scholarly journals Impedance Control Considering Velocity Saturation of a Series Elasticity System with a Motor

2021 ◽  
Vol 33 (4) ◽  
pp. 833-842
Author(s):  
Ren Fukui ◽  
Yasuhito Kusakabe ◽  
Ryojun Ikeura ◽  
Soichiro Hayakawa ◽  
◽  
...  
Keyword(s):  
Impedance Control ◽  
Conventional System ◽  
Series Elasticity ◽  
Velocity Saturation ◽  
Elasticity System ◽  
Impedance Characteristics ◽  
Simulation And Experiment ◽  
The Stability ◽  
Torsion Bar ◽  
Compact Mechanism

Human-machine cooperative robots are required to drive their arms with low impedance and high torque. As a compact mechanism that generates a large torque and has low impedance characteristics, the series elastic drive system, in which an elastic element is inserted between the motor and driving unit, has been proposed. In this paper, we propose a method of applying impedance control to a series elasticity system with a torque-compensating motor that uses a torsion bar as an elastic body that enables its use under high loads. The stability of the system was verified via simulation and experiment by considering the allowable speed and maximum torque of the motor. The experimental results from the conventional system and the proposed system were compared. The proposed system was confirmed to be superior to the conventional system in terms of both stability and tracking performance. Consequently, the effectiveness of our proposed system was confirmed.

scholarly journals Null-space impedance control of 7-degree-of-freedom redundant manipulators based on the arm angles

2020 ◽  
Vol 17 (3) ◽  
pp. 172988142092529
Author(s):  
Genliang Xiong ◽  
Yang Zhou ◽  
Jiankang Yao
Keyword(s):  
Control Method ◽  
Null Space ◽  
Impedance Control ◽  
High Gain ◽  
Degree Of Freedom ◽  
Redundant Manipulators ◽  
Redundant Manipulator ◽  
Impedance Characteristics ◽  
The Stability ◽  
Self Motion

An impedance control method in null-space for 7-degree-of-freedom redundant manipulators is presented in this article. The null-space impedance motion of the redundant manipulator was described in the angle domain and a null-space impedance equation was established. To successfully obtain joint angular velocity, a high-gain observer is designed. The stability of the proposed control method was proved based on passive theory. The proposed null-space impedance control method not only preserved the Cartesian space impedance characteristics of the redundant manipulator but also achieved null-space impedance control. When the manipulator interacted with the outside world, the position error of the end effector asymptotically converged due to the self-motion of the manipulator. Simulations and experiments of the general impedance control method and the proposed impedance control method verified the effectiveness of the proposed method.

scholarly journals Stability-Guaranteed and High Terrain Adaptability Static Gait for Quadruped Robots

Sensors ◽  
2020 ◽  
Vol 20 (17) ◽  
pp. 4911
Author(s):  
Qian Hao ◽  
Zhaoba Wang ◽  
Junzheng Wang ◽  
Guangrong Chen
Keyword(s):  
Impedance Control ◽  
Stability Margin ◽  
Planning Method ◽  
Legged Robots ◽  
Gait Planning ◽  
Quadruped Locomotion ◽  
Quadruped Robots ◽  
Adjustment Strategy ◽  
Compliant Behavior ◽  
The Stability

Stability is a prerequisite for legged robots to execute tasks and traverse rough terrains. To guarantee the stability of quadruped locomotion and improve the terrain adaptability of quadruped robots, a stability-guaranteed and high terrain adaptability static gait for quadruped robots is addressed. Firstly, three chosen stability-guaranteed static gaits: intermittent gait 1&2 and coordinated gait are investigated. In addition, then the static gait: intermittent gait 1, which is with the biggest stability margin, is chosen to do a further research about quadruped robots walking on rough terrains. Secondly, a position/force based impedance control is employed to achieve a compliant behavior of quadruped robots on rough terrains. Thirdly, an exploratory gait planning method on uneven terrains with touch sensing and an attitude-position adjustment strategy with terrain estimation are proposed to improve the terrain adaptability of quadruped robots. Finally, the proposed methods are validated by simulations.

