ACTUATION AND MOTION CONTROL OF FLEXIBLE ROBOTS: SMALL DEFORMATION PROBLEM

2021 ◽  
pp. 1-41
Author(s):  
Ahmed A. Shabana ◽  
Zhengfeng Bai
Keyword(s):  
Motion Control ◽  
Shape Control ◽  
Degrees Of Freedom ◽  
Inverse Dynamics ◽  
Driving Forces ◽  
Small Deformation ◽  
Motion Trajectories ◽  
Deformation Problem ◽  
Joint Deformation ◽  
Functional Operation

Abstract This paper introduces a new computational approach for the articulated joint/deformation actuation and motion control of robot manipulators with flexible components. Oscillations due to small deformations of relatively stiff robot components can negatively impact the precision and the robot functional operation. Such oscillations, which cannot be ignored, are modeled in this study using the finite element (FE) floating frame of reference (FFR) formulation which employs two coupled sets of coordinates; the reference and elastic coordinates. The inverse dynamics, based on the widely used FFR formulation, leads to driving forces associated with the deformation degrees of freedom. Because of the link flexibility, two approaches can be considered in order to determine the actuation forces required to achieve the desired motion trajectories. These two approaches are the partially-constrained inverse dynamics (PCID) and the fully-constrained inverse dynamics (FCID). The FCID approach, which will be considered in future investigations and allows for motion and shape control, can be used to achieve the desired motion trajectories and suppress undesirable oscillations. The new small-deformation PCID approach introduced in this study, on the other hand, allows for achieving the desired motion trajectories, determining systematically the actuation forces and moments associated with the robot joint and elastic degrees of freedom, and avoiding deteriorations in the vibration characteristics as measured by the differences between the inverse- and forward-dynamics solutions. To this end, a procedure for determining the actuation forces associated with the deformation degrees of freedom is proposed and is exemplified using piezoelectric actuators.

The Dynamic Analysis of a 2-PRR Planar Parallel Mechanism

2005 ◽  
Vol 219 (9) ◽  
pp. 901-909 ◽  
Author(s):  
L-P Wang ◽  
J-S Wang ◽  
J Chen
Keyword(s):  
Parallel Mechanism ◽  
Parallel Manipulator ◽  
Degrees Of Freedom ◽  
Inverse Dynamics ◽  
Driving Forces ◽  
Inverse Dynamic ◽  
Inverse Dynamic Model ◽  
Planar Parallel Manipulator ◽  
Euler Approach ◽  
Motion Parameters

The article presents the inverse dynamics of a two-degrees-of-freedom planar parallel manipulator by the Newton-Euler approach. On the basis of the inverse dynamic model, the driving forces of actuators are simulated in different motion parameters. Further, the effects of inertia of each moving component to the driving forces are computed through the numerical method.

Optimizing motion trajectories of dextrous fingers by dynamic programming technique

Robotica ◽  
1992 ◽  
Vol 10 (5) ◽  
pp. 419-426 ◽  
Author(s):  
Ali Meghdari ◽  
Hassan Sayyaadi
Keyword(s):  
Dynamic Programming ◽  
Motion Control ◽  
Degrees Of Freedom ◽  
Optimization Technique ◽  
Dynamic Programming Algorithm ◽  
Programming Algorithm ◽  
Programming Technique ◽  
Motion Trajectories ◽  
Feasible Solutions ◽  
Dextrous Hand

SUMMARYAn optimization technique based on the well known Dynamic Programming Algorithm is applied to the motion control trajectories and path planning of multi-jointed fingers in dextrous hand designs. A three-fingered hand with each finger containing four degrees of freedom is considered for analysis. After generating the kinematics and dynamics equations of such a hand, optimum values of the joints torques and velocities are computed such that the finger-tips of the hand are moved through their prescribed trajectories with the least time or/and energy to reach the object being grasped. Finally, optimal as well as feasible solutions for the multi-jointed fingers are identified and the results are presented.

Revisiting the inverse dynamics of the Gough–Stewart platform manipulator with special emphasis on universal–prismatic–spherical leg and internal singularity

2012 ◽  
Vol 226 (10) ◽  
pp. 2422-2439 ◽  
Author(s):  
Mohamed Afroun ◽  
Antoine Dequidt ◽  
Laurent Vermeiren
Keyword(s):  
Parallel Manipulator ◽  
Degrees Of Freedom ◽  
Dynamic Models ◽  
Inverse Dynamics ◽  
Driving Forces ◽  
Stewart Platform ◽  
Inverse Dynamic ◽  
Computational Burden ◽  
Six Degrees Of Freedom ◽  
Leg Kinematics

This article discusses the dynamic modeling for control of Gough–Stewart platform manipulator with special emphasis on universal–prismatic–spherical leg kinematics. Inverse dynamic model of these six degrees of freedom parallel manipulator robots is reviewed, while complete dynamics with true kinematics of universal–prismatic–spherical legs is compared with several models found in the literature. Most existing models have not taken into account some of the legs kinematical effects, namely the legs angular velocity around their axes and the internal singularities due to passive joints; some other used a simplified parameterization to describe the leg kinematics. Furthermore, some kinetic assumption can be used to reduce the computational burden. This article shows the effect of all these simplifications on the driving forces by simulating the different dynamic models for a commercial manipulator and for different sets of geometric and dynamic parameters of manipulator.

