Stability-Guaranteed Anti-Sway Controller Design for a Redundant Articulated Hydraulic Manipulator in the Vertical Plane

2017 ◽  
Author(s):  
Pauli Mustalahti ◽  
Janne Koivumäki ◽  
Jouni Mattila
Keyword(s):  
Degrees Of Freedom ◽  
Controller Design ◽  
Vertical Plane ◽  
Plane Motion ◽  
Nonlinear Controller ◽  
Hydraulic Manipulators ◽  
Revolute Joints ◽  
Subsystem Level ◽  
Heavy Loads ◽  
Rotating Load

Articulated hydraulic manipulators are widely used for moving heavy loads. Commercial manipulators are most often equipped with a rotating load-grasping tool connected at the end of the manipulator via a pair of passive (unactuated) revolute joints. In free-space motion, these passive joints are subject to swaying motions due to the manipulator tip accelerations. Because these passive joints are not directly controllable due to their passive nature, a skilled driver is needed to compensate for the load swaying. In this paper, we extend the nonlinear model-based Virtual Decomposition Control (VDC) theory to cover anti-sway control of underactuated multiple degrees-of-freedom (DOF) hydraulic redundant manipulators. The proposed nonlinear controller performs the control design and stability analysis of the hydraulic robotic manipulator at the subsystem level. Experiments are conducted in a full-scale loader manipulator to verify that the proposed controller can efficiently damp the load swaying in a case study of redundant vertical plane motion.

scholarly journals Controller Design for the Rotational Dynamics of a Quadcopter

2019 ◽  
Vol 38 (2) ◽  
pp. 269-274
Author(s):  
Rabia Rashdi ◽  
Zeeshan Ali ◽  
Javed Rahman Larik ◽  
Liaquat Ali Jamro ◽  
Urooj Baig
Keyword(s):  
Mathematical Model ◽  
Degrees Of Freedom ◽  
Controller Design ◽  
Sliding Mode ◽  
Mechanical Systems ◽  
Euler Method ◽  
State Variables ◽  
Nonlinear Controller ◽  
Nonlinear Dynamic Model ◽  
Highly Nonlinear

Researchers have shown their interests in establishing miniature flying robots to be utilized for, both, commercial and research applications. This is due to that fact that there appears to be a huge advancement in miniature actuators and sensors which depend on the MEMS (Micro Electro-Mechanical Systems) NEMS (Nano-Electro Mechanical Systems). This research underlines a detailed mathematical model and controller design for a quadcopter. The nonlinear dynamic model of the quadcopter is derived from the Newton-Euler method and Euler Lagrange method. The motion of a quadcopter can be classified into two subsystems: a rotational subsystem (attitude and heading) and translational subsystem (altitude and x and y motion). The rotational system is fully actuated whereas translational subsystem is under actuated. However, a quadcopter is 6 DOF (Degrees of Freedom) under actuated system. The controller design of a quadcopter is difficult due to its complex and highly nonlinear mathematical model where the state variables are strongly coupled and contain under actuated property. Nonlinear controller such as SMC (Sliding Mode Controller) is used to control altitude, yaw, pitch, and roll angles.Simulation results show that the robustness of the SMC design gives a better way to design a controller with autonomous stability flight with good tracking performance and improved accuracy without any chattering effect. The system states are following the desired trajectory as expected.

Nonlinear Model-Based Controller Design for a Hydraulic Rack and Pinion Gear Actuator

2018 ◽  
Author(s):  
Pauli Mustalahti ◽  
Jouni Mattila
Keyword(s):  
Closed Loop ◽  
Controller Design ◽  
Dynamical Behavior ◽  
Control Design ◽  
Closed Loop Control ◽  
Loop Control ◽  
Hydraulic Manipulators ◽  
Pinion Gear ◽  
Hydraulic Manipulator ◽  
Heavy Loads

Hydraulic manipulators are extensively utilized to move heavy loads in many industrial tasks. In commercial applications, a manipulator base is required to rotate a motion range of the full 360°. This is usually implemented by using a hydraulic rack and pinion gear actuator. Due to the manipulator’s long reach and heavy loads, manipulator tip acceleration can produce significant torque to the rotation gear in free-space motion. Imposed by nonlinear dynamical behavior (involving, e.g., the gear backlash and actuator friction) added to high inertia, a system closed-loop control design becomes a challenging task. An advanced closed-loop control enables to increase the automation-level of hydraulic manipulators. This study designs a novel subsystem-dynamics-based controller for a hydraulic rack and pinion gear actuator utilizing the control design principles of the virtual decomposition control (VDC) approach. An adaptive backlash compensation is incorporated in the control design. Furthermore, the proposed controller is implemented in previously-designed state-of-the-art hydraulic manipulator control. The stability of the overall control design is proven. Experiments with a full-scale commercial hydraulic manipulator demonstrate the effectiveness of the proposed adaptive backlash compensation and the overall control performance.

