Dynamic Simulation of a 12 DoF Biped Robot with Newton-Euler Method using Unit Vector Approach

This paper deals with the optimal kinematic design, dynamic analysis, and application of a 2 degree of freedom (2-DOF) planar parallel mechanism. In the optimal kinematic design phase, the singularities and workspace are investigated, and the optimal kinematic parameters of the mechanism are achieved by minimizing a global and comprehensive conditioning index. The Newton–Euler method is employed to derive the inverse dynamic model. Dynamic simulations show that the inertia force of moving parts is an important factor affecting the dynamic characteristics of the mechanism. The parallel mechanism is incorporated into a 4-DOF hybrid machine tool which also includes a 2-DOF worktable to demonstrate its applicability.

Landing is daunting control design problem because it demands high accuracy and precision by pilot. Among the various states to control for stability and landing in an Aircraft, one is its altitude to handle during landing. Since the linearized model of aircraft is considered and is used for altitude control design. For best tracking performance during glide and flare phase, Integral State feedback Sliding Mode Control (ISSMC) is applied, which is based on unit vector approach. To eliminate error between responded altitude and referenced altitude, a dynamic demand first order filter is used. There has been noted a significant improvement in performance as compared with PID control. When comparing the Integral State feedback Sliding Mode Control with PID during landing phase, the ISSMC yields the best response of glide and flare maneuverability for smooth touch down during landing on runway.

In order to further reduce the incisions of laparoscopic surgery and the possibility of infection, the organic combination of single-incision laparoscopic surgery (SILS) and robotics has made the degree of minimally invasive surgery further improved. A new 5-DOF single-incision laparoscopic surgery robot was designed based on Axiomatic Design Theory, whose structure consisting of the movement mechanism, the endoscope and the position and pose adjustment mechanism. The robot parts are connected in series and parallel, allowing a pivotal motion of the endoscope in the center of the robot for realizing the incision. In order to achieve a performance optimization and a dynamic control of the single-incision laparoscopic surgical robot, the kinematics and dynamic modeling and dynamic stiffness analysis of the robot are especially important. The forward kinematics equation, inverse kinematics equation and Jacobian matrix of the SILS robot are derived based on D-H method and geometric method, and the kinematics numerical simulation is carried out by Matlab. The dynamic equation of the robot is derived by Kane method. Subsequently, a numerical simulation of the robot dynamics equation is performed, with its virtual prototype utilized to set the motion plan of the robot mechanism. After robot’s dynamic simulation, the numerical changes of the driving force and torque for each robot’s moving mechanism are obtained. The performed simulation results further verify the correctness of the established robot’s dynamic model. Finally, utilizing the above methods, the dynamic stiffness model and evaluation index of the robot are determined, and the dynamic stiffness of the robot is analyzed and evaluated. The results of the kinematics, dynamic and stiffness analysis of the SILS robot further validate that the 5-DOF SILS robot has a reasonable structure, motion and sufficient stability to meet the needs of single-incision laparoscopic surgery.

Moment of Inertia Measurement of a CubeSat Through Object Motion Tracking of Trifilar Pendulum Oscillations

In this paper, a new way of computing the constraint transfer matrix for the inverse dynamic and joint force analysis of multibody systems is developed. The method is based on the Newton–Euler method and the screw theory notations. This method is first developed in (Taghvaeipour et al. in Multibody Syst. Dyn. 29(2):139–168, 2013), however, in this study, it is efficiently modified by incorporating a unified constraint transfer matrix for all types of joints. This change makes both the derivation of the equations and the computations less time consuming. Moreover, in the foregoing procedure, the constraint wrenches of a system are obtained in one reference frame, namely, the global reference frame. As a case study, the proposed method is carried out on the agile wrist which is a three-legged spherical parallel robot with three degrees of freedom. At the end, the results obtained by the modified method are verified with the ones calculated by the original procedure and a software package.

