scholarly journals Novel Concept for Electro-Hydrostatic Actuators for Motion Control of Hydraulic Manipulators

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6566
Author(s):  
Konrad Johan Jensen ◽  
Morten Kjeld Ebbesen ◽  
Michael Rygaard Hansen
Keyword(s):  
Motion Control ◽  
Hydraulic Manipulators ◽  
Path Control ◽  
Differential Flow ◽  
Hydraulic Cylinders ◽  
Hydraulic Crane ◽  
Flow Compensation ◽  
Novel Concept ◽  
Four Quadrant ◽  
Similar Dynamic

Self-contained hydraulic cylinders have gained popularity in the recent years but have not been implemented for high power articulated hydraulic manipulators. This paper presents a novel concept for an electro-hydrostatic actuator applicable to large hydraulic manipulators. The actuator is designed and analyzed to comply with requirements such as load holding, overload handling, and differential flow compensation. The system is analyzed during four quadrant operation to investigate energy efficiency and regenerative capabilities. Numerical simulation is carried out using path control and 2DOF anti-swing of a hydraulic crane as a load case to illustrate a real world scenario. A comparison with traditional valve-controlled actuators is conducted, showing significantly improved efficiency and with similar dynamic response, as well as the possibility for regenerating energy.

Stable and High Performance Energy-Efficient Motion Control of Electric Load Sensing Controlled Hydraulic Manipulators

2013 ◽  
Author(s):  
Janne Koivumäki ◽  
Jouni Mattila
Keyword(s):  
Motion Control ◽  
Energy Efficient ◽  
High Performance ◽  
System Stability ◽  
Electric Load ◽  
Hydraulic Systems ◽  
Control Approach ◽  
Load Sensing ◽  
Hydraulic Manipulators ◽  
Control Scheme

In order to achieve higher energy efficiency for hydraulic systems the Load Sensing (LS) systems, i.e. a Variable Displacement Pump (VDP) with hydro-mechanical control system, can be considered as a state-of-the-art solution. However, as is well known, these traditional hydraulic LS-systems are usually characterized by difficulties in tuning, which can lead to system stability problems. In our previous studies, we have developed a high precision motion control for hydraulic manipulators with separate meter-in meter-out controlled hydraulic actuators. Our control approach was based on the Virtual Decomposition Control (VDC) approach that ensured high motion tracking performance while rigorously guaranteeing the system stability. In this paper, we propose both energy-efficient and high performance nonlinear model based motion control scheme that utilizes the developed servocontrolled Electric Load Sensing (ELS) system for hydraulic robotic manipulators. Experimental results are presented with the proposed ELS-controlled VDP and hydraulic manipulator lifting servoactuator that utilized a separate meter-in meter-out flow control scheme.

scholarly journals Development of a redundant anthropomorphic hydraulically actuated manipulator with a roll-pitch-yaw spherical wrist

2021 ◽  
Author(s):  
Min Cheng ◽  
Zenan Han ◽  
Ruqi Ding ◽  
Junhui Zhang ◽  
Bing Xu
Keyword(s):  
Inverse Kinematic ◽  
Parallel Structure ◽  
Test Results ◽  
Hydraulic Manipulators ◽  
Hydraulically Actuated ◽  
Physical Prototype ◽  
Spherical Wrist ◽  
Hydraulic Cylinders ◽  
Self Motion ◽  
Kinematic Solution

AbstractThe demand for redundant hydraulic manipulators that can implement complex heavy-duty tasks in unstructured areas is increasing; however, current manipulator layouts that remarkably differ from human arms make intuitive kinematic operation challenging to achieve. This study proposes a seven-degree-of-freedom (7-DOF) redundant anthropomorphic hydraulically actuated manipulator with a novel roll-pitch-yaw spherical wrist. A hybrid series-parallel mechanism is presented to achieve the spherical wrist design, which consists of two parallel linear hydraulic cylinders to drive the yaw/pitch 2-DOF wrist plate connected serially to the roll structure. Designed as a 1RPRRR-1SPU mechanism (“R”, “P”, “S”, and “U” denote revolute, prismatic, spherical, and universal joints, respectively; the underlined letter indicates the active joint), the 2-DOF parallel structure is partially decoupled to obtain simple forward/inverse kinematic solutions in which a closed-loop subchain “RPRR” is included. The 7-DOF manipulator is then designed, and its third joint axis goes through the spherical center to obtain closed-form inverse kinematic computation. The analytical inverse kinematic solution is drawn by constructing self-motion manifolds. Finally, a physical prototype is developed, and the kinematic analysis is validated via numerical simulation and test results.