scholarly journals Adaptive Digital Disturbance Rejection Controller Design for Underwater Thermal Vehicles

2021 ◽  
Vol 9 (4) ◽  
pp. 406
Author(s):  
Guohui Wang ◽  
Yanan Yang ◽  
Shuxin Wang
Keyword(s):  
Disturbance Rejection ◽  
Control Method ◽  
Controller Design ◽  
Least Squares Method ◽  
Vertical Plane ◽  
Estimation Method ◽  
Plane Motion ◽  
External Disturbances ◽  
Control Approach ◽  
Waves And Currents

Underwater thermal vehicles, as ocean observation tools, are frequently affected by environment disturbances such as waves and currents, which may cause degradation of the observation accuracy of the vehicles. Consequently, it is important to design a controller for a vehicle that can resist ocean disturbance. In this study, an underwater thermal vehicle principle is introduced, and the mathematical model is established in the vertical plane motion. On this basis, an adaptive digital disturbance suppression control method is proposed. For known disturbance parameters, this controller could compensate for external disturbances by pre-setting control parameters using the internal model principle and parameterizations method. For the case where the disturbance parameters are unknown, disturbance parameter estimation method based on forgetting factor least-squares method is proposed to transform the unknown parameter disturbance into a disturbance with known parameters, which is then suppressed by the adaptive digital disturbance rejection control approach. This solution could effectively solve the challenges caused by parameter uncertainty and unknown time-varying ocean external disturbances. Finally, simulations are carried out for the Petrel underwater thermal glider as an example. The simulation results show the proposed control method’s superiority and inherent robustness.

scholarly journals Biologically Inspired Design and Development of a Variable Stiffness Powered Ankle-Foot Prosthesis

2019 ◽  
Vol 11 (4) ◽  
Author(s):  
Alexander Agboola-Dobson ◽  
Guowu Wei ◽  
Lei Ren
Keyword(s):  
Lower Limb ◽  
Degrees Of Freedom ◽  
Sagittal Plane ◽  
Frontal Plane ◽  
Variable Stiffness ◽  
Plane Motion ◽  
Biologically Inspired ◽  
Passive Rotation ◽  
Ground Conditions ◽  
Biologically Inspired Design

Recent advancements in powered lower limb prostheses have appeased several difficulties faced by lower limb amputees by using a series-elastic actuator (SEA) to provide powered sagittal plane flexion. Unfortunately, these devices are currently unable to provide both powered sagittal plane flexion and two degrees of freedom (2-DOF) at the ankle, removing the ankle’s capacity to invert/evert, thus severely limiting terrain adaption capabilities and user comfort. The developed 2-DOF ankle system in this paper allows both powered flexion in the sagittal plane and passive rotation in the frontal plane; an SEA emulates the biomechanics of the gastrocnemius and Achilles tendon for flexion while a novel universal-joint system provides the 2-DOF. Several studies were undertaken to thoroughly characterize the capabilities of the device. Under both level- and sloped-ground conditions, ankle torque and kinematic data were obtained by using force-plates and a motion capture system. The device was found to be fully capable of providing powered sagittal plane motion and torque very close to that of a biological ankle while simultaneously being able to adapt to sloped terrain by undergoing frontal plane motion, thus providing 2-DOF at the ankle. These findings demonstrate that the device presented in this paper poses radical improvements to powered prosthetic ankle-foot device (PAFD) design.

Experimental evaluation of time-varying impulse shaping with a two-link flexible manipulator

Robotica ◽  
1996 ◽  
Vol 14 (3) ◽  
pp. 339-345 ◽  
Author(s):  
Jung-Keun Cho ◽  
Youn-Sik Park
Keyword(s):  
Vibration Reduction ◽  
Vertical Plane ◽  
Joint Stiffness ◽  
Flexible Manipulator ◽  
Input Shaping ◽  
Time Varying ◽  
Modal Properties ◽  
Revolute Joints ◽  
Point Motion ◽  
Point To Point

SUMMARYIn the authors' previous paper,10 an input shaping method was presented to reduce motion-induced vibrations effectively for various classes of flexible systems. In this paper, the effectiveness of the shaping method is experimentally demonstrated with a two-link flexible manipulator systemThe manipulator for experiments includes two revolute joints and two flexible links, and moves on a vertical plane under gravity. An analytic model is developed considering the flexibility of the system and its joint stiffness in order to derive an appropriate estimation of dynamic modal properties. The input shaping method used in this work utilizes time-varying modal properties obtained from the model instead of the conventional input shaping method which employs time-invariant modal properties. A point-to-point motion is tested in order to show the effectivess of the proposed shaping method in vibration reduction during and after a given motion. The given reference trajectories are shaped to suppress the motion induced vibration. The test results demonstrate that the link vibration can be greatly suppressed during and after a motion, and the residual vibration reduction was observed more than 90% by employing this time-varying impulse shaping technique.

Sign in / Sign up

Export Citation Format

Share Document