Optimizing the Torque Distribution of a Redundantly Actuated Parallel Robot to Study the Temporomandibular Reaction Forces During Food Chewing

2020 ◽  
Vol 12 (5) ◽  
Author(s):  
Naser Mostashiri ◽  
Jaspreet Dhupia ◽  
Alexander Verl ◽  
John Bronlund ◽  
Weiliang Xu
Keyword(s):  
Inverse Dynamics ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Cost Functions ◽  
Measurement Tool ◽  
Redundancy Resolution ◽  
Theoretical Formulation ◽  
Temporomandibular Joints ◽  
Redundantly Actuated

Abstract Inverse dynamics solution of redundantly actuated parallel robots (RAPRs) requires redundancy resolution methods. In this paper, the Lagrange’s equations of the second kind are used to derive governing equations of a chewing RAPR. Jacobian analysis of the RAPR is presented. As redundancy resolutions, two different optimization cost functions corresponding to specific neuromuscular objectives, which are minimization of effort of the muscles of mastication and temporomandibular joints (TMJs) loads, are used to find the RAPR’s optimized actuation torque distributions. The actuation torques under the influence of experimentally determined dynamic chewing forces on molar teeth reproduced from a separate chewing experiment are calculated for realistic in vitro simulation of typical human chewing. These actuation torques are applied to the RAPR with a distributed-computed-torque proportional-derivative control scheme, allowing the RAPR’s mandible to follow a human subject’s chewing trajectory. TMJs loads are measured by force sensors, which are comparable with the computed loads from theoretical formulation. The TMJs loads for the two optimization cost functions are measured while the RAPR is chewing 3 g of peanuts on its left molars. Maximum and mean of the recorded loads on the left TMJ were higher in both cases. Moreover, the maximum and mean of the recorded loads on both TMJs were smaller for the cost function minimizing the TMJs loads. These results demonstrate validity of the model, suggesting the RAPR as a potential TMJ loads measurement tool to study the chewing characteristics of patients suffering from pain in TMJs.

DELTA: a simple and efficient parallel robot

Robotica ◽  
1990 ◽  
Vol 8 (2) ◽  
pp. 105-109 ◽  
Author(s):  
F. Pierrot ◽  
C. Reynaud ◽  
A. Fournier
Keyword(s):  
Inverse Kinematics ◽  
Research Team ◽  
Dynamic Models ◽  
Inverse Dynamics ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Kinematic Parameters ◽  
Mechanical Structure ◽  
Serial Robots ◽  
École Polytechnique

SummaryThe DELTA parallel robot, designed by an EPFL (Ecole Polytechnique Fédérale de Lausanne) research team, is a mechanical structure which has the advantage of parallel robots and ease of serial robots modeling. This paper presents solutions for a complete modeling of the DELTA parallel robot (direct and inverse kinematics, inverse statics, inverse dynamics), with few arithmetic and trigonometric operations. Our method is based on a satisfactory choice of kinematic parameters and on a few restricting hypotheses for the static and dynamic models. We give some details of each model, we present some computation results and we put the emphasis on some particular points, showing the capabilities of this mechanical structure.

Modeling of Dynamics and Model-Based Control of DELTA Direct-Drive Parallel Robot

1995 ◽  
Vol 7 (4) ◽  
pp. 344-352 ◽  
Author(s):  
Karol Miller ◽  
◽  
Boris S. Stevens ◽  
◽  
Keyword(s):  
Trajectory Tracking ◽  
Inverse Dynamics ◽  
Slight Modification ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Direct Application ◽  
Hamilton’S Principle ◽  
Direct Drive ◽  
Hamilton's Principle ◽  
Extended Space

The term ""Extended Space"" used in this article is hereby defined as a union of the operational and articulation spaces of a manipulator. The advantages in the use of such coordinates (extended space) in the description of DELTA robot is presented here and discussed in some detail. The emerging importance of parallel robots has necessitated an increased sophistication to achieve improved control. A method based on the direct application of the Hamilton's Principle in extended space, has been applied efficiently to solving the inverse problem of dynamics and implemented for real time application in the control law of the direct-drive version of DELTA parallel robot.1-3) The full dynamic model of this robot has been developed herein. The numerical efficiency and other benefits of this approach over the more classical Lagrange and Newton-Euler methods for the inverse dynamics problem solving are also briefly discussed. For similar models, the version obtained by the direct application of Hamilton's principle is found to possess 23% less mathematical operations than for the Lagrangebased model. Frictional effects. being very small in the direct-drive manipulator, are not included in the present Hamilton development but can be handled with a slight modification. Furthermore the acceleration information of the robot are not required as input states to the Hamilton model. The measurement of trajectory tracking performances for different controllers is conducted. The repeatability of the robot trajectory tracking is determined. The improvement obtained in the control algorithm's performance after the Hamilton implementation is proven to be conclusive.

