Using Passive End-Point Motion Constraints to Calibrate Robot Manipulators

1993 ◽  
Vol 115 (3) ◽  
pp. 560-566 ◽  
Author(s):  
M. R. Driels
Keyword(s):  
Robot Manipulator ◽  
Measurement Noise ◽  
Joint Angles ◽  
Kinematic Parameters ◽  
Motion Constraints ◽  
End Point ◽  
Ball Bar ◽  
Point Motion ◽  
Six Degree Of Freedom ◽  
Ancillary Equipment

The concept of using a method to constrain the endpoint of a serial linkage (such as a robot manipulator) in order to identify the kinematic parameters is appealing, since it no longer becomes necessary to use ancillary equipment to measure the pose, partial or otherwise. This means that the joint angles obtained from the manipulator and knowledge of the type of constraint, are all that is needed to perform the calibration. This concept is applied to the calibration of a six-degree-of-freedom manipulator by connecting its end point to a table by means of a ball bar. The kinematic equations of the manipulator and constraint are developed, and then used to simulate the calibration process in order to determine whether the noise level present in the measurements disrupts the convergence of the process, the effect of measurement noise on the accuracy of identification and the number of experimental observations needed. The acquisition of experimental data is then described, and the results of the identification are discussed. It is concluded that for certain types of kinematic structures, this method of calibration is particularly attractive since it is rapid, simple to perform, and requires very little precision equipment.

Discrete-Time LQR and H 2 Damping Control of Flexible Payloads Using a Robot Manipulator With a Wrist-Mounted Force/Torque Sensor

2000 ◽  
Author(s):  
Chunhao Joseph Lee ◽  
Constantinos Mavroidis
Keyword(s):  
Optimal Control ◽  
Discrete Time ◽  
Robot Manipulator ◽  
Control Design ◽  
Degree Of Freedom ◽  
Flexible Beam ◽  
Torque Sensor ◽  
Damping Control ◽  
Control Feedback ◽  
Six Degree Of Freedom

Abstract This paper presents robust and optimal control methods to suppress vibrations of flexible payloads carried by robotic systems. A new improved estimator in discrete-time H2 optimal control design based on the Kalman Filter predictor form is developed here. Two control design methods using state-space models, LQR and H2 Optimal Design, in discrete-time domain are applied and compared. The manipulator joint encoders and the wrist-mounted six-degree-of-freedom force/torque sensor provide the control feedback. A complete dynamic model of the robot/payload system is taken into account to synthesize the controllers. Experimental verifications of both methods are performed using a Mitsubishi five-degree-of-freedom robot manipulator that carries a flexible beam. It is shown that both methods damp out the vibrations of the payload very effectively.

scholarly journals Effect on hand kinematics when using assistive devices during activities of daily living

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7806
Author(s):  
Alba Roda-Sales ◽  
Margarita Vergara ◽  
Joaquín L. Sancho-Bru ◽  
Verónica Gracia-Ibáñez ◽  
Néstor J. Jarque-Bou
Keyword(s):  
Activities Of Daily Living ◽  
Daily Living ◽  
Peak Velocity ◽  
Assistive Devices ◽  
Joint Angles ◽  
Kinematic Parameters ◽  
Hand Kinematics ◽  
Instrumented Glove ◽  
Design Characteristics ◽  
Selection Of

Assistive devices (ADs) are products intended to overcome the difficulties produced by the reduction in mobility and grip strength entailed by ageing and different pathologies. Nevertheless, there is little information about the effect that the use of these devices produces on hand kinematics. Thus, the aim of this work is to quantify this effect through the comparison of kinematic parameters (mean posture, ROM, median velocity and peak velocity) while performing activities of daily living (ADL) using normal products and ADs. Twelve healthy right-handed subjects performed 11 ADL with normal products and with 17 ADs wearing an instrumented glove on their right hand, 16 joint angles being recorded. ADs significantly affected hand kinematics, although the joints affected differed according to the AD. Furthermore, some pattern effects were identified depending on the characteristics of the handle of the ADs, namely, handle thickening, addition of a handle to products that initially did not have one, extension of existing handles or addition of handles to apply higher torques. An overview of the effects of these design characteristics on hand kinematics is presented as a basis for the selection of the most suitable AD depending on the patient’s impairments.

scholarly journals Method for determining the kinematic parameters of the vertical rotor blades for the destruction of the tuberous layer