Control System Design of Upper Limb Rehabilitation Robot

2013 ◽  
Vol 310 ◽  
pp. 477-480 ◽  
Author(s):  
Gang Yu ◽  
Jin Wu Qian ◽  
Lin Yong Shen ◽  
Ya Nan Zhang
Keyword(s):  
Control System ◽  
Upper Limb ◽  
Impedance Control ◽  
Medical Personnel ◽  
Rehabilitation Robot ◽  
Upper Limb Rehabilitation ◽  
Rehabilitation Training ◽  
Simulation And Experiment ◽  
Limb Rehabilitation ◽  
Active Training

In traditional iatrical method, the patients with hemiplegia were assisted mainly by medical personnel to complete rehabilitation training. To make the medical personnel work easily and improve the effect of rehabilitation training, the rehabilitation robot was adopted. And the control system of a four DOF upper limb rehabilitation robot was designed based on impedance control to assist the patients with hemiplegia to complete rehabilitation training after the kinematic and kinetic analysis was finished. Then finished the analysis, simulation, and experiment of monarticular movement and multiarticulate movement after the analyzing the algorithm to tested the control system. The control system based on impedance control of the upper limb rehabilitation robot can realize the passive training which followed the planning trajectory, and active training which followed patients’ awareness of movement.

Robust Impedance Control of Manipulators Carrying a Heavy Payload

2010 ◽  
Vol 132 (5) ◽  
Author(s):  
Farhad Aghili
Keyword(s):  
Force Measurement ◽  
Impedance Control ◽  
Stability And Convergence ◽  
Robot Dynamics ◽  
Control Input ◽  
Heavy Load ◽  
Impedance Model ◽  
Force Moment ◽  
Loop Feedback ◽  
The Stability

A heavy payload attached to the wrist force/moment (F/M) sensor of a manipulator can cause the conventional impedance controller to fail in establishing the desired impedance due to the noncontact components of the force measurement, i.e., the inertial and gravitational forces of the payload. This paper proposes an impedance control scheme for such a manipulator to accurately shape its force-response without needing any acceleration measurement. Therefore, no wrist accelerometer or a dynamic estimator for compensating the inertial load forces is required. The impedance controller is further developed using an inner/outer loop feedback approach that not only overcomes the robot dynamics uncertainty, but also allows the specification of the target impedance model in a general form, e.g., a nonlinear model. The stability and convergence of the impedance controller are analytically investigated, and the results show that the control input remains bounded provided that the desired inertia is selected to be different from the payload inertia. Experimental results demonstrate that the proposed impedance controller is able to accurately shape the impedance of a manipulator carrying a relatively heavy load according to the desired impedance model.

A Parametric Absorber for Friction-Induced Vibrations

2003 ◽  
Author(s):  
Horst Ecker
Keyword(s):  
Numerical Methods ◽  
Harmonic Function ◽  
Stability Limit ◽  
Conventional System ◽  
Mass System ◽  
Main Mass ◽  
System A ◽  
Excited System ◽  
Excitation Force ◽  
The Stability

This contribution deals with the suppression of friction-induced vibrations of a mechanical system. A two-mass system is considered, with the main mass excited by a friction-generated self-excitation force and a smaller second mass attached to the main mass. The parameter of the connecting stiffness between the main mass and the absorber mass is a harmonic function of time and represents a parametric excitation. The purpose of the second mass is to act as a “parametric absorber” and to cancel vibrations. Critical values for the damping parameters of the conventional system are calculated, where the system operates on the stability limit. Analytical and numerical methods are employed to determine the stability of the parameter-excited system. A study for selected parameters shows within which limits friction-induced vibrations can be suppressed effectively by a parametric absorber.

scholarly journals Online MTPA Trajectory Tracking of IPMSM Based on a Novel Torque Control Strategy

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3261 ◽  
Author(s):  
Jianxia Sun ◽  
Cheng Lin ◽  
Jilei Xing ◽  
Xiongwei Jiang
Keyword(s):  
Trajectory Tracking ◽  
Control Strategy ◽  
Torque Control ◽  
Current Reference ◽  
Torque Control Strategy ◽  
Unit Model ◽  
Interior Permanent Magnet ◽  
Simulation And Experiment ◽  
The Stability ◽  
Maximum Torque Per Ampere