Actuation-Coordinated Mobile Parallel Robots With Hybrid Mobile and Manipulation Function

2021 ◽  
Author(s):  
Dongming Gan ◽  
Jiaming Fu ◽  
Mo Rastgaar ◽  
Byung-Cheol Min ◽  
Richard Voyles
Keyword(s):  
Parallel Mechanism ◽  
Inverse Dynamics ◽  
Parallel Manipulators ◽  
Extreme Environment ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Mobile Manipulators ◽  
Large Area ◽  
Base Size ◽  
Inverse Dynamics Analysis

Abstract Mobile robots with manipulation capability are a key technology that enables flexible robotic interactions, large area covering and remote exploration. This paper presents a novel class of actuation-coordinated mobile parallel robots (ACMPRs) that utilize parallel mechanism configurations and perform hybrid moving and manipulation functions through coordinated wheel actuators. The ACMPRs differ with existing mobile manipulators by their unique combination of the mobile wheel actuators and the parallel mechanism topology through prismatic joint connections. The common motion of the wheels will provide the mobile function while their differentiation will actuate the parallel manipulator function. This new concept reduces the actuation requirement and increases the manipulation accuracy and mobile motion stability through the coordinated and connected wheel actuators comparing with existing mobile parallel manipulators. The relative wheel location on the base frame also enables a reconfigurable base size with variable moving stability on the ground. The basic concept and general type synthesis are introduced and followed by the kinematics and inverse dynamics analysis of a selected three limb ACMPR. A numerical simulation also illustrates the dynamics model and the motion property of the new mobile parallel robot. The work provides a basis for introducing this new class of robots for potential applications in surveillance, industrial automation, construction, transportation, human assistance, medical applications and other operations in extreme environment such as nuclear plants, Mars, etc.

Motion–Force Interaction Performance Analyses of Redundantly Actuated and Overconstrained Parallel Robots With Closed-Loop Subchains

2020 ◽  
Vol 142 (10) ◽  
Author(s):  
Qizhi Meng ◽  
Fugui Xie ◽  
Xin-Jun Liu
Keyword(s):  
Closed Loop ◽  
Interaction Analysis ◽  
Structural Parameters ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Load Carrying Capacity ◽  
Force Interaction ◽  
Load Carrying ◽  
Redundantly Actuated ◽  
Performance Analyses

Abstract Motion–force interaction performance analyses of redundantly actuated and overconstrained parallel robots with closed-loop subchains are an open problem considering two challenges: (a) how to take all the internal wrenches into account at the same level when the mobile platform suffers uncertain loads and (b) how to disclose the influence of the structural parameters inside the closed-loop subchains on the robot’s performance. To tackle this problem, based on the blocking-and-acting strategy, this paper proposes a new screw-based method to analyze the motion–force interaction performance of such parallel robots. Two aspects of performance are focused, i.e., the distal and proximal motion–force interactability. The two proposed indices focus on reflecting the load-carrying capacity and the motion-transmission capacity, respectively. To evaluate the comprehensive performance of the parallel robot at a certain pose, a local interaction index (LII) is defined as the minimum value of indices of the minimized distal and proximal interaction performance. The feasibility and validity of the proposed indices are illustrated by the motion–force interaction analysis of some redundantly actuated and overconstrained parallel robots with closed-loop subchains.

Directional Stiffness Modulation of Parallel Robots With Kinematic Redundancy and Variable Stiffness Joints

2019 ◽  
Vol 11 (5) ◽  
Author(s):  
Andrew L. Orekhov ◽  
Nabil Simaan
Keyword(s):  
Real Time ◽  
Variable Stiffness ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Redundancy Resolution ◽  
Kinematic Redundancy ◽  
Combined Use ◽  
Anchor Points ◽  
Variable Stiffness Actuators ◽  
Directional Stiffness

Parallel robots have been primarily investigated as potential mechanisms with stiffness modulation capabilities through the use of actuation redundancy to change internal preload. This paper investigates real-time stiffness modulation through the combined use of kinematic redundancy and variable stiffness actuators. A known notion of directional stiffness is used to guide the real-time geometric reconfiguration of a parallel robot and command changes in joint-level stiffness. A weighted gradient-projection redundancy resolution approach is demonstrated for resolving kinematic redundancy while satisfying the desired directional stiffness and avoiding singularity and collision between the legs of a Gough/Stewart parallel robot with movable anchor points at its base and with variable stiffness actuators. A simulation study is carried out to delineate the effects of using kinematic redundancy with or without the use of variable stiffness actuators. In addition, modulation of the entire stiffness matrix is demonstrated as an extension of the approach for modulating directional stiffness.

A learning-based control framework for cable-driven parallel robots with unknown Jacobians

2020 ◽  
Vol 234 (9) ◽  
pp. 1024-1036
Author(s):  
Hao Xiong ◽  
Lin Zhang ◽  
Xiumin Diao
Keyword(s):  
Neural Network ◽  
Control Strategy ◽  
Degrees Of Freedom ◽  
Inverse Dynamics ◽  
Parallel Robot ◽  
Joint Space ◽  
Parallel Robots ◽  
The Neural Network ◽  
Control Framework ◽  
In Series

Cable-driven parallel robots have been studied by many researchers in the past decades. The Jacobian of a cable-driven parallel robot may not be determined in some applications such as rehabilitation. In order to control the pose of a fully constrained cable-driven parallel robot with unknown Jacobian and driven by torque-controlled actuators, a learning-based control framework consisting of a robust controller and a neural network in series is proposed in this article. The neural network takes over the role of the Jacobian by mapping a wrench applied on the end-effector of the cable-driven parallel robot at a pose in the task space to a set of cable tensions in the joint space. In this way, the cable-driven parallel robot can be controlled by cable tensions derived from such a mapping, rather than solving the inverse dynamics problem based on the Jacobian. As an example, a control strategy is developed to demonstrate how the proposed control framework works. The control strategy includes a proportional–integral–derivative controller and a feedforward neural network. Simulation results show that the control strategy can successfully control a cable-driven parallel robot with four cables, three degrees of freedom, and unknown Jacobian.

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.

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.

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