2020 ◽  
pp. 82-90
Author(s):  
V. A. Volsky V. A. ◽  
V. S. Bonchik
Keyword(s):  
Hydraulic Drive ◽  
Extreme Points ◽  
Geometric Shape ◽  
Kinematic Parameters ◽  
End Points ◽  
End Point ◽  
Vertical Rotor ◽  
Starting Point ◽  
The Absolute ◽  
Angle Of Rotation

Annotation Purpose. Development of a technique for determining the velocities of collision of the blades with the tuberous layer, the trajectory of movement, the magnitude and direction of the velocities of the most characteristic points. Methods. The research was carried out using the basic provisions of theoretical mechanics, statistics, probability theory, methods of differential calculations, mathematical modeling and applied programming. The studies were carried out on a specially designed laboratory installation using a vertical rotor hydraulic drive and strain gauge equipment mounted on a tractor, as well as a set of variable connecting plates for setting the machine operating modes. Results. The calculations of the absolute collision velocities of the blades of the lower and upper beaters of the vertical rotor at the start and end points, respectively, are performed. The geometric shape of the working surfaces and the direction of rotation for the extreme points of the outer contours of the blades of the lower and upper beaters of the vertical rotor of the potato harvester are substantiated. Conclusions. Using the above technique, as well as graphical dependences, we calculated the rational kinematic parameters of the blades of the lower and upper beaters of the vertical rotor, respectively, at the start and end points, where the greatest destruction of the tuber layer. For the lower beater blade, the absolute collision speed at the angle of rotation ωнt = 120° at the starting point = 1.6 m/s, at the end point – = 1.94 m/s. For the upper beater blade, the absolute collision speed at the angle of rotation ωвt = 120° at the starting point = 1.4 m/s, at the end point – = 1.92 m/s. Therefore, according to the specified rational kinematic parameters of the blades of the lower and upper beaters of the vertical rotor, it is possible to design the geometric shape of the surfaces of the crushing working bodies of potato harvesters. Keywords: blade, breaking surface, breasts, potatoes.

A New Measurement Device for Kinematic Calibration of Parallel Manipulators

2004 ◽  
Author(s):  
Abdul Rauf ◽  
Sung-Gaun Kim ◽  
Jeha Ryu
Keyword(s):  
Parallel Manipulators ◽  
Measurement Procedure ◽  
Initial Guess ◽  
Measurement Noise ◽  
Kinematic Calibration ◽  
Kinematic Parameters ◽  
End Effector ◽  
Experimental Procedure ◽  
New Device ◽  
Rotation Component

Kinematic calibration is a process that estimates the actual values of geometric parameters to minimize the error in absolute positioning. Measuring all the components of Cartesian posture assure identification of all parameters. However, measuring all components, particularly the orientation, can be difficult and expensive. On the other hand, with partial pose measurements, experimental procedure is simpler. However, all parameters may not be identifiable. This paper proposes a new device that can be used to identify all kinematic parameters with partial pose measurements. Study is performed for a 6 DOF (degree-of-freedom) fully parallel Hexa Slide manipulator. The device, however, is general and can be used for other parallel manipulators. The proposed device consists of a link with U joints on both sides and is equipped with a rotary sensor and a biaxial inclinometer. When attached between the base and the mobile platform, the device restricts the end-effector’s motion to 5 DOF and measures two position components and one rotation component of the end-effector. Numerical analyses of the identification Jacobian reveal that all parameters are identifiable. Computer simulations show that the identification is robust for the errors in the initial guess and the measurement noise. Intrinsic inaccuracies of the device can significantly deteriorate the calibration results. A measurement procedure is proposed and cost functions are discussed to prevent propagation of the inaccuracies to the calibration results.

scholarly journals Inverse kinematic solution of 6R robot manipulators based on screw theory and the Paden–Kahan subproblem

2018 ◽  
Vol 15 (6) ◽  
pp. 172988141881829 ◽  
Author(s):  
Rongbo Zhao ◽  
Zhiping Shi ◽  
Yong Guan ◽  
Zhenzhou Shao ◽  
Qianying Zhang ◽  
...  
Keyword(s):  
Inverse Kinematics ◽  
Matrix Theory ◽  
Screw Theory ◽  
Robot Manipulator ◽  
Inverse Kinematic ◽  
Kinematic Calibration ◽  
Kinematic Parameters ◽  
Kinematics Modeling ◽  
High Level ◽  
Kinematic Solution

