Position control for haptic device based on discrete-time proportional integral derivative controller

Haptic devices had known as advanced technology with the goal is creating the experiences of touch by applying forces and motions to the operator based on force feedback. Especially in unmanned aerial vehicle (UAV) applications, the position of the end-effector Falcon haptic sets the velocity command for the UAV. And the operator can feel the experience vibration of the vehicle as to the acceleration or collision with other objects through a forces feedback to the haptic device. In some emergency cases, the haptic can report to the user the dangerous situation of the UAV by changing the position of the end-effector which is be obtained by changing the angle of the motor using the inverse kinematic equation. But this solution may not accurate due to the disturbance of the system. Therefore, we proposed a position controller for the haptic based on a discrete-time proportional integral derivative (PID) controller. A Novint Falcon haptic is used to demonstrate our proposal. From hardware parameters, a Jacobian matrix is calculated, which combines with the force output from the PID controller to make the torque for the motors of the haptic. The experiment was shown that the PID has high accuracy and a small error position.

Dynamic and Wrench-Feasible Workspace Analysis of a Cable-Driven Parallel Robot Considering a Nonlinear Cable Tension Model

Cable-driven parallel robots (CDPRs) have several advantages and have been widely used in many industrial fields, especially industrial applications that require high dynamics, high payload capacity, and a large workspace. In this study, a design model for a CDPR system was proposed, and kinematic and dynamic modeling of the system was performed. Experiments were carried out to identify the dynamic modulus of elastic cables based on the dynamic mechanical analysis (DMA) method. A modified kinematic equation considering cable nonlinear tension was developed to determine the optimal cable tension at each position of the end-effector, and the wrench-feasible workspace was analyzed at various motion accelerations. The simulation results show that the proposed CDPR system obtains a large workspace, and the overall workspace is satisfactory and unrestricted for moving ranges in directions limited by the X-axis and the Y-axis from −0.3 to 0.3 m and by the Z-axis from 0.1 to 0.7 m. The overall workspace was found to depend on the condition of acceleration as well as the moving ranges limited by the end-effector. With an increase in external acceleration, the cable tension distribution increased and reached a maximum in the case of 100 m/s2.

Kinematic Analysis and Motion Planning of Cable-Driven Rehabilitation Robots

In this study, a new cable-driven rehabilitation robot is designed, the overall design of the robot is given, and the kinematic equation of the lower limbs in the supine state of the human body is addressed. Considering that cable winders move along the rail brackets, the closed vector method is applied to establish the kinematic model of the robot, and the relationship between the human joint angle and the cable length change was deduced. Considering joint compliance, a fifth-order polynomial trajectory planning method based on an S-shaped curve is proposed by introducing an S-shaped velocity curve, and the changes in cable length displacement, velocity, and acceleration are simulated and analyzed. Three planning methods are compared based on two indices, and experimental verification is carried out on the rehabilitation experiment platform. The simulation and experimental results show that the trajectory planning method presents low energy consumption and strong flexibility, and can achieve better rehabilitation effect, which builds a good basis for the subsequent study of dynamics and control strategy.

TO THE PROBLEM OF DEVELOPING NEW METHODS FOR ESTIMATING THE MECHANISM OF FORMATION OF FOCAL ZONES OF CATASTROPHIC EVENTS IN CARBON BEDS

The article shows that the problem of safe mining is largely related to ideas about the mechanisms of interaction of nonlinear geomechanical and physicochemical mass-gas exchange processes in multiphase coal-rock massifs. For the first time, a complex of generalizing analytical, experimental laboratory and field studies at the regional level, carried out by the authors, made it possible to establish that in modern conditions, with the development of deep horizons, the role of rock pressure, temperature and geostructural factors, as well as the presence of an increasing influence of the seismic background from earthquakes and technological explosions. A numerical simulation method and an original experimental system for determining the regularity of the decay of this two-phase flow were developed by Chinese and Russian specialists taking into account the influence of the gas expansion energy on the propagation characteristics of a mixture of pulverized coal and gas. The analytical basis for describing the established deterministic relationships between the existing nonlinear geomechanical and physicochemical processes in stressed coal-bearing massifs was the establishment of an operator correspondence between the physicochemical equation of I. Langmuir and the kinematic equation of V.N. Oparin for pendulum waves.

Three Wheeled Omnidirecional Mobile Robot - Design and Implementation

This article presents a study of the resources necessary to providemovement and localization in three wheeled omnidirectionalrobots, through the detailed presentation of the mathematical proceduresapplicable in the construction of the inverse kinematic model,the presentation of the main hardware and software componentsused for the construction of a functional prototype, and the testprocedure used to validate the assembly.The results demonstrate that the developed prototype is functional,as well as the developed kinematic equation, given the smallerror presented at the end of the validation procedure.

