Using a Maximum Error Statistic to Evaluate Measurement Errors in 3D Position and Orientation Tracking Systems

1993 ◽  
Vol 2 (4) ◽  
pp. 314-343 ◽  
Author(s):  
Ted Morris ◽  
Max Donath
Keyword(s):  
Relative Motion ◽  
Measurement Errors ◽  
Degrees Of Freedom ◽  
Motion Tracking ◽  
Computer Experiments ◽  
Maximum Error ◽  
Tracking Systems ◽  
3D Motion ◽  
Six Degrees Of Freedom ◽  
Error Statistic

One approach to tracking anatomical and robot joint motion consists of tracking the XYZ locations of multiple point targets that are attached to each of the moving segments and then computing the three translations and three orientation angles between adjoining segments. The complexity of such systems requires that we introduce a new conservative maximum error statistic to be used for evaluating the accuracy of 3D motion tracking systems. This paper addresses the various phenomena that contribute to measurement error when computing six degrees of freedom associated with the relative motion between the adjacent segments. The characteristics of these errors, common to many 3D motion tracking systems, were first determined by experimentation using one such system (MnSCAN). These and additional artifacts were then modeled in order to quantitatively evaluate their effects using the maximum error statistic. Based on these computer experiments, several relationships were identified that predict how each of these phenomena influences the predicted measurement of relative motion between bodies. These suggest where design emphasis should be placed in order to minimize the error in tracking the six degrees of freedom. The methodology and the conclusions based on these results can be applied to designing most six degree of freedom position and motion measurement systems.

scholarly journals A Numerical Model to Simulate the Motion of a Lifesaving Module During its Launching from the Ship’S Stern Ramp

2014 ◽  
Vol 21 (2) ◽  
pp. 34-40 ◽  
Author(s):  
Paweł Dymarski ◽  
Czesław Dymarski
Keyword(s):  
Numerical Model ◽  
Relative Motion ◽  
Degrees Of Freedom ◽  
Object Motion ◽  
Geometrical Parameters ◽  
High Complexity ◽  
3D Motion ◽  
Six Degrees Of Freedom ◽  
Rough Sea

Abstract The article presents a numerical model of object motion in six degrees of freedom (DoF) which is intended to be used to simulate 3D motion of a lifesaving module during its launching from a ship using a stern ramp in rough sea. The model, of relatively high complexity, takes into account both the motion of the ship on water in changing sea conditions, and the relative motion of the ramp with respect to the ship. The motion of the ramp changes and strongly depends on its constructional and geometrical parameters. The presented model takes into account the displacement of the submerged part of the ramp, as well as its damping in the water and the interaction with the module moving on it. The results of test simulation of a module launching from the ship in still water are included.

scholarly journals Ship-to-Ship State Observer Using Sensor Fusion and the Extended Kalman Filter

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Sondre Sanden Tørdal ◽  
Geir Hovland
Keyword(s):  
Kalman Filter ◽  
Sensor Fusion ◽  
Extended Kalman Filter ◽  
Relative Motion ◽  
Degrees Of Freedom ◽  
Load Transfer ◽  
Real Life ◽  
Fusion Algorithm ◽  
Six Degrees Of Freedom ◽  
Motion Estimate

In this paper, a solution for estimating the relative position and orientation between two ships in six degrees-of-freedom (6DOF) using sensor fusion and an extended Kalman filter (EKF) approach is presented. Two different sensor types, based on time-of-flight and inertial measurement principles, were combined to create a reliable and redundant estimate of the relative motion between the ships. An accurate and reliable relative motion estimate is expected to be a key enabler for future ship-to-ship operations, such as autonomous load transfer and handling. The proposed sensor fusion algorithm was tested with real sensors (two motion reference units (MRS) and a laser tracker) and an experimental setup consisting of two Stewart platforms in the Norwegian Motion Laboratory, which represents an approximate scale of 1:10 when compared to real-life ship-to-ship operations.

scholarly journals Optimal Geno-Fuzzy Lateral Control of Powered Parachute Flying Vehicles

Aerospace ◽  
2021 ◽  
Vol 8 (12) ◽  
pp. 400
Author(s):  
Hanafy M. Omar
Keyword(s):  
Vehicle Dynamics ◽  
Degrees Of Freedom ◽  
Fuzzy Logic Controller ◽  
Optimization Technique ◽  
Maximum Error ◽  
Steering Angle ◽  
Physical Constraints ◽  
Six Degrees Of Freedom ◽  
Fuzzy Membership Functions ◽  
Yaw Angle

In this work, we propose a systematic procedure to design a fuzzy logic controller (FLC) to control the lateral motion of powered parachute (PPC) flying vehicles. The design process does not require knowing the details of vehicle dynamics. Moreover, the physical constraints of the system, such as the maximum error of the yaw angle and the maximum allowed steering angle, are naturally included in the designed controller. The effectiveness of the proposed controller was assessed using the nonlinear six degrees of freedom (6DOF) mathematical model of the PPC. The genetic algorithm (GA) optimization technique was used to optimize the distribution of the fuzzy membership functions in order to improve the performance of the suggested controller. The robustness of the proposed controller was evaluated by changing the values of the parafoil aerodynamic coefficients and the initial flight conditions.