Automated Feed-Forward Learning for Pressure-Compensated Mobile Hydraulic Valves With Significant Dead-Zone

2017 ◽  
Author(s):  
Jarmo Nurmi ◽  
Jouni Mattila
Keyword(s):  
Motion Control ◽  
Dead Zone ◽  
Heavy Duty ◽  
Automated Identification ◽  
Forward Models ◽  
Feed Forward ◽  
Loop Control ◽  
Hydraulic Manipulators ◽  
Hydraulic Manipulator ◽  
Hydraulic Valves

Hydraulic manipulators on mobile machines, whose hydraulic actuators are usually controlled by mobile hydraulic valves, are being considered for robotic closed-loop control. A feed-forward-based strategy combining position and velocity feedback has been found to be an effective method for the motion control of pressure-compensated mobile hydraulic valves that have a significant dead zone. The feed-forward can be manually identified. However, manually identifying the feed-forward models for each valve-actuator pair is often very time-consuming and error-prone. For this practical reason, we propose an automated feed-forward learning method based on velocity and position feedback. We present experimental results for a heavy-duty hydraulic manipulator on a forest forwarder to demonstrate the effectiveness of the proposed method. These results motivate the automated identification of velocity feed-forward models for motion control of heavy-duty hydraulic manipulators controlled by pressure-compensated mobile hydraulic valves that have a significant input dead zone.

scholarly journals Valve Deadzone/Backlash Compensation for Lifting Motion Control of Hydraulic Manipulators

Machines ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 57
Author(s):  
Lan Li ◽  
Ziying Lin ◽  
Yi Jiang ◽  
Cungui Yu ◽  
Jianyong Yao
Keyword(s):  
Motion Control ◽  
High Precision ◽  
Control Method ◽  
Flow Characteristics ◽  
Friction Model ◽  
Adaptive Robust Control ◽  
Hydraulic Manipulators ◽  
System A ◽  
Lugre Friction Model ◽  
Control Scheme

In this paper, a novel nonlinear model and high-precision lifting motion control method of a hydraulic manipulator driven by a proportional valve are presented, with consideration of severe system nonlinearities, various uncertainties as well as valve backlash/deadzone input nonlinearities. To accomplish this mission, based on the independent valve orifice throttling process, a new comprehensive pressure-flow model is proposed to uniformly indicate both the backlash and deadzone effects on the flow characteristics. Furthermore, in the manipulator lifting dynamics, considering mechanism nonlinearity and utilizing a smooth LuGre friction model to describe the friction dynamics, a nonlinear state-space mathematical model of hydraulic manipulation system is then established. To suppress the adverse effects of severe nonlinearities and uncertainties in the system, a high precision adaptive robust control method is proposed via backstepping, in which a projection-type adaptive law in combination with a robust feedback term is conducted to attenuate various uncertainties and disturbances. Lyapunov stability analysis demonstrates that the proposed control scheme can acquire transient and steady-state close-loop stability, and the excellent tracking performance of the designed control law is verified by comparative simulation results.

Nonlinear Robust Path Control for a Field Robot Scouting in Strawberry Orchards

2017 ◽  
Author(s):  
Douglas Freese ◽  
Yunjun Xu
Keyword(s):  
Motion Control ◽  
Autonomous Robots ◽  
Labor Cost ◽  
Agricultural Products ◽  
Control Methods ◽  
Path Control ◽  
Seasonal Agricultural Workers ◽  
And Control ◽  
Vision Feedback ◽  
Nonlinear Robust

In recent years, the interests of introducing autonomous robots by growers into agriculture fields are rejuvenated due to the ever-increasing labor cost and the recent declining numbers of seasonal agricultural workers. Among all the enabling technologies used in robot operations for agricultural products with shallow structures, controlling a robot to traverse throughout a field is challenging. In this study the motion control of a robot, custom-designed for strawberry fields, is separated into multiple phases to deal with the over-bed and cross-bed operation needs. Different sensors are used for different control phases. In particular, nonlinear robust controllers are designed for the cross-bed motion, purely relying on vision feedback. The proposed sensing and control methods are successfully validated in a commercial farm.

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