Effects of Dynamic Model Errors in Task-Priority Operational Space Control

Robotica ◽  
2021 ◽  
pp. 1-12
Author(s):  
Paolo Di Lillo ◽  
Gianluca Antonelli ◽  
Ciro Natale
Keyword(s):  
Inverse Kinematics ◽  
Degrees Of Freedom ◽  
Inverse Dynamics ◽  
Null Space ◽  
Control Algorithms ◽  
Model Errors ◽  
Operational Space ◽  
Dynamic Level ◽  
Concurrent Tasks ◽  
Modeling Errors

SUMMARY Control algorithms of many Degrees-of-Freedom (DOFs) systems based on Inverse Kinematics (IK) or Inverse Dynamics (ID) approaches are two well-known topics of research in robotics. The large number of DOFs allows the design of many concurrent tasks arranged in priorities, that can be solved either at kinematic or dynamic level. This paper investigates the effects of modeling errors in operational space control algorithms with respect to uncertainties affecting knowledge of the dynamic parameters. The effects on the null-space projections and the sources of steady-state errors are investigated. Numerical simulations with on-purpose injected errors are used to validate the thoughts.

Three-dimensional asymmetric maximum weight lifting prediction considering dynamic joint strength

2021 ◽  
pp. 095441192098703
Author(s):  
Rahid Zaman ◽  
Yujiang Xiang ◽  
Jazmin Cruz ◽  
James Yang
Keyword(s):  
Experimental Data ◽  
Degrees Of Freedom ◽  
Inverse Dynamics ◽  
Three Dimensional ◽  
Optimization Method ◽  
Weight Lifting ◽  
Joint Torque ◽  
Maximum Weight ◽  
Angular Velocities ◽  
Asymmetric Lifting

In this study, the three-dimensional (3D) asymmetric maximum weight lifting is predicted using an inverse-dynamics-based optimization method considering dynamic joint torque limits. The dynamic joint torque limits are functions of joint angles and angular velocities, and imposed on the hip, knee, ankle, wrist, elbow, shoulder, and lumbar spine joints. The 3D model has 40 degrees of freedom (DOFs) including 34 physical revolute joints and 6 global joints. A multi-objective optimization (MOO) problem is solved by simultaneously maximizing box weight and minimizing the sum of joint torque squares. A total of 12 male subjects were recruited to conduct maximum weight box lifting using squat-lifting strategy. Finally, the predicted lifting motion, ground reaction forces, and maximum lifting weight are validated with the experimental data. The prediction results agree well with the experimental data and the model’s predictive capability is demonstrated. This is the first study that uses MOO to predict maximum lifting weight and 3D asymmetric lifting motion while considering dynamic joint torque limits. The proposed method has the potential to prevent individuals’ risk of injury for lifting.

Dynamic Analysis on a Cable-Driven Interventional Active Catheter Using Kane's Method Combined with Screw Theory

2014 ◽  
Vol 527 ◽  
pp. 140-145
Author(s):  
Da Xu Zhao ◽  
Bai Chen ◽  
Guo Zhong Shou ◽  
Yu Qi Gu
Keyword(s):  
Mathematical Model ◽  
Dynamic Analysis ◽  
Motion Control ◽  
Screw Theory ◽  
Driving Forces ◽  
Structure Design ◽  
Kinematics And Dynamics ◽  
Existing Problems ◽  
Blind Area ◽  
The Mathematical Model

In view of the existing problems of traditional interventional catheters, particularly poor activity, operation difficulty and mass blind area, a novel interventional catheter with a cable-driven active head-end is proposed, and a prototype was built to verify the performance. This paper deals with the kinematics and dynamics of the cable-driven prototype, a dynamic model based on Kanes method combined with screw theory was presented in this paper. According the mathematical model and the prototypes structure, the analysis of kinematics and dynamics of active head-end-end is done in the environment of Mathematica. The needed driving forces of every joint when the system moving along planned trajectory are calculated. The results can provide a basis for the structure design and motion control of the interventional active catheter.

