Inverse Kinematic Model Research Articles

Definisanje inverznog kinematskog modela radnog uređaja bagera

Definisanje inverznog kinematskog modela radnog uređaja bagera

Uplift rates of marine terraces as a constraint on fault-propagation fold kinematics: Examples from the Hawkswood and Kate anticlines, North Canterbury, New Zealand

Marine terraces on growing fault-propagation folds provide valuable insight into the relationship between fold kinematics and uplift rates, providing a means to distinguish among otherwise non-unique kinematic model solutions. Here, we investigate this relationship at two locations in North Canterbury, New Zealand: the Kate anticline and Haumuri Bluff, at the northern end of the Hawkswood anticline. At both locations, we calculate uplift rates of previously dated marine terraces, using DGPS surveys to estimate terrace inner edge elevations. We then use Markov chain Monte Carlo methods to fit fault-propagation fold kinematic models to structural geologic data, and we incorporate marine terrace uplift into the models as an additional constraint. At Haumuri Bluff, we find that marine terraces, when restored to originally horizontal surfaces, can help to eliminate certain trishear models that would fit the geologic data alone. At Kate anticline, we compare uplift rates at different structural positions and find that the spatial pattern of uplift rates is more consistent with trishear than with a parallel-fault propagation fold kink-band model. Finally, we use our model results to compute new estimates for fault slip rates (~1–2m/ka at Kate anticline and 1–4m/ka at Haumuri Bluff) and ages of the folds (~1Ma), which are consistent with previous estimates for the onset of folding in this region. These results are consistent with previous work on the age of onset of folding in this region, provide revised estimates of fault slip rates necessary to understand the seismic hazard posed by these faults, and demonstrate the value of incorporating marine terraces in inverse fold kinematic models as a means to distinguish among non-unique solutions.

Kinematic Analysis of Planar Parallel Mechanism

The paper deals with kinematic model of parallel mechanism equipped with elastic members. The main aim is to determine the workspace of particular point of the mechanism in order to designing of whole mechanism for the future. Whole mechanisms should consist of several same segments which creates concept of serial mechanism. Since there is investigated parallel mechanism, at first has to be solved inverse kinematic model in order to obtain generalized variables, which are necessary for direct kinematic model. In the paper Jacobian matrix is derived for investigated mechanism. Then the algorithm for inverse kinematic model is described. The inverse kinematic model uses damped least squares method which appears as suitable method for our purposes. The results of inverse kinematic solution is consequently used for direct kinematic model, which is described by homogeneous transformation matrices. The planar parallel mechanism is simulated in software Matlab and the results are expressed in the graphs as well as our approach is discussed in the conclusion.

Fuzzy logic PD controller for trajectory tracking of an autonomous differential drive mobile robot (i.e. Quanser Qbot)

PurposeThe aim of this paper is to propose a robust robot fuzzy logic proportional-derivative (PD) controller for trajectory tracking of autonomous nonholonomic differential drive wheeled mobile robot (WMR) of the type Quanser Qbot.Design/methodology/approachFuzzy robot control approach is used for developing a robust fuzzy PD controller for trajectory tracking of a nonholonomic differential drive WMR. The linear/angular velocity of the differential drive mobile robot are formulated such that the tracking errors between the robot’s trajectory and the reference path converge asymptotically to zero. Here, a new controller zero-order Takagy–Sugeno trajectory tracking (ZTS-TT) controller is deduced for robot’s speed regulation based on the fuzzy PD controller. The WMR used for the experimental implementation is Quanser Qbot which has two differential drive wheels; therefore, the right/left wheel velocity of the differential wheels of the robot are worked out using inverse kinematics model. The controller is implemented using MATLAB Simulink with QUARC framework, downloaded and compiled into executable (.exe) on the robot based on the WIFI TCP/IP connection.FindingsCompared to other fuzzy proportional-integral-derivative (PID) controllers, the proposed fuzzy PD controller was found to be robust, stable and consuming less resources on the robot. The comparative results of the proposed ZTS-TT controller and the conventional PD controller demonstrated clearly that the proposed ZTS-TT controller provides better tracking performances, flexibility, robustness and stability for the WMR.Practical implicationsThe proposed fuzzy PD controller can be improved using hybrid techniques. The proposed approach can be developed for obstacle detection and collision avoidance in combination with trajectory tracking for use in environments with obstacles.Originality/valueA robust fuzzy logic PD is developed and its performances are compared to the existing fuzzy PID controller. A ZTS-TT controller is deduced for trajectory tracking of an autonomous nonholonomic differential drive mobile robot (i.e. Quanser Qbot).

