Impedance Control of Space Robots Using Passive Degrees of Freedom in Controller Domain

2005 ◽  
Vol 127 (4) ◽  
pp. 564-578 ◽  
Author(s):  
Pushpraj Mani Pathak ◽  
Amalendu Mukherjee ◽  
Anirvan Dasgupta
Keyword(s):  
Force Control ◽  
Degrees Of Freedom ◽  
Impedance Control ◽  
Space Structure ◽  
Degree Of Freedom ◽  
Robotic Systems ◽  
Stable Method ◽  
Space Robots ◽  
End Effector ◽  
Control Schemes

Impedance control is an efficient and stable method of providing trajectory and force control in robotic systems. The procedure by which the impedance of the manipulator is changed is a very important aspect in the design of impedance based control schemes. In this work, a scheme is presented in which the control of impedance at the interface of the end effector and the space structure is achieved by introduction of a passive degree of freedom (DOF) in the controller of the robotic system. The impedance is shown to depend upon a compensation gain for the dynamics of the passive DOF. To illustrate the methodology, an example of a two DOF planer space robot is considered.

scholarly journals Smart and Modular

2011 ◽  
Vol 133 (09) ◽  
pp. 48-51
Author(s):  
Harry H. Cheng ◽  