On the Inherent Characteristics of the Dynamics of Robot Manipulators

1991 ◽  
Author(s):  
Q. Tu ◽  
J. Rastegar
Keyword(s):  
Path Length ◽  
Degrees Of Freedom ◽  
Inverse Dynamics ◽  
Robot Manipulators ◽  
Control Point ◽  
Coordinate Space ◽  
Relative Significance ◽  
Harmonic Content ◽  
Trajectory Pattern ◽  
Dynamics Models

Abstract The inherent characteristics of the (nonlinear) dynamics of robot manipulators are studied. The study is based on a new method, referred to as the trajectory pattern method. The inverse dynamics models of the manipulator are divided into classes of inverse dynamics models, each corresponding to a different trajectory pattern. For each trajectory pattern, the structure of the resulting inverse dynamics model is fixed and is used to study the characteristics of the dynamics of the manipulator by examining the harmonic content of the required actuation torques (forces) and the relative significance of each harmonic. The harmonic content of the actuating torques is shown to be a function of the path length in the joint coordinate space and the harmonic content of the selected trajectory pattern, but is independent of the number of degrees-of-freedom of the manipulator. The relative contribution of each harmonic is a function of the path length, direction of motion, the position of the path of motion within the workspace of the manipulator, and the magnitude of the fundamental frequency. The study provides a systematic approach to path and trajectory planning from the vibration control point of view. As an example, the characteristics of the dynamics of a spatial 3R manipulator is studied for motions with two different path lengths, starting from a specified point and extending in different directions.

Optimization in Trajectory Planning of Multi-Jointed Fingers in Dextrous Hand Designs

1991 ◽  
Author(s):  
A. Meghdari ◽  
H. Sayyaadi
Keyword(s):  
Dynamic Programming ◽  
Motion Control ◽  
Trajectory Planning ◽  
Degrees Of Freedom ◽  
Optimization Technique ◽  
Dynamic Programming Algorithm ◽  
Programming Algorithm ◽  
Kinematics And Dynamics ◽  
Feasible Solutions ◽  
Dextrous Hand

Abstract An optimization technique based on the well known Dynamic Programming Algorithm is applied to the motion control trajectories and path planning of multi-jointed fingers in dextrous hand designs. A three fingered hand with each finger containing four degrees of freedom is considered for analysis. After generating the kinematics and dynamics equations of such a hand, optimum values of the joints torques and velocities are computed such that the finger-tips of the hand are moved through their prescribed trajectories with the least time or/and energy to reach the object being grasped. Finally, optimal as well as feasible solutions for the multi-jointed fingers are identified and the results are presented.

Trajectory Tracking of Underactuated Multibody Systems

2011 ◽  
Author(s):  
Stefan Reichl ◽  
Wolfgang Steiner
Keyword(s):  
Trajectory Tracking ◽  
Multibody Systems ◽  
Degrees Of Freedom ◽  
Inverse Dynamics ◽  
Feedforward Control ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Differential Algebraic Equations ◽  
State Variables ◽  
Algebraic Equations

This work presents three different approaches in inverse dynamics for the solution of trajectory tracking problems in underactuated multibody systems. Such systems are characterized by less control inputs than degrees of freedom. The first approach uses an extension of the equations of motion by geometric and control constraints. This results in index-five differential-algebraic equations. A projection method is used to reduce the systems index and the resulting equations are solved numerically. The second method is a flatness-based feedforward control design. Input and state variables can be parameterized by the flat outputs and their time derivatives up to a certain order. The third approach uses an optimal control algorithm which is based on the minimization of a cost functional including system outputs and desired trajectory. It has to be distinguished between direct and indirect methods. These specific methods are applied to an underactuated planar crane and a three-dimensional rotary crane.

Quasi-human biped walking

Robotica ◽  
2005 ◽  
Vol 24 (2) ◽  
pp. 257-268 ◽  
Author(s):  
Hun-ok Lim ◽  
Sang-ho Hyon ◽  
Samuel A. Setiawan ◽  
Atsuo Takanishi
Keyword(s):  
Motion Control ◽  
Continuous Time ◽  
Degrees Of Freedom ◽  
Biped Robot ◽  
Humanoid Robots ◽  
Compensation Method ◽  
Biped Walking ◽  
Working Space ◽  
Physical Construction

Our goal is to develop biped humanoid robots capable of working stably in a human living and working space, with a focus on their physical construction and motion control. At the first stage, we have developed a human-like biped robot, WABIAN (WAseda BIped humANoid), which has a thirty-five mechanical degrees of freedom. Its height is 1.66 [m] and its weight 107.4 [kg]. In this paper, a moment compensation method is described for stability, which is based on the motion of its head, legs and arms. Also, a follow walking method is proposed which is based on a pattern switching technique. By a combination of both methods, the biped robot is able to perform dynamic stamping, walking forward and backward in a continuous time while someone is pushing or pulling its hand in such a way. Using WABIAN, human-fellow walking experiments are conducted, and the effectiveness of the methods are verified.

Sign in / Sign up

Export Citation Format

Share Document