Highly dexterous 2-module soft robot for intra-organ navigation in minimally invasive surgery.

For some surgical interventions, like the Total Mesorectal Excision (TME), traditional laparoscopes lack the flexibility to safely maneuver and reach difficult surgical targets. This paper answers this need through designing, fabricating and modelling a highly dexterous 2-module soft robot for minimally invasive surgery (MIS). A soft robotic approach is proposed that uses flexible fluidic actuators (FFAs) allowing highly dexterous and inherently safe navigation. Dexterity is provided by an optimized design of fluid chambers within the robot modules. Safe physical interaction is ensured by fabricating the entire structure by soft and compliant elastomers, resulting in a squeezable 2-module robot. An inner free lumen/chamber along the central axis serves as a guide of flexible endoscopic tools. A constant curvature based inverse kinematics model is also proposed, providing insight into the robot capabilities. Experimental tests in a surgical scenario using a cadaver model are reported, demonstrating the robot advantages over standard systems in a realistic MIS environment. Simulations and experiments show the efficacy of the proposed soft robot.

Research on Modeling Technology of Virtual Robot Based on LabVIEW

Because of the dangerous working environment, the underwater operation robot for nuclear power station needs manual teleoperation. In the process of operation, it is necessary to guide the position and orientation of the robot in real time. In this paper, the geometric modeling of the virtual robot and the working environment is accomplished by using SolidWorks software, and the accurate modeling and assembly of the robot are realized. Using LabVIEW software to read the model, and established the manipulator forward kinematics and inverse kinematics model, and realized the hierarchical modeling of virtual robot and computer graphics modeling. Experimental results show that the method studied in this paper can be successfully applied to robot control system.

A TE-E Optimal Planning Technique Based on Screw Theory for Robot Trajectory in Workspace

In the previous study, the minimum time and energy have been both considered to improve the efficiency and reliability of the manipulator operations. For further guaranteeing the tracking precision of end effector, a TE-E optimal planning technique is presented in this paper to optimize the trajectory of end effector. TE-E means two optimization objectives and one constraint condition: T is the total motion time, the first E is the total kinetic energy consumption and the second E is the motion error due to trajectory planning. In this technique, a local optimization process is completed to find a time-energy optimal trajectory, which could improve the movement efficiency and reliability. In this local process, the screw theory is used to obtain the forward and inverse kinematic models for simplifying the computation. The multi-solution situation in inverse kinematic is considered. The modified cubic spline interpolation is applied in the joint space to obtain the good motion stability. The objective function is defined as the weighted sum of two optimization objectives. The local optimal trajectory is obtained by using the particle swarm optimization (PSO) algorithm. Finally, the motion errors are considered as a condition to determine the number of the path points and obtain the final optimal trajectory that has good tracking precision. The simulation experiment for QJ-1 welding manipulator is completed to verify the reliability and validity of this technique. In the optimal trajectory, the relationships between the motion time and parameters for each joint show a good performance in the motion. The comparison of motion errors obtained by using the previous and presented methods proves the validity of this presented technique.

Synchronized motion control and precision positioning compensation of a 3-DOFs macro–micro parallel manipulator fully actuated by piezoelectric actuators

The macro–micro combined approach, as an effective way to realize trans-scale nano-precision positioning with multi-dimensions and high velocity, plays a significant role in integrated circuit manufacturing field. A 3-degree-of-freedoms (3-DOFs) macro–micro manipulator is designed and analyzed to compromise the conflictions among the large stroke, high precision and multi-DOFs. The macro manipulator is a 3-Prismatic-Revolute-Revolute (3-PRR) structure parallel manipulator which is driven by three linear ultrasonic motors. The dynamic model and the cross-coupling error based synchronized motion controller of the 3-PRR parallel manipulator are theoretical analyzed and experimental tested. To further improve the positioning accuracy, a 3-DOFs monolithic compliant manipulator actuated by three piezoelectric stack actuators is designed. Then a multilayer BP neural network based inverse kinematic model identifier is developed to perform the positioning control. Finally, by forming the macro–micro structure, the dual stage manipulator successfully achieved the positioning task from the point (2 mm, 2 mm, 0 rad) back to the original point (0 mm, 0 mm, 0 rad) with the translation errors in X and Y directions less than ±50 nm and the rotation error around Z axis less than ±1 μrad, respectively.