The manipulator robots have many applications, such as industrial process, objects translation, process automation, medicine process, etc. Therefore, these kind of robots are studied in many ways. However, most of the reported works use electrical or hydraulic actuators. These actuators have a linear behaviour and the control is easier than pneumatic actuators. The main disadvantages of electrical actuators are the low power-weight rate, the high current related with its load and its weight. The hydraulic actuators are not ecological, needs hydraulic oil which is feedback to the pump. On the other hand, the pneumatic actuators are lighter, faster, having a greater power-weight rate and air feedback is not needed. However, pneumatic actuators are not used into flexible manipulators developing, due to their highly non linear behaviour. In the case of robot dynamic analysis, other researchers have presented the following works. An equations and algorithms are presented in an easy way to understand for all practical robots (Featherstone, 1987), (Featherstone & Orin, 2000), (Khalil & Dombre, 2002). Also, a dynamic simulation is developed to investigate the effects of different profiles into the contact force and the joint torques of a rigid-flexible manipulator (Ata & Johar, 2004). A study of dynamic equations is developed for a robot system holding a rigid object without friction (Gudino-Lau & Arteaga, 2006). Furthermore, a dynamic modeling analysis is developed for parallel robots (Zhaocai & Yueqing, 2008). The link flexibility is considered for system performance and stability. Moreover, an innovative method for simulation is developed (Celentano, 2008) to allow students and researchers, to easily model planar and spatial robots with practical links. However, the reported works are developed using only electrical actuators, not pneumatic actuators. Therefore, this chapter presents how the pneumatic model is used with a two-link flexible robot and its dynamic analysis for the simplified system. Previous researches by the authors include: a simplified thermo-mechanical model for pneumatic actuator has been obtained (Ramos et al., 2006). For animation purposes, the 27

During the morphing process, the dynamic modeling of the morphing wing aircraft presents the characteristics of rigid‐elastic coupling effects, moving boundaries, and low computational efficiency. Meanwhile, parameters such as aerodynamic forces/moments, center of pressure, center of mass, and moment of inertia would also change significantly, which would seriously affect the flight stability. Therefore, this paper mainly focuses on the rigid‐elastic coupling dynamic modeling of morphing wing aircraft. Based on the virtual power principle, a floating coordinate system and the modal synthesis method are adopted to establish a rigid‐elastic coupling dynamic model that accounts for the elasticity of the wings, which can accurately capture the cross‐scale coupling effects between the rigid‐body motion and the elastic deformation of the wings during the continuously morphing process. Considering the moving boundary problem between the fuselage and the wings during the continuously morphing process, a dynamic constraint modeling technique based on the Craig‐Bampton method and a node's life and death technique describing the constraint states are proposed, which can avoid the complex operations of reestablishing the finite element model of the elastic bodies for traditional methods. Moreover, a method of smoothing model for the rigid–elastic coupling system is developed, which can significantly improve the computational efficiency for the dynamic equation of the morphing wing aircraft. And by changing the value of the smoothing factor, preservation of specific high‐frequency components can be controlled. Finally, the numerical examples are carried out to verify the proposed rigid‐elastic coupling dynamic model for the morphing wing aircraft.

In this paper, a robust tracking control problem for underactuated underwater vehicles in horizontal motion is investigated. The presented control scheme that performs the trajectory tracking task is a combination of the backstepping technique and the integral sliding mode control method using the inertial quasi velocities (IQVs) resulting from the inertia matrix decomposition. Unlike many known solutions, the proposed approach allows not only trajectory tracking, but also, due to the fact that IQV includes dynamic and geometric model parameters, allows us to obtain additional information about changes in vehicle behavior during movement. In this way, some insight into its dynamics is obtained. Moreover, the control strategy takes into account model inaccuracies and external disturbances, which makes it more useful from a technical point of view. Another advantage of this work is to indicate problems occurring during the implementation of trajectory tracking in algorithms with a dynamics model containing a diagonal inertia matrix, i.e., without inertial couplings. The theoretical results are illustrated by simulation tests conducted on two models of underwater vehicles with three degrees of freedom (DOF).

Abstract. Research on the vibration characteristics of the mechanical systems is a necessary step for the stable and reliable operation of high-end equipment. The 6 degrees of freedom parallel mechanism is proposed for the supporting mechanism of the antenna. First, the dynamic equations of the moving platform and branch of the mechanism are established. The closed-form dynamics of the mechanism are derived based on the Newton–Euler method. In addition, the vibration equation of the parallel antenna is established based on the vibration theory, and the relationship between the natural frequency, displacement response, and vibration frequency is obtained. Afterward, the pitch and roll poses of a 1.8 m aperture antenna are developed based on a MATLAB software simulation. The actuation forces of parallel antenna under no-load and load conditions are simulated. Finally, the natural frequencies and vibration modes of the initial position and roll (20∘) are simulated based on the Adams software vibration analysis module. Furthermore, the relationship between the displacement response of the moving platform and the resonant frequency is studied based on the harmonic response analysis. The control strategy based on the dynamic model improves the control accuracy of parallel antenna. This research work provides a guarantee for the dynamic characteristics analysis and engineering application of parallel antenna.

