Nonlinear dynamics of flexible links in planar parallel robots using a new beam element

2020 ◽  
Vol 26 (7-8) ◽  
pp. 475-489
Author(s):  
Mahdi Sharifnia
Keyword(s):  
Slope Angle ◽  
Main Idea ◽  
Parallel Robot ◽  
Beam Element ◽  
Parallel Robots ◽  
The Body ◽  
Inverse Dynamic ◽  
Two Parameters ◽  
Euler Bernoulli Beam ◽  
Similar Elements

In the present research, a previously presented beam element in planar static problems is extended to planar dynamic problems. As investigated in the previous work of the author, formulation of the presented Euler–Bernoulli beam element is simpler and the beam element more efficient than similar elements in large deflection problems. In the present element, the main idea is estimating the dimensions of the body in the deformed configuration, instead of estimating its absolute or relative positions. Therefore, two parameters, the length and slope angle of the beam centroid curve, are selected to be estimated by interpolating polynomials. To verify the efficiency of the element, obtained results for the flexible pendulum are compared with previous works. Because of the simple and efficient formulation of the element, it can be efficiently used for dynamic analysis of planar flexible linkages, and especially in flexible parallel robots, which are the main aims of the present research. Finally, the inverse dynamic of the flexible 3-RRR parallel robot is presented.

Kinematic Analysis of a Five-Legged Mobile Robot

2010 ◽  
Author(s):  
Muhammed R. Pac ◽  
Dan O. Popa
Keyword(s):  
Kinematic Analysis ◽  
Degrees Of Freedom ◽  
Parallel Robot ◽  
Parallel Robots ◽  
The Body ◽  
Legged Robots ◽  
Upper Body ◽  
Design Changes ◽  
Robot Performance ◽  
The Impact

Legged robots are more maneuverable, and can negotiate rough terrain much better than conventional locomotion using wheels. However, since the kinematic or dynamic analysis of such robots involves closed chains, it is typically more difficult to investigate the impact of design changes, such as the number, or the design of its legs, to robot performance. Most legged robots consist of 4 legs (quadrupeds) or 6 legs (hexapods). This paper discusses the kinematic analysis of an unconventional, symmetrical 5-legged robot with 2-DOF (Degrees Of Freedom) universal joints in each leg. The analysis was carried out in order to predict the mobility of the upper body platform, and investigate the number of robot actuators needed for mobility. The product of exponentials formulation with respect to the local coordinate frames is used to describe the twists of the joints. The analysis is based on the idea that the robot body platform along with the legs can be considered instantaneously as a parallel robot manipulating the ground. Hence, the analysis can be done using the Jacobian formulation of parallel robots. Simulation results confirm the mobility analysis that the robot can have at most 3-DOF for the body and that these freedoms are coupled rotations and translations in 3D space also with a dependence on the configuration of the robot.

scholarly journals Geometric Parameter Calibration for a Cable-Driven Parallel Robot Based on a Single One-Dimensional Laser Distance Sensor Measurement and Experimental Modeling

Sensors ◽  
2018 ◽  
Vol 18 (7) ◽  
pp. 2392 ◽  
Author(s):  
XueJun Jin ◽  
Jinwoo Jung ◽  
Seong Ko ◽  
Eunpyo Choi ◽  
Jong-Oh Park ◽  
...  
Keyword(s):  
Position Control ◽  
Uncertainty Modeling ◽  
Parallel Robot ◽  
Parallel Robots ◽  
The Body ◽  
Robot Kinematics ◽  
Kinematic Parameters ◽  
Body Frame ◽  
Geometric Uncertainty ◽  
Calibration Methods

A cable-driven parallel robot has benefits of wide workspace, high payload, and high dynamic response owing to its light cable actuator utilization. For wide workspace applications, in particular, the body frame becomes large to cover the wide workspace that causes robot kinematic errors resulting from geometric uncertainty. However, appropriate sensors as well as inexpensive and easy calibration methods to measure the actual robot kinematic parameters are not currently available. Hence, we present a calibration sensor device and an auto-calibration methodology for the over-constrained cable-driven parallel robots using one-dimension laser distance sensors attached to the robot end-effector, to overcome the robot geometric uncertainty and to implement precise robot control. A novel calibration workflow with five phases—preparation, modeling, measuring, identification, and adjustment—is proposed. The proposed calibration algorithms cover the cable-driven parallel robot kinematics, as well as uncertainty modeling such as cable elongation and pulley kinematics. We performed extensive simulations and experiments to verify the performance of the suggested method using the MINI cable robot. The experimental results show that the kinematic parameters can be identified correctly with 0.92 mm accuracy, and the robot position control accuracy is increased by 58%. Finally, we verified that the developed calibration sensor devices and the calibration methodology are applicable to the massive-size cable-driven parallel robot system.

scholarly journals Dynamic Parameter Identification of Overactuated Parallel Robots