Cross-coupling control method for five-axis computer numerical control machine with dual rotary tables

The contour error cross-coupling control is very important to improve contour accuracy for the five-axis computer numerical control machine. The change in cutter orientation can cause the nonlinear motion of cutter tip, so the contour error calculation and compensation are very complex. For the five-axis computer numerical control machine with dual rotary tables, the forward kinematics model and inverse kinematics model are set up, and the influence laws of feed axis deviation to cutter tip deviation and cutter orientation deviation are studied. Then the simple and accurate calculation models for cutter tip contour error and cutter orientation contour error are established. Finally, the novel contour error cross-coupling control method based on kinematics model is developed. The experimental results show that the developed method can effectively improve contour accuracy of the five-axis computer numerical control machine.

Dual Quaternions as Constraints in 4D-DPM Models for Pose Estimation.

The goal of this research work is to improve the accuracy of human pose estimation using the Deformation Part Model (DPM) without increasing computational complexity. First, the proposed method seeks to improve pose estimation accuracy by adding the depth channel to DPM, which was formerly defined based only on red–green–blue (RGB) channels, in order to obtain a four-dimensional DPM (4D-DPM). In addition, computational complexity can be controlled by reducing the number of joints by taking it into account in a reduced 4D-DPM. Finally, complete solutions are obtained by solving the omitted joints by using inverse kinematics models. In this context, the main goal of this paper is to analyze the effect on pose estimation timing cost when using dual quaternions to solve the inverse kinematics.

Calibrate parallel machine tools by using interval type-2 fuzzy interpolation method

This paper is an extended research of our previous study, in which only type-1 fuzzy system was discussed, for a novel technique used in the pose error compensations for parallel machine tools calibration process based on an interval type-2 fuzzy error interpolation (IT2FEI) method. Robot calibrations can be classified into model-based and modeless methods. Either inverse or forward kinematic models need to be used in the traditional calibration methods to perform the identification and compensation of the pose errors for parallel machine tools. Instead of using a model, the proposed method presents a modeless technique combined with an interval type-2 fuzzy interpolation method to obtain the same or higher calibration accuracy when a small workspace is adopted. Simulated results show that not only the robot compensation accuracy can be improved but also the calibration process can be significantly simplified, and it is more suitable for practical applications.

Higher-order continuation method for the rigid-body kinematic design of compliant mechanisms

Compliant mechanisms are of great interest in precision engineering. In this paper, we propose a higher-order continuation method to help their rigid-body kinematic design. The method helps to investigate the choice of a mechanism configuration through the whole exploration of the workspace, and eases the kinematic analysis to avoid, or take advantage of, the vicinity of kinematic singularities. Such approach is relevant for planar and quasi-planar mechanisms that can be obtained with micro-manufacturing processes adapted to precision applications. The higher-order continuation method allows for a direct and accurate plotting of the input–output relationship of any mechanism by considering only its geometrical closed-loop equations, i.e. without the complex derivation of any analytical model. We show that these plots, called bifurcation diagrams, reveal essential information such as the joint velocity profile and the presence of singular configurations. Moreover, the continuous and accurate computation of the mechanism configuration in the vicinity of singularities provides detailed information about the kinematic behavior of the mechanism in its extreme positions. For the design of compliant mechanisms, the designer can advantageously use the bifurcation diagrams to evaluate the relevance of the selected mechanism, then to identify a configuration in order to obtain desired kinematic properties without the derivation of the inverse kinematic model (IKM) or the direct kinematic model (DKM). The method is exemplified with a 3 universal-joint and 3 spherical-joint mechanism (3-US), the IKM and DKM of which cannot be derived analytically. The latter has a large workspace and special kinematic behaviors consisting of a screw-like motion and a platform gyration, which have not been studied before and could lead to novel compliant devices.

Trajectory following and stabilization control of fully actuated AUV using inverse kinematics and self-tuning fuzzy PID.