Parallel manipulators with less than six degrees of freedom (DOF) have been increasingly used in high-speed hybrid machine tools. The structural features of parallel manipulators are dynamic, a characteristic that is particularly significant when these manipulators are used in high-speed machine tools. However, normal kinematic control method cannot satisfy the requirements of the control system. Many researchers use model-based dynamic control methods, such as the dynamic feedforward control method. However, these methods are rarely used in hybrid machine tools because of the complex dynamic model of the parallel manipulator. In order to study the dynamic control method of parallel manipulators, the dynamic feedforward control method is used in the dynamic control system of a 3-PSP (prismatic-spherical-prismatic) 3-DOF spatial parallel manipulator used as a spindle head in a high-speed hybrid machine tool. Using kinematic analysis as basis and the Newton-Euler method, we derive the dynamic model of the parallel manipulator. Furthermore, a model-based dynamic feedforward control system consisting of both kinematic control and dynamic control subsystems is established. The dynamic control subsystem consists of two modules. One is used to eliminate the influence of the dynamic characteristics of high-speed movement, and the other is used to eliminate the dynamic disturbances in the milling process. Finally, the simulation model of the dynamic feedforward control system of the 3-PSP parallel manipulator is constructed in Matlab/Simulink. The simulations of the control system eliminating the influence of the dynamic characteristics and dynamic disturbances are conducted. A comparative study between the simulations and the normal kinematic control method is also presented.The simulations prove that the dynamic feedforward control method effectively eliminates the influence of the dynamic disturbances and dynamic characteristics of the parallel manipulator on high-speed machine tools, and significantly improves the trajectory accuracy. This is the first attempt to introduce the dynamic feedfordward control method into the 3-PSP spatial parallel manipulator whose dynamic model is complex and provides a study basis for the real-time dynamic control of the high-speed hybrid machine tools.

Flare and relief systems are inherently dynamic process. Relief devices (PSV, rupture disc and flare tips) depend on system pipage for specified performance. These dependencies cause both transitory and lasting impacts. These impacts can only be understood by dynamic analysis. The past 10years of application confirm the need for and credibility of dynamic models. This paper details the theoretical development, validation and utilization experience of flare system dynamic models. INTRODUCTION Steady state flowsheet simulators are fairly routine software in today's processplant design environments. Pipeline transients and control system design are recognized dynamic problems and are best analyzed by simulation. However, dynamic simulation is still infrequently practiced. with cost to benefit ratio rapidly in favor of computerization, applications of dynamic simulations in process industries will undoubtedly multiply into the future. This paper describes a class of design problems in which we saw advantage in applying dynamic simulation oil field flare systems are inherent dynamic processes. Relief devices depend on system pipage for specified performance - relief valve capacity dependent on discharge back pressure, header peak pressure dependent on rupture disc burst conditions, radiation imposed limits dependent on peak relief rate, flare equipment size dependent on relief load characteristics and particulars of the staging philosophy. These dependencies cause both transitory and lasting impacts, e. g. temporal overpressure, flow cycling, and flame out events. And these impacts can only be understood by dynamic analysis. The past 10years of application confirm the need for dynamic models and the credibility of this technology improved in close association with better understanding of the complex flare system interactions. FLARE SYSTEM DESIGN CONSIDERATIONS Flare systems are final safeguards against overpressure, during plant transient conditions. The flare system must be designed to relieve excessive pressure to insure safety, specifically not to exceed levels allowed by "Code". API Design Practice 520 & 521 are widely observed as voluntary guidelines on the design and operation of flare systems in the American Petroleum Industry. Two key concepts are particularly applicable to this work. "Pressure relieving devices are installed to ensure that a process system or any of its components are not subject to pressures that exceed the Maximum Allowable Accumulated Pressure." "Fail safe device and automatic equipment should not replace pressure relieving devices as protection for individual process equipment." The first paragraph specifies the requirement of relief devices in the protection of equipment against overpressure. The second paragraph further stipulates that pressure relieving devices cannot be replaced nor substituted. This second paragraph therefore excludes all but pressure relieving devices in flare systems. API (ASME) pressure relieving devices for flare systems are clearly defined as PSV (Pressure Safety Valve), rupture disc and flare tip. ASME section VIII, Div. 1 Code stipulates the pressure relief requirements on unfired pressure vessels.

