numerical results are presented for three test cases: 1) a thin rod sliding down a stationary wedge; 2) a cube rotating off the stationary wedge under application of an external moment and 3) the cube and the wedge both moving under application of a moment. To ascertain validity and correctness, the solutions to frictionless and frictional scenarios obtained with the proposed formulation are compared to those generated by using a commercial simulation tool MSC ADAMS.

scholarly journals Imitation learning-based framework for learning 6-D linear compliant motions

2021 ◽  
Author(s):  
Markku Suomalainen ◽  
Fares J. Abu-dakka ◽  
Ville Kyrki
Keyword(s):  
Contact Force ◽  
Free Space ◽  
Prior Information ◽  
Goal Area ◽  
Imitation Learning ◽  
Learning From Demonstration ◽  
End Effector ◽  
Localization Accuracy ◽  
Novel Method ◽  
Contact Tasks

AbstractWe present a novel method for learning from demonstration 6-D tasks that can be modeled as a sequence of linear motions and compliances. The focus of this paper is the learning of a single linear primitive, many of which can be sequenced to perform more complex tasks. The presented method learns from demonstrations how to take advantage of mechanical gradients in in-contact tasks, such as assembly, both for translations and rotations, without any prior information. The method assumes there exists a desired linear direction in 6-D which, if followed by the manipulator, leads the robot’s end-effector to the goal area shown in the demonstration, either in free space or by leveraging contact through compliance. First, demonstrations are gathered where the teacher explicitly shows the robot how the mechanical gradients can be used as guidance towards the goal. From the demonstrations, a set of directions is computed which would result in the observed motion at each timestep during a demonstration of a single primitive. By observing which direction is included in all these sets, we find a single desired direction which can reproduce the demonstrated motion. Finding the number of compliant axes and their directions in both rotation and translation is based on the assumption that in the presence of a desired direction of motion, all other observed motion is caused by the contact force of the environment, signalling the need for compliance. We evaluate the method on a KUKA LWR4+ robot with test setups imitating typical tasks where a human would use compliance to cope with positional uncertainty. Results show that the method can successfully learn and reproduce compliant motions by taking advantage of the geometry of the task, therefore reducing the need for localization accuracy.

Supercapacitor Dynamic Control Suite for Achieving High Transient State Power in Robot System

2021 ◽  
Author(s):  
Hao Deng ◽  
Hui Li ◽  
Minghui Xu ◽  
Chen Zhang ◽  
Ming Bai
Keyword(s):  
Dynamic Control ◽  
State Power ◽  
Transient State ◽  
Robot System

A novel model-based robust control design for collaborative robot joint module

2022 ◽  
pp. 095440622110547
Author(s):  
ShengChao Zhen ◽  
WangXu Cui ◽  
XiaoLi Liu ◽  
GuanJun Meng ◽  
Ye-Hwa Chen
Keyword(s):  
Numerical Simulation ◽  
Robust Control ◽  
Trajectory Tracking ◽  
Dynamic Performance ◽  
Dynamic Control ◽  
Robot System ◽  
Excellent Control ◽  
Robust Control Design ◽  
The Impact ◽  
Collaborative Robot

In order to reduce the impact of load and system parameter changes on the dynamic performance of collaborative robot joint module, a novel robust control algorithm is proposed in this paper to solve the problem of dynamic control of collaborative robot joint module trajectory tracking. The controller is composed of two parts: one is a nominal control term designed based on the dynamical model, aiming to stabilize the nominal robot system; the other is a robust control term based on the Lyapunov method, aiming to eliminate the influence of uncertainty on tracking performance, where the uncertainties include nonlinear friction, parameter uncertainty, and external disturbances. The Lyapunov minimax method is adopted to prove that the system is uniformly bounded and uniformly ultimately bounded. We performed numerical simulation and experimental validation based on an actual collaborative robot joint module experimental platform and the rapid controller prototype cSPACE. The numerical simulation and experimental results show that the controller has excellent control performance for the collaborative robot joint module and provides more accurate trajectory tracking under the influence of uncertainties.