In this work a design for self-tuning non-linear Fuzzy Proportional Integral Derivative (FPID) controller is presented to control position and speed of Multiple Input Multiple Output (MIMO) fully-actuated Autonomous Underwater Vehicles (AUV) to follow desired trajectories. Non-linearity that results from the hydrodynamics and the coupled AUV dynamics makes the design of a stable controller a very difficult task. In this study, the control scheme in a simulation environment is validated using dynamic and kinematic equations for the AUV model and hydrodynamic damping equations. An AUV configuration with eight thrusters and an inverse kinematic model from a previous work is utilized in the simulation. In the proposed controller, Mamdani fuzzy rules are used to tune the parameters of the PID. Nonlinear fuzzy Gaussian membership functions are selected to give better performance and response in the non-linear system. A control architecture with two feedback loops is designed such that the inner loop is for velocity control and outer loop is for position control. Several test scenarios are executed to validate the controller performance including different complex trajectories with and without injection of ocean current disturbances. A comparison between the proposed FPID controller and the conventional PID controller is studied and shows that the FPID controller has a faster response to the reference signal and more stable behavior in a disturbed non-linear environment.

Research on PSA-MFAC for a novel bionic elbow joint system actuated by pneumatic artificial muscles

A 3-DOF bionic elbow joint actuated by Pneumatic artificial muscle (PAM) was designed in this paper, and its inverse kinematics model was also established. Then, based on the Model-free adaptive control (MFAC) theory and the effects of control parameters to the control system, a Parameter self-adjust Model-free adaptive control (PSA-MFAC) strategy was proposed, and its adaptability for different control objects was also tested in simulation environment. Combined with the inverse kinematics model, motion control experiments of the bionic elbow joint were conducted in semi-physical platform. Compared with conventional MFAC and PID control algorithm, the experiment results strongly verified the improvement of PSA-MFAC control accuracy. The tracking accuracy of conventional MFAC and PID controller were 9.5 % and 15 %, respectively, in contrast, the PSA-MFAC controller was only 3.8 %. Moreover, complex dynamics modelling of the elbow joint and adjusting process of control parameters were neglected in PSA-MFAC control system.

BRIDGE - Behavioural reaching interfaces during daily antigravity activities through upper limb exoskeleton: Preliminary results.

People with neuromuscular diseases such as muscular dystrophy experience a distributed and evolutive weakness in the whole body. Recent technological developments have changed the daily life of disabled people strongly improving the perceived quality of life, mostly concentrating on powered wheelchairs, so to assure autonomous mobility and respiratory assistance, essential for survival. The key concept of the BRIDGE project is to contrast the everyday experience of losing functions by providing them of a system able to exploit the best their own residual capabilities in arm movements so to keep them functional and autonomous as much as possible. BRIDGE is composed by a light, wearable and powered five degrees of freedom upper limb exoskeleton under the direct control of the user through a joystick or gaze control. An inverse kinematic model allows to determine joints position so to track patient desired hand position. BRIDGE prototype has been successfully tested in simulation environment, and by a small group of healthy volunteers. Preliminary results show a good tracking performance of the implemented control scheme. The interaction procedure was easy to understand, and the interaction with the system was successful.

Supervised learning based on the self-organizing maps for forward kinematic modeling of Stewart platform

In this study, we propose an alternative technique for solving the forward kinematic problem of parallel manipulator which is designed based on generalized Stewart platform. The focus of this work is to predict a pose vector of a moving plate from a given set of six leg lengths. Since the data of parallel kinematics are usually available in the form of nonlinear dynamic system, several methods of system identification have been proposed in order to construct the forward kinematic model and approximate the pose vectors. Although these methods based on a multilayer perceptron (MLP) neural network provide acceptable results, MLP training suffers from convergence to local optima. Thus, we propose to use an alternative supervised learning algorithm called vector-quantized temporal associative memory (VQTAM) instead of MLP-based methods. VQTAM relying on self-organizing map architecture is used to build the mapping from the input space to the output space such that the training/testing datasets are generated from inverse kinematic model. The solutions from standard VQTAM are improved by an autoregressive (AR) model and locally linear embedding (LLE). The experimental results indicate that VQTAM with AR/LLE gives the outputs with nearly 100% prediction accuracy in the case of smooth data, while VQTAM + LLE provides the most accurate prediction on noisy data. Therefore, VQTAM + LLE is a very robust estimation method and can practically be used for solving the forward kinematic problem.