The traditional Denavit–Hatenberg method is a relatively mature method for modeling the kinematics of robots. However, it has an obvious drawback, in that the parameters of the Denavit–Hatenberg model are discontinuous, resulting in singularity when the adjacent joint axes are parallel or close to parallel. As a result, this model is not suitable for kinematic calibration. In this article, to avoid the problem of singularity, the product of exponentials method based on screw theory is employed for kinematics modeling. In addition, the inverse kinematics of the 6R robot manipulator is solved by adopting analytical, geometric, and algebraic methods combined with the Paden–Kahan subproblem as well as matrix theory. Moreover, the kinematic parameters of the Denavit–Hatenberg and the product of exponentials-based models are analyzed, and the singularity of the two models is illustrated. Finally, eight solutions of inverse kinematics are obtained, and the correctness and high level of accuracy of the algorithm proposed in this article are verified. This algorithm provides a reference for the inverse kinematics of robots with three adjacent parallel joints.

Hand-held tools with complex kinematics are efficiently incorporated into movement planning and online control

2012 ◽  
Vol 108 (7) ◽  
pp. 1954-1964 ◽  
Author(s):  
Lee A. Baugh ◽  
Erica Hoe ◽  
J. Randall Flanagan
Keyword(s):  
Online Control ◽  
Movement Planning ◽  
Control Mechanisms ◽  
Movement Initiation ◽  
Reaching Movement ◽  
Hand Motion ◽  
Reversal Condition ◽  
End Point ◽  
Point Motion ◽  
Time Required

Certain hand-held tools alter the mapping between hand motion and motion of the tool end point that must be controlled in order to perform a task. For example, when using a pool cue, the motion of the cue tip is reversed relative to the hand. Previous studies have shown that the time required to initiate a reaching movement (Fernandez-Ruiz J, Wong W, Armstrong IT, Flanagan JR. Behav Brain Res 219: 8–14, 2011), or correct an ongoing reaching movement (Gritsenko V, Kalaska JF. J Neurophysiol 104: 3084–3104, 2010), is prolonged when the mapping between hand motion and motion of a cursor controlled by the hand is reversed. Here we show that these time costs can be significantly reduced when the reversal is instantiated by a virtual hand-held tool. Participants grasped the near end of a virtual tool, consisting of a rod connecting two circles, and moved the end point to displayed targets. In the reversal condition, the rod translated through, and rotated about, a pivot point such that there was a left-right reversal between hand and end point motion. In the nonreversal control, the tool translated with the hand. As expected, when only the two circles were presented, movement initiation and correction times were much longer in the reversal condition. However, when full vision of the tool was provided, the reaction time cost was almost eliminated. These results indicate that tools with complex kinematics can be efficiently incorporated into sensorimotor control mechanisms used in movement planning and online control.

Kinematic Characteristics of the Ski Jump Inrun: A 10-Year Longitudinal Study

2010 ◽  
Vol 26 (2) ◽  
pp. 196-204 ◽  
Author(s):  
Miroslav Janura ◽  
Lee Cabell ◽  
Milan Elfmark ◽  
František Vaverka
Keyword(s):  
Average Velocity ◽  
Joint Angles ◽  
Kinematic Parameters ◽  
Contributing Factors ◽  
World Cup ◽  
Kinematic Data ◽  
Straight Path ◽  
Body Segments ◽  
Ski Jumping ◽  
The World

The athlete’s inrun position affects the outcome for take-off in ski jumping. The purpose of this study was to examine the kinematic parameters between skiers’ adjacent body segments during their first straight path of the inrun. Elite ski jumpers participated in the study at the World Cup events in Innsbruck, Austria, during the years 1992 through 2001. A video image was taken at a right angle to the tracks of the K-110 (meter) jumping hill. Kinematic data were collected from the lower extremities and trunk of the athletes. Findings indicated that jumpers had diminished ankle and knee joint angles and increased trunk and hip angles over the 10 years. In recent years, the best athletes achieved a further length of their jumps, while they experienced slower inrun average velocity. These results are perhaps explained by several possible contributing factors, such as new technique of the jumper’s body kinematics, advancements in equipment technology, and somatotype of the jumpers.

DEVELOPMENT OF AN EOG BASED ROBOT MANIPULATOR AND END POINT DIRECTION CONTROL SYSTEM

2014 ◽  
Vol 22 (2) ◽  
pp. 293-299
Author(s):  
M. I Rusydi ◽  
Y. Mori ◽  
T. Okamoto ◽  
M. Sasaki ◽  
S. Ito
Keyword(s):  
Control System ◽  
Robot Manipulator ◽  
End Point ◽  
Direction Control
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