Identification of Parameters for a Stewart Platform-based Force/Torque Sensor

In this paper, neural networks are presented to solve the inverse kinematic models of continuum robots. Firstly, the forward kinematic models are calculated for variable curvature continuum robots. Then, the forward kinematic models are implemented in the neural networks which present the position of the continuum robot’s end effector. After that, the inverse kinematic models are solved through neural networks without setting up any constraints. In the same context, to validate the utility of the developed neural networks, various types of trajectories are proposed to be followed by continuum robots. It is found that the developed neural networks are powerful tool to deal with the high complexity of the non-linear equations, in particular when it comes to solving the inverse kinematics model of variable curvature continuum robots. To have a closer look at the efficiency of the developed neural network models during the follow up of the proposed trajectories, 3D simulation examples through Matlab have been carried out with different configurations. It is noteworthy to say that the developed models are a needed tool for real time application since it does not depend on the complexity of the continuum robots' inverse kinematic models.

Chapter 3 - Description and modeling of experimental platforms

In this paper, a dual quaternion-based methodology for computing the forward and inverse kinematic models for a serial manipulator is presented. A dual quaternion-based forward kinematics model is developed for the Kuka LBR IIWA 7 R800 cobot. An inverse kinematics model is developed that uses dual quaternion differential kinematics and includes Jacobian transpose and damped least squares methods for determining Jacobian pseudo-inverse. Implementation of these methods on a given trajectory shows that, compared to damped least squares, the Jacobian transpose method is faster, but is less immune to singularity and gives more jerky motions.

Musculoskeletal disorders are major concern globally not just for the pain and suffering by the individual but also due to its adverse impact on the economy of the individual and the society. This results in productivity loss in both manufacturing and service sector, which has an adverse impact over the economy. The main aim of this work is to design and test an upper body exoskeleton arm that will be used for empowering the able-bodied, i.e., healthy users. The exoskeleton arm is intended to power or amplify the ability of the human elbow. Inverse dynamic model of the system is simulated through kinematic analysis and workspace analysis. The mathematical model developed by MATLAB is validated using ADAMS simulation tool. The obtained model is used to analyze the assistive torque requirements and position analysis of each task defined in the problem statement. Finally, the forward kinematic model, the inverse kinematic model, and the workspace analysis of the system are done which is universally flexible with respect to the dynamic parameters of the material used.

A 5 degree of freedom parallel mechanism with 6 branched redundant actuators is proposed. The mechanism is composed of 4 -SPS and 2-RPS kinematic branches. The mechanism can achieve three rotational and two translational motion. The performance of the forward and inverse kinematics, singularity and workspace, is analyzed, firstly, using the vector algebra method and Newton iteration method, the forward and inverse kinematics model were obtained from numerical solution and analytic solution; on this basis, get the Jacobian matrix of mechanism, and on the basis of the three kinds of performance parameters of matrix the singularity of the mechanism was analyzed; finally with the help of Monte Carlo method, obtaining the workspace of the mechanism. The related kinematic analysis will lay a theoretical foundation for the future study of the dynamics.

A fuzzy interpolation method is proposed to simplify the calibration process for parallel machine tools. 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 the fuzzy interpolation method to obtain the same or higher calibration accuracy when a small workspace is adopted.

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.

This research aims to optimize the trajectory of the foot-end in hexapod robots, with a primary focus on minimizing impact forces during ground contact and lowering overall energy consumption. By constructing both forward and inverse kinematic models, the corresponding kinematic equations for the robot’s foot-end motion were derived. These equations were employed to conduct a detailed analysis of the acceleration behaviour at the moment of touchdown. Through appropriate adjustment of trajectory equation parameters, a smoother acceleration curve during foot-ground interaction was achieved, thereby effectively suppressing impact forces. Simulation analysis confirms that the improved trajectory enhances the dynamic response of the foot-end, verifying the practicality and reliability of the proposed approach. The findings contribute valuable theoretical guidance for foot trajectory planning in hexapod robots and offer a new perspective on improving their stability and adaptability in complex terrain conditions.