Effects of hip joint centre mislocation on gait kinematics of children with cerebral palsy calculated using patient-specific direct and inverse kinematic models

Joint kinematics can be calculated by Direct Kinematics (DK), which is used in most clinical gait laboratories, or Inverse Kinematics (IK), which is mainly used for musculoskeletal research. In both approaches, joint centre locations are required to compute joint angles. The hip joint centre (HJC) in DK models can be estimated using predictive or functional methods, while in IK models can be obtained by scaling generic models. The aim of the current study was to systematically investigate the impact of HJC location errors on lower limb joint kinematics of a clinical population using DK and IK approaches. Subject-specific kinematic models of eight children with cerebral palsy were built from magnetic resonance images and used as reference models. HJC was then perturbed in 6mm steps within a 60mm cubic grid, and kinematic waveforms were calculated for the reference and perturbed models. HJC perturbations affected only hip and knee joint kinematics in a DK framework, but all joint angles were affected when using IK. In the DK model, joint constraints increased the sensitivity of joint range-of-motion to HJC location errors. Mean joint angle offsets larger than 5° were observed for both approaches (DK and IK), which were larger than previously reported for healthy adults. In the absence of medical images to identify the HJC, predictive or functional methods with small errors in anterior-posterior and medial-lateral directions and scaling procedures minimizing HJC location errors in the anterior-posterior direction should be chosen to minimize the impact on joint kinematics.

Forward and Inverse Kinematic Analysis and Validation of the ABB IRB 140 Industrial Robot

Th e main goal of this paper is to derive the forward and inverse kinematic model of the ABB IRB 140 industrial manipulator. Denavit-Hartenberg analysis (DH) is presented to write the forward kinematic equations. Initially, a coordinate system is attached to each of the six links of the manipulator. Then, the corresponding four link parameters are determined for each link to construct the six transformation matrices ( that define each frame relative to the previous one. While, to develop the kinematics that calculates the required joint angles ( both geometrical and analytical approaches are used to solve the inverse kinematic problem. After introducing the forward and inverse kinematic models, a MATLAB code is written to obtain the solutions of these models. Then, the forward kinematics is validated by examining a set of known positions of the robot arm, while the inverse kinematics is checked by comparing the results obtained in MATLAB with a simulation in Robot Studio.

Design and analysis of a 3-DOF planar micromanipulation stage with large rotational displacement for micromanipulation system

Abstract. Flexure-based mechanisms have been widely used for scanning tunneling microscopy, nanoimprint lithography, fast servo tool system and micro/nano manipulation. In this paper, a novel planar micromanipulation stage with large rotational displacement is proposed. The designed monolithic manipulator has three degrees of freedom (DOF), i.e. two translations along the X and Y axes and one rotation around Z axis. In order to get a large workspace, the lever mechanism is adopted to magnify the stroke of the piezoelectric actuators and also the leaf beam flexure is utilized due to its large rotational scope. Different from conventional pre-tightening mechanism, a modified pre-tightening mechanism, which is less harmful to the stacked actuators, is proposed in this paper. Taking the circular flexure hinges and leaf beam flexures hinges as revolute joints, the forward kinematics and inverse kinematics models of this stage are derived. The workspace of the micromanipulator is finally obtained, which is based on the derived kinematic models.

Backlash characterization and position control of a robotic catheter manipulator using experimentally-based kinematic model

This paper deals with the problem of position control of a robot-assisted catheter manipulator for intracardiac interventions. Kinematic controllers based on the Jacobian inverse are not suitable for the catheter because of multiple singularities in the workspace and significant backlash of the system. To tackle these issues, first, the backlash of the system in axial translation and twist motion due to the interaction of the catheter with the veins through which it passes, are characterized. The effects of variations in clinical settings on the backlash parameters are identified through extensive experiments simulating the clinical procedure. Next, to properly compensate for the backlash behavior of the catheter distal shaft, an inverse kinematic model is proposed based on experimental data. A position controller is developed and implemented using the experimentally-based inverse kinematics and the identified inverse backlash model for the twist and axial motion. The results of experiments performed using a robotic catheter manipulation system show that with a proper choice of controller gains, the proposed scheme is able to guide the catheter tip to the goal with the desired behavior. The tracking performance of the controller has also been evaluated under the dynamic external force simulating the blood drag force. The empirical results demonstrate the improved performance of the proposed approach against the existing kinematic-based and uncompensated control schemes.