Non-Rigid Rotating Motion Effect on Creep Behavior for Infinite Cylinders under Thermomechanical Loading

The effect of non-rigid motion on creep analysis for cylinders have been investigated. inner surface of the cylinder is exposed to a uniform heat flux and for cooling the outer surface of the cylinder an air steam is applied to it. The cylinder is subjected to a body force. That produced by rotating cylinder about its own axis. It is assumed the cylinder is not rigid. Therefore, using equations of equilibrium, stress–strain and kinematic equation, governed equation which includes redial displacement and creep strains, is obtained. The material creep constitutive model is defined by the Bailey-Norton time-dependent creep law. From a solution consisting of analytical solution and iteration method has been used to obtain history of stresses and deformations during creep evolution of rotating cylinders. Therefore, Prandtle-Ruess equation substituted in equilibrium equation in the rate form, the radial displacement rate is obtained for plane strain condition. To investigate the effect of non-rigidity, the non-rigidity parameter (ζ) is defined and its effect on the creep behavior of the structure is investigated. It was revealed that Considering the structure as rigid does neglect the amount of stresses and radial displacement. History of stresses and displacement during 20 years are studied and it is observed that the changes have not accrued in recent years. The effect of velocity is another parameter that is investigated its effect on structural behavior during the time. it was revealed that, velocity has significant effect on structural behavior which cause trend of variation behavior change from linear to polynomial curve.

Lightweight Extended Kalman Filter for MARG Sensors Attitude Estimation

<div> <div> <div> <p>Low-power consumption of orientation estimation using low-cost inertial sensors are crucial for all the applications which are resource constrained critically. This paper presents a novel Lightweight quaternion-based Extended Kalman Filter (LEKF) for orientation estimation for magnetic, angular rate and gravity (MARG) sensors. In this filter, with employing the quaternion kinematic equation as the process model, we derived a simplified measurement model to create the lightweight system model for Kalman filtering, where the measurement model works efficiently and the involved computation of measurement model is reduced. It’s later proved that the proposed filter saves time consumption. Further, due to that no linearization is involved for the proposed measurement model, the good performance would be guaranteed in theory. For the experiments, a commercial sensor for data collection and an optical system to provide reference measurements of orientation, namely Vicon, are utilized to investigate the performance of the proposed filter. Evaluation for different application scenarios are considered, which primarily includes human motion capture and the drone application. Results indicate that the proposed filter provides reliable performance for both applications. What’s more, the comparison experiment shows that the proposed filter provides better performance in terms of either attitude estimation accu- racy or computational time. </p> </div> </div> </div>

Lightweight Extended Kalman Filter for MARG Sensors Attitude Estimation

<div> <div> <div> <p>Low-power consumption of orientation estimation using low-cost inertial sensors are crucial for all the applications which are resource constrained critically. This paper presents a novel Lightweight quaternion-based Extended Kalman Filter (LEKF) for orientation estimation for magnetic, angular rate and gravity (MARG) sensors. In this filter, with employing the quaternion kinematic equation as the process model, we derived a simplified measurement model to create the lightweight system model for Kalman filtering, where the measurement model works efficiently and the involved computation of measurement model is reduced. It’s later proved that the proposed filter saves time consumption. Further, due to that no linearization is involved for the proposed measurement model, the good performance would be guaranteed in theory. For the experiments, a commercial sensor for data collection and an optical system to provide reference measurements of orientation, namely Vicon, are utilized to investigate the performance of the proposed filter. Evaluation for different application scenarios are considered, which primarily includes human motion capture and the drone application. Results indicate that the proposed filter provides reliable performance for both applications. What’s more, the comparison experiment shows that the proposed filter provides better performance in terms of either attitude estimation accu- racy or computational time. </p> </div> </div> </div>

Dynamic analysis of autonomous risk avoidance of amphibious floating bridge based on discrete element method and physical engine

In this paper, based on an intelligent floating bridge, by using discrete element methods and physical engines, under the action of certain missile repulsion fields, the force process and motion path in the process of autonomous evasion of missiles are studied. Firstly, the static simulation of missile repulsion fields is carried out by using the polynomial least square surface fitting method. According to the strength of repulsion field at different times and the extrusion force between the pontoons, the kinematic equation of the pontoon is established. The equation is discretised by using a discrete element method, and the kinematic equation is obtained according to the time iteration. Then, motion analysis is carried out by using a physical engine on the basis of equation Analysis. Finally, the position parameters before and after the self-evasion missile of the floating bridge are calculated, and the simulation program is written in MATLAB. The dynamic simulation experiment of the whole evasion missile process is carried out, and the results are satisfactory.

SIMULATION OF A MULTI-FREQUENCY STOCKBRIDGE VIBRATION DAMPER OSCILATIONS WITH ENERGY SCATTERING HYSTERESIS

Spatial vibrations of a system containing a cable and a mass (solid body of arbitrary spatial configuration) are modeled. The problem is solved in a geometrically linear formulation, taking into account the hysteresis of energy scattering that is based on the kinematic equation. Identification of its parameters is carried out on the basis of experimental data on hysteresis loops of the limit cycle.