The relationship between controlled joint torque and end-effector force in underactuated robotic systems

Robotica ◽  
2010 ◽  
Vol 29 (4) ◽  
pp. 581-584 ◽  
Author(s):  
Jaeheung Park
Keyword(s):  
Jacobian Matrix ◽  
Joint Torque ◽  
Generalized Jacobian ◽  
End Effector ◽  
Joint Torques ◽  
Floating Base ◽  
Force Moment ◽  
Generalized Jacobian Matrix ◽  
The Relationship ◽  
Jacobian Inverse

SUMMARYThe generalized Jacobian matrix was introduced for dealing with end-effector control in space robots. One of the applications of this Jacobian is to be used in Jacobian transpose control to generate joint torques given end-effector position error. It would be misleading, however, to consider the transpose of this Jacobian as a mapping from end-effector force/moment to controlled joint torques for underactuated systems or floating base robots. This paper explains why it does not represent the mapping and provides a simple example. Later, the correct mapping is provided using the dynamically consistent Jacobian inverse and then a method to compute the actuated-joint torques is explained given the desired end-effector force. Finally, the effect of using the generalized Jacobian in the Jacobian transpose control is analyzed.

The Robust Adaptive Control of Free-Floating Space Manipulator Systems

2001 ◽  
Author(s):  
Chen Li ◽  
Liu Yanzhu
Keyword(s):  
Adaptive Control ◽  
Jacobian Matrix ◽  
Robust Adaptive Control ◽  
Dynamic Equations ◽  
Generalized Jacobian ◽  
Space Manipulator ◽  
Floating Base ◽  
Inertial Parameters ◽  
Control Scheme ◽  
Robust Adaptive

Abstract In this paper, the kinematics and dynamics of free-floating space manipulator systems are analyzed, and it is shown that the Jacobian matrix and the dynamic equations of the system are nonlinearly dependent on inertial parameters. In order to overcome the above problems, the system is modeled as under-actuated robot system, and the idea of augmentation approach is adopted. It is demonstrate that the augmented generalized Jacobian matrix and the dynamic equations of the system can be linearly dependent on a group of inertial parameters. Based on the results, the robust adaptive control scheme for free-floating space manipulator with uncertain inertial parameters to track the desired trajectory in workspace is proposed, and a two-link planar space manipulator system is simulated to verify the proposed control scheme. The proposed control scheme is computationally simple, because we choose to make the controller robust to the uncertain inertial parameters rather than explicitly estimating them online. In particular, it require neither measuring the position, velocity and acceleration of the floating base with respect to the orbit nor controlling the position and attitude angle of the floating base.

The Generalized Jacobian Matrix and the Manipulators Kinetostatic Properties

2010 ◽  
Author(s):  
Simone Cinquemani ◽  
Hermes Giberti ◽  
Giovanni Legnani
Keyword(s):  
Theoretical Analysis ◽  
Geometrical Structure ◽  
Jacobian Matrix ◽  
Drive System ◽  
Transmission Ratio ◽  
Generalized Jacobian ◽  
Generalized Jacobian Matrix

Manipulator kinetostatic performances are usually investigated considering only the geometrical structure of the robot, neglecting the effect of the drive system. In some circumstances this approach may leads to errors and mistakes. This may happen if the actuators are not identical to each other or when the employed transmission ratio are not identical and/or not constant. The paper introduces the so called “Generalized Jacobian Matrix” obtained identifying an appropriate matrix, generally diagonal, defined in order to: 1. properly weigh the different contributions of speed and force of each actuator. 2. describe the possible non-homogeneous behaviour of the drive system that depends on the configuration achieved by the robot. Theoretical analysis is supported by examples highlighting some of the most common mistakes done in the evaluation of a manipulator kinetostatic properties and how they can be avoided using the generalized jacobian matrix.

scholarly journals Simultaneous Floating-Base Estimation of Human Kinematics and Joint Torques

Sensors ◽  
2019 ◽  
Vol 19 (12) ◽  
pp. 2794 ◽  
Author(s):  
Claudia Latella ◽  
Silvio Traversaro ◽  
Diego Ferigo ◽  
Yeshasvi Tirupachuri ◽  
Lorenzo Rapetti ◽  
...  
Keyword(s):  
Motion Tracking ◽  
Tracking System ◽  
Joint Torque ◽  
Whole Body ◽  
Joint Torques ◽  
Floating Base ◽  
Fixed Base ◽  
Human Estimation ◽  
External Forces ◽  
Motion Tracking System

The paper presents a stochastic methodology for the simultaneous floating-base estimation of the human whole-body kinematics and dynamics (i.e., joint torques, internal and external forces). The paper builds upon our former work where a fixed-base formulation had been developed for the human estimation problem. The presented approach is validated by presenting experimental results of a health subject equipped with a wearable motion tracking system and a pair of shoes sensorized with force/torque sensors while performing different motion tasks, e.g., walking on a treadmill. The results show that joint torque estimates obtained by using floating-base and fixed-base approaches match satisfactorily, thus validating the present approach.

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