Experiments on Linear and Nonlinear Control of a Multi-DOF Parallel Mechanism

2003 ◽  
Author(s):  
Sandor Riebe ◽  
Heinz Ulbrich
Keyword(s):  
Degrees Of Freedom ◽  
Motion Tracking ◽  
Parallel Robot ◽  
Parallel Kinematics ◽  
Control Laws ◽  
Six Degrees Of Freedom ◽  
Position Accuracy ◽  
Nonlinear Approach ◽  
Linear Approach ◽  
Measurement Results

Parallel kinematics with multi degrees-of-freedom (DOF), like hexapod-systems, are mostly used in applications where high demands on position accuracy are required and/or high accelerations are needed. Adequate control concepts are essential in order to achieve the desired dynamic response. This paper deals with a comparative study of two structural different control concepts applied on a parallel robot with six degrees-of-freedom. The first one is a decentral linear approach and the second one is a multivariable nonlinear approach. The two concepts are presented and implemented on an experimental hexapod-system. In order to verify the used dynamic model comparisons between simulation and measurement results are shown. Finally, experiments have been carried out to compare the control laws with respect to their motion tracking performance.

scholarly journals Studies Evaluating Measurement Accuracy of CMS-JAW, a Jaw Motion Tracking Device with Six Degrees of Freedom Using an Ultrasonic Recording System

2008 ◽  
Vol 52 (3) ◽  
pp. 350-359 ◽  
Author(s):  
Takashi Uchida ◽  
Jun Sakai ◽  
Yasuhiro Okamoto ◽  
Tsukasa Watanabe ◽  
Tsuyoshi Kitagawa ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Motion Tracking ◽  
Measurement Accuracy ◽  
Recording System ◽  
Six Degrees Of Freedom ◽  
Tracking Device

Absolute accuracy analysis and improvement of a hybrid 6-DOF medical robot

2015 ◽  
Vol 42 (1) ◽  
pp. 44-53 ◽  
Author(s):  
Ahmed Joubair ◽  
Long Fei Zhao ◽  
Pascal Bigras ◽  
Ilian Bonev
Keyword(s):  
Measurement Errors ◽  
Degrees Of Freedom ◽  
Experimental Tests ◽  
Maximum Error ◽  
Calibration Method ◽  
Calibration Model ◽  
Medical Robot ◽  
Content Type ◽  
Observability Index ◽  
Forward Kinematic

Purpose – The purpose of this paper is to describe a calibration method developed to improve the accuracy of a six degrees-of-freedom medical robot. The proposed calibration approach aims to enhance the robot’s accuracy in a specific target workspace. A comparison of five observability indices is also done to choose the most appropriate calibration robot configurations. Design/methodology/approach – The calibration method is based on the forward kinematic approach, which uses a nonlinear optimization model. The used experimental data are 84 end-effector positions, which are measured using a laser tracker. The calibration configurations are chosen through an observability analysis, while the validation after calibration is carried out in 336 positions within the target workspace. Findings – Simulations allowed finding the most appropriate observability index for choosing the optimal calibration configurations. They also showed the ability of our calibration model to identify most of the considered robot’s parameters, despite measurement errors. Experimental tests confirmed the simulation findings and showed that the robot’s mean position error is reduced from 3.992 mm before calibration to 0.387 mm after, and the maximum error is reduced from 5.957 to 0.851 mm. Originality/value – This paper presents a calibration method which makes it possible to accurately identify the kinematic errors for a novel medical robot. In addition, this paper presents a comparison between the five observability indices proposed in the literature. The proposed method might be applied to any industrial or medical robot similar to the robot studied in this paper.

scholarly journals Application of a Jaw Motion Tracking Device That Measures Six Degrees of Freedom Using Optoelectronics

2006 ◽  
Vol 50 (2) ◽  
pp. 210-218 ◽  
Author(s):  
Takumi Ogawa ◽  
Yuko Shigeta ◽  
Eriko Ando ◽  
Shinya Hirai ◽  
Mayumi Suma ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Motion Tracking ◽  
Six Degrees Of Freedom ◽  
Tracking Device
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