Aiming at the issue of inaccurate design of multistage spiral pair structures due to the inaccuracy of the traditional transmission efficiency calculation formula for double-screw swinging hydraulic cylinders, which are used in steering gear, a new transmission efficiency calculation formula for these cylinders is proposed through mathematical modeling and dynamic analysis. Corresponding flexible dynamic and rigid dynamic simulation models of the double-screw swinging hydraulic cylinder are established to investigate the output characteristics, load startup characteristics, and maximum torque of the spiral pair. The accuracy of the flexible dynamic model and the rigid dynamic model is compared, and an experimental validation is conducted using a hydraulic test bench. The following conclusions are drawn: the calculation accuracy of the new transmission efficiency formula is improved by 21% compared to the traditional formula; under rated load pressure, the output torque accuracy of the flexible dynamic simulation model is improved by 55%. The flexible dynamic simulation model's closer alignment with experimental results proves its necessity. The research offers new simulation tools and a theoretical basis for the development of high-precision efficiency prediction models, holistic design, and optimization of double-helical oscillating hydraulic cylinders for underwater equipment.

This paper discusses dynamic modeling and simulation of distributed static compensators (DSTATCOM) in system impact studies involving renewable applications, e.g., wind or solar power plants. Two dynamic simulation models of the DTSTACOM are presented and discussed. Dynamic simulations are presented to show that a reactive compensation system (RCS) assembled with the DSTATCOM as a master controller complies with reactive power, voltage control, and low voltage ride-though requirements for a wind power plant. Benchmark and real system models integrate the mechanically switched capacitors and the wind turbine generator reactive power capability into the total RCS system. The reactive characteristics of the DSTATCOM are also discussed.

In this paper, a 5-DOF serial-parallel manipulator with RP-(2-RRU/1-RUU) structure is proposed. This manipulator is used to the automatic production line, to complete the materials' loading, delivery and unloading. In order to ensure the safety and high efficiency production, the manipulator has good stiffness and high accuracy, and is suitable for the fast operation. Based on the above requirements, the manipulator has the big work space characteristic of the serial mechanism and the high precision and stiffness characteristic of the parallel mechanism. However, the difficulty of its dynamics analysis is increasing. In this paper, the modal analysis and the harmonic response analysis are carried out using finite element analysis software, and the dynamic characteristics of the manipulator are derived. The inverse dynamics modeling has been performed based on the Newton-Euler method. The dynamics simulation is carried out to check the correctness of dynamics modeling. This study is also significant to the trajectory planning and control system.

The stability analysis of articulated frame steer vehicle models is presented. To reveal the relationship between the “oversteer” and “jack-knife” motion modes based on a 2 degree of freedom (DOF) and 3 DOF vehicle models, respectively, the results derived from these models are investigated and compared. To identify the effects of design variables on the lateral stability of the vehicle, a more realistic model with a hydraulic rotary valve and dynamic tyre models is generated on the basis of the 3 DOF model and the results derived from these models are examined and compared. Similar to traditional articulated vehicles, the jack-knife and ‰snaking” modes were identified from practical operations of the articulated frame steer vehicles. Results demonstrate that, with the decrease of the angular spring (representing the hydraulic cylinder between the front and rear sections of the vehicle) stiffness coefficient, the oversteer mode evolves into the jack-knife mode. Compared with the static tyre model, the effects of dynamic transient lateral tyre force degrades the stability of the vehicle over the lower speed range. Results also illustrate that, with the fluid leakage either in the rotary valve or in the hydraulic cylinder, the stability of the oversteer mode dominated motion degrades. On the contrary, in the case of snaking mode dominated motion, the introduction of the fluid leakage will improve the stability of the vehicles.