2015 ◽  
Vol 137 (11) ◽  
Author(s):  
Sébastien Briot ◽  
Sébastien Krut ◽  
Maxime Gautier
Keyword(s):  
Parameter Identification ◽  
A Priori ◽  
Dynamic Parameter ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Current Loop ◽  
Dynamic Identification ◽  
Inverse Dynamic ◽  
Identification Process ◽  
Dynamic Parameter Identification

Offline robot dynamic identification methods are based on the use of the inverse dynamic identification model (IDIM), which calculates the joint forces/torques (estimated as the product of the known control signal (the input reference of the motor current loop) with the joint drive gains) that are linear in relation to the dynamic parameters, and on the use of the linear least squares technique to calculate the parameters (IDIM-LS technique). However, as actuation-redundant parallel robots are overactuated, their IDIM has an infinity of solution for the force/torque prediction, depending on the value of the desired overconstraint that is a priori unknown in the identification process. As a result, the IDIM cannot be used as it is for such a class of parallel robots. This paper proposes a procedure for the dynamic parameter identification of actuation-redundant parallel robots. The procedure takes advantage of two possible modified formulations for the IDIM of actuation-redundant robots that can be used for identification purpose. The modified IDIM formulations project some or all input torques/forces onto the robot bodies, thus leading to a unique solution of the model that can then be used in the identification process. A systematic and straightforward way to compute these modified IDIM is presented. The identification of the inertial parameters of a planar parallel robot with actuation redundancy, the DualV, is then carried out using these modified IDIM. Experimental results show the validity of the methods.

High-order singularities of 5R planar parallel robots

Robotica ◽  
2018 ◽  
Vol 37 (2) ◽  
pp. 233-245 ◽  
Author(s):  
Mustafa Özdemir
Keyword(s):  
Time Derivative ◽  
Parallel Manipulators ◽  
Parallel Robot ◽  
Singularity Analysis ◽  
Research Field ◽  
Parallel Robots ◽  
High Order ◽  
Inverse Dynamic ◽  
Active Research ◽  
Order Parallel

SUMMARYSingularity analysis of parallel manipulators is an active research field in robotics. The present article derives for the first time in the literature a condition under which a five-bar parallel robot encounters high-order parallel singularities. In this regard, by focusing on the planar 5R mechanism, a theorem is given in terms of the slope of its coupler curve at the parallel singular configurations. At high-order parallel singularities, the associated determinant vanishes simultaneously with at least its first-order time derivative. The determination of such singularities is quite important since in their presence, some special conditions should be satisfied for bounded inverse dynamic solutions.

On Force and Motion Control of Serial-Parallel Robots

1996 ◽  
Author(s):  
Shih-Liang Wang
Keyword(s):  
Control Algorithm ◽  
Virtual Work ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Joint Torque ◽  
Compact Structure ◽  
Serial Robots ◽  
S Matrix ◽  
Serial Robot ◽  
Rate Control Algorithm

Abstract A serial-parallel robot has the high stiffness and accuracy of a parallel robot, and a large workspace and compact structure of a serial robot. In this paper, the resolved force control algorithm is derived for serial-parallel robots, including a 3-articulated-arm platform robot, a linkage robot, and two cooperating serial robots. A S matrix is derived to relate joint torque to the external load. Using the principle of virtual work, S is used in resolved rate control algorithm to relate the tool velocity to joint rate. S can be easily expanded to the control of redundant actuation, and it can be used to interpret singularity. MATLAB is used to verify these control algorithms with graphical motion animation.

Drive System Sizing of a 6-DOF Parallel Robotic Platform

2014 ◽  
Author(s):  
Hermes Giberti ◽  
Davide Ferrari
Keyword(s):  
Optimal Solution ◽  
Parallel Robot ◽  
Drive System ◽  
Pareto Optimal ◽  
Hardware In The Loop ◽  
Motion Simulation ◽  
Inverse Dynamic ◽  
Kinematic Chains ◽  
Fixed Base ◽  
Parallel Kinematic

In this work, it is considered a 6-DoF robotic device intended to be applied for hardware-in-the-loop (HIL) motion simulation with wind tunnel models. The requirements have led to a 6-PUS parallel robot whose linkages consist of six closed-loop kinematic chains, connecting the fixed base to the mobile platform with the same sequence of joints: actuated Prism (P), Universal (U), and Spherical (S). As is common for parallel kinematic manipulators (PKMs), the actual performances of the robot depend greatly on its dimensions. Therefore, a kinematic synthesis has been performed and several Pareto-optimal solutions have been obtained through a multi-objective optimization of the machine geometric parameters, using a genetic algorithm. In this paper, the inverse dynamic analysis of the robot is presented. Then, the results are used for the mechanical sizing of the drive system, comparing belt- to screw-driven units and selecting the motor-reducer groups. Finally, the best compromise Pareto-optimal solution is definitely chosen.