scholarly journals Development and Application of a Tandem Force Sensor

Sensors ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 6042
Author(s):  
Zhijian Zhang ◽  
Youping Chen ◽  
Dailin Zhang
Keyword(s):  
Contact Force ◽  
Mechanical Model ◽  
Traction Force ◽  
Force Sensor ◽  
Teaching Experiment ◽  
Contact Forces ◽  
Contact Tasks

In robot teaching for contact tasks, it is necessary to not only accurately perceive the traction force exerted by hands, but also to perceive the contact force at the robot end. This paper develops a tandem force sensor to detect traction and contact forces. As a component of the tandem force sensor, a cylindrical traction force sensor is developed to detect the traction force applied by hands. Its structure is designed to be suitable for humans to operate, and the mechanical model of its cylinder-shaped elastic structural body has been analyzed. After calibration, the cylindrical traction force sensor is proven to be able to detect forces/moments with small errors. Then, a tandem force sensor is developed based on the developed cylindrical traction force sensor and a wrist force sensor. The robot teaching experiment of drawer switches were made and the results confirm that the developed traction force sensor is simple to operate and the tandem force sensor can achieve the perception of the traction and contact forces.

Determination of the Interference Geometry Between Two Convex Objects

2006 ◽  
Author(s):  
Lianzhen Luo ◽  
Meyer Nahon
Keyword(s):  
Contact Force ◽  
Contact Area ◽  
Contact Dynamics ◽  
Continuous Contact ◽  
Application Point ◽  
Haptic Interactions ◽  
Fitting Method ◽  
Best Fitting ◽  
Arbitrary Objects

The determination of the interference geometry between two arbitrary objects is an essential problem encountered in the simulation of continuous contact dynamics and haptic interactions. In these applications, with known material properties, the interbody contact force is only a function of the interference geometry between two objects. Here a theoretical basis and algorithms for the calculation of the interference geometry, such as overlap region, contact area and normal, and interference volume, are presented. Two methods to obtain the contact area and normal are analyzed: an area-weighted method and a best-fitting method. The geometric properties of the area-weighted method are presented and the degenerate cases related to both methods are discussed. Methods to calculate the application point of an interbody contact force are discussed. Some numerical simulation results are presented based on the implementation of the geometric algorithms, which are verified by comparison with hand calculation. The continuity of contact normal and its application point are demonstrated for a case in which the contacting objects smoothly move with respect to each other in the simulation.

The Development of an Autonomous Robot System for Patrolling in Multi-Floor Structured Environment

2012 ◽  
Vol 6 (1) ◽  
pp. 13-21 ◽  
Author(s):  
Tao He ◽  
◽  
Masashi Bando ◽  
Michele Guarnieri ◽  
Shigeo Hirose ◽  
...  
Keyword(s):  
Collision Avoidance ◽  
Dynamic Environment ◽  
Autonomous Robot ◽  
Stair Climbing ◽  
Inspection System ◽  
Robot System ◽  
Localization Scheme ◽  
Collision Avoidance System ◽  
Flat Ground ◽  
Surveillance Application

This paper introduces the design methods and organization of an automation robot system developed for security purpose. The unique roller wheel design makes the platform suited for stair climbing while still achieving a stable movement on a flat ground. The robot also features a localization scheme which is based on the observation of the ceiling and therefore can work properly in a highly dynamic environment. A collision avoidance system and an inspection system are proposed for realizing the autonomous surveillance application. Different experiments were carried out and the results confirmed the system’s robustness for patrolling inside multi-floor structured environment.

scholarly journals Computing Wrench Cones for Planar Rigid Body Contact Tasks

2002 ◽  
Vol 21 (12) ◽  
pp. 1053-1066 ◽  
Author(s):  
Devin J. Balkcom ◽  
J.C. Trinkle
Keyword(s):  
Rigid Body ◽  
Body Contact ◽  
Contact Tasks
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