The maximum-torque-per-ampere (MTPA) scheme is widely used in the interior permanent magnet synchronous machine (IPMSM) drive system to reduce copper losses. However, MTPA trajectory is complicated to solve analytically. In order to realize online MTPA trajectory tracking, this paper proposes a novel torque control strategy. The torque control is designed to be closed form. Considering the machine reluctance torque as the torque feedback, when this is compared with the torque reference, then the excitation torque reference can be obtained. Since the excitation torque is proportional to the q-axis current, the q-axis current reference can be fed by the excitation torque reference through a proportional regulator. Once the q-axis current reference is given, the d-axis current reference can be calculated based on the per-unit model, which aims to simplify the calculation and make the control strategy independent of machine parameters. In this paper, the stability of the control system is demonstrated. Meanwhile, simulation and experiment results show this torque control strategy can realize MTPA trajectory tracking online and have success in transients.

Research of Velocity Stability of Separate Meter in and Separate Meter out Control System for Over-Running Load

2015 ◽  
Vol 727-728 ◽  
pp. 752-756
Author(s):  
Zhong Yi Cao ◽  
Xin Ming Liu ◽  
Wan Rong Wu
Keyword(s):  
Control System ◽  
Simulation Model ◽  
Hydraulic System ◽  
The Novel ◽  
Velocity Control ◽  
Factors Affecting ◽  
Simulation And Experiment ◽  
The Stability

There are some defects in the traditional over-running load hydraulic system, such as velocity control is poor and prone to velocity jitter, etc. In order to improve these weaknesses, the components and work principle of the separate meter in and separate meter out (SMISMO) were introduced and the actuator’s feature were analyzed , the simulation model of hydraulic studied system was built, the factors affecting the stability of the system are discussed in this paper. Simulation and experiment showed that the novel control system possessed higher velocity control precise and good stable characteristics.

Impedance Control of Gyroscopic Power Generator

2011 ◽  
Author(s):  
Tomoyuki Takahashi ◽  
Jun Iwasaki ◽  
Hiroshi Hosaka
Keyword(s):  
Steady State ◽  
Phase Difference ◽  
High Speed ◽  
Control Method ◽  
Impedance Control ◽  
Low Frequency ◽  
Power Generator ◽  
Communication Devices ◽  
High Speed Rotation ◽  
The Stability

The gyroscopic power generator produces a high-speed rotation of magnets from low-frequency vibrations and supplies electric power to information and communication devices that use human vibrations in daily life. In this paper, in order to increase the stability and the output power of the generator, a simple equation that indicates the steady state approximate solution of the phase difference is derived. From the derived solution, a control method for the steady state is verified by the simulations. In order to maintain the stability and high power generation for variable input vibrations, the impedance control method using the phase difference is developed and verified experimentally.

Impedance Control of Manipulators With Heavy Payload for Spacecraft Rendezvous and Docking Simulators

2009 ◽  
Author(s):  
Farhad Aghili
Keyword(s):  
Sensitivity Analysis ◽  
Rigid Body ◽  
Impedance Control ◽  
Sensor Noise ◽  
Combined System ◽  
Laboratory Environment ◽  
Force Moment ◽  
Applied Forces ◽  
The Stability ◽  
Rendezvous And Docking

This paper presents a method to control a manipulator system grasping a rigid-body payload so that the motion of the combined system in consequence of external applied forces to be the same as another free-floating rigid-body (with different inertial properties). This allows zero-g emulation of a scaled spacecraft prototype under the test in a 1-g laboratory environment. The controller consisting of motion feedback and force/moment feedback adjusts the motion of the test spacecraft so as to match that of the flight spacecraft. The stability of the overall system is analytically investigated, and the results show that the system remains stable provided that the inertial properties of two spacecraft are different and that an upperbound on the norm of the inertia ratio of the payload to manipulator is respected. Important practical issues such as calibration and sensitivity analysis to sensor noise and quantization are also presented. Finally, experimental results are presented.

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