Reduced Order Modeling and Direct Parameter Identification for a Complex Parallel Robot

2008 ◽  
Author(s):  
Jens Kroneis ◽  
Peter Mu¨ller ◽  
Steven Liu
Keyword(s):  
Parameter Identification ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Minimal Form ◽  
Linear Estimators ◽  
New Strategy ◽  
Reduction Methods ◽  
Verification Process ◽  
Dynamical Description ◽  
Solid Edge

In this paper a new strategy for dynamic modeling and parameter identification of complex parallel robots including parallel crank mechanisms is presented. Based on a model reduction strategy motivated by the structure of the parallel robot SpiderMill, kinematics and dynamics are derived in a compact form by applying the modified Denavit-Hartenberg method and the Newton-Euler approach. The obtained parameter-linear dynamical description is reduced to a parameter-minimal form using analytical and numerical reduction methods. Rigid body parameters of the model are identified using optimized trajectories and linear estimators. Through the whole modeling and verification process MSC.ADAMS and Solid Edge models of the demonstrator SpiderMill are used.

Simultaneous base and tool calibration for self-calibrated parallel robots

Robotica ◽  
2002 ◽  
Vol 20 (4) ◽  
pp. 367-374 ◽  
Author(s):  
Guilin Yang ◽  
I-Ming Chen ◽  
Song Huat Yeo ◽  
Wee Kiat Lim
Keyword(s):  
Parallel Robot ◽  
Parallel Robots ◽  
Sufficient Accuracy ◽  
Least Square ◽  
Mobile Platform ◽  
Calibration Model ◽  
End Effector ◽  
The World ◽  
Kinematic Transformation ◽  
Kinematic Errors

In this paper, we focus on the base and tool calibration of a self-calibrated parallel robot. After the self-calibration of a parellel robot by using the built-in sensors in the passive joints, its kinematic transformation from the robot base to the mobile platform frame can be computed with sufficient accuracy. The base and tool calibration, hence, is to identify the kinematic errors in the fixed transformations from the world frame to the robot base frame and from the mobile platform frame to the tool (end-effector) frame in order to improve the absolute positioning accuracy of the robot. Using the mathematical tools from group theory and differential geometry, a simultaneous base and tool calibration model is formulated. Since the kinematic errors in a kinematic transformation can be represented by a twist, i.e. an element of se(3), the resultant calibration model is simple, explicit and geometrically meaningful. A least-square algorithm is employed to iteratively identify the error parameters. The simulation example shows that all the preset kinematic errors can be fully recovered within three to four iterations.

scholarly journals Jumping in frogs: assessing the design of the skeletal system by anatomically realistic modeling and forward dynamic simulation

2002 ◽  
Vol 205 (12) ◽  
pp. 1683-1702 ◽  
Author(s):  
William J. Kargo ◽  
Frank Nelson ◽  
Lawrence C. Rome
Keyword(s):  
Degrees Of Freedom ◽  
The Body ◽  
Joint Torque ◽  
Rotational Degree ◽  
Skeletal System ◽  
Dynamic Simulations ◽  
Inverse Dynamic ◽  
Maximal Distance ◽  
Out Of Plane ◽  
Rotational Degrees Of Freedom

SUMMARY Comparative musculoskeletal modeling represents a tool to understand better how motor system parameters are fine-tuned for specific behaviors. Frog jumping is a behavior in which the physical properties of the body and musculotendon actuators may have evolved specifically to extend the limits of performance. Little is known about how the joints of the frog contribute to and limit jumping performance. To address these issues, we developed a skeletal model of the frog Rana pipiens that contained realistic bones, joints and body-segment properties. We performed forward dynamic simulations of jumping to determine the minimal number of joint degrees of freedom required to produce maximal-distance jumps and to produce jumps of varied take-off angles. The forward dynamics of the models was driven with joint torque patterns determined from inverse dynamic analysis of jumping in experimental frogs. When the joints were constrained to rotate in the extension—flexion plane, the simulations produced short jumps with a fixed angle of take-off. We found that, to produce maximal-distance jumping,the skeletal system of the frog must minimally include a gimbal joint at the hip (three rotational degrees of freedom), a universal Hooke's joint at the knee (two rotational degrees of freedom) and pin joints at the ankle,tarsometatarsal, metatarsophalangeal and iliosacral joints (one rotational degree of freedom). One of the knee degrees of freedom represented a unique kinematic mechanism (internal rotation about the long axis of the tibiofibula)and played a crucial role in bringing the feet under the body so that maximal jump distances could be attained. Finally, the out-of-plane degrees of freedom were found to be essential to enable the frog to alter the angle of take-off and thereby permit flexible neuromotor control. The results of this study form a foundation upon which additional model subsystems (e.g. musculotendon and neural) can be added to test the integrative action of the neuromusculoskeletal system during frog jumping.

Sign in / Sign up

Export Citation Format

Share Document