Inverse Kinematic Model (IKM) is very crucial for real-time control of a robot for any application. Computing the IKM of continuum manipulators is a challenging task. Two types of methods exists; quantitative methods describing a model-based approach; and qualitative methods, based on learning approach. As quantitative methods are based on mathematical expression, they are more flexible for extension (increase in number of sections or collaboration between more than one manipulator). In this paper, two quantitative approaches based on Newton Raphson iterative method and Damped Least Square method, are proposed for Compact Bionic Handling Assistant (CBHA) manipulator to solve inverse kinematics directly using Forward Kinematic Model (FKM). Experimental validation is done for these methods as well as they are compared with the existing approaches named Hybrid approach and Neural Network based learning approach.

Development of an automatic control system for a hydraulic pruning robot

Reliability of joint kinematic calculations based on direct kinematic and inverse kinematic models in obese children

A new solution for machining with RA-PKMs: Modelling, control and experiments

Every year, stroke-induced upper limb impairment impacts millions of people worldwide, necessitating intensive rehabilitation to regain motor control. While conventional physical therapy and end-effector-based robots have been utilized, they often face limitations such as high labor costs, therapist fatigue, and an inability to control the redundancy of the human arm, which can lead to nonphysiologic compensatory movements. To address these challenges, this paper presents the development of the hybrid shoulder rehabilitation exoskeleton, an advanced iteration of the previous HYBRID-1 prototype. The hybridshoulder exoskeleton introduces two major design modifications based on performance evaluations and cable tension issues identified in the initial version. First, the shoulder girdle mechanism was redesigned by replacing the inverted slider-crank linkage with a planar crank-rocker four-bar linkage consisting of four revolute joints to better align with human anatomy. Second, a novel pretension mechanism was integrated into the Cable-Driven Parallel Mechanism toprevent cable derailment and maintain consistent tension using a system of rods, rollers, and compression springs.The design was first validated through a 3D-printed miniature model and CAD simulations, which confirmed the accuracy of the forward and inverse kinematic models. Subsequently, a real-scale prototype was manufactured featuring an adjustable shoulder cuff and additional base support to enhance structural stability for clinical applications. Initial assembly and preliminary testing indicate that these modifications provide a robust platform for intensive, task-specific rehabilitation. Future work will focus on performance testingwith healthy subjects to evaluate the system’s adaptability to various body parameters such as height and arm diameter. Keywords:Stroke Rehabilitation, Shoulder Exoskeleton, Shoulder Girdle Mechanism, Passive Pretension Mechanism, Crank-Rocker Four-Bar Linkage.

A five-degree-of-freedom hybrid parallel machine tool, composed of a 3-PRS parallel robot and an X-Y series table, is designed on geometry and analyzed on kinematics. The 3-PRS parallel robot consists of three serial chains and a fixed base and a moving platform which can be moved in a pose space corresponding to the three degrees of freedom. This kind of mechanism can be applied to measuring and machining through carrying test set or cutting tool on the moving platform. Both the forward and inverse kinematics models are established based on the kinematics analysis. By means of numerical analysis, a calculation example is performed to verify the correctness of the kinematics models.Keywordskinematics analysismachine tool3-PRSparallel robot

In this paper, the control system of intelligent grasping for a special operation manipulator is designed to complete disaster relief, fire fighting, explosive disposal and the like for replacing human beings. The control system of the special operation manipulator is needed to have the characteristics of multiple terminal functions, accurate end accuracy and high system reliability and redundancy within outdoor environment. It puts forward higher requirements for the manipulator performance and operator. After analyzing the work requirements of the manipulator, the D-H parameters and motion space is calculated for further research. The forward and inverse kinematics models are built to make the control system into reality. The target grasping is achieved by using the force and position hybrid control and single joint/end control methods. The intelligent recognition system based on machine learning is constructed. The simulation training based on machine learning is carried out by using the back image of the end camera of the manipulator to help the operator locate the target quickly and accurately. Finally the special operation manipulator is used to carry out the target intelligent grasping experiment based on visual guidance. The test results show the effectiveness of the control system design. Thereby it is suitable to be promoted to other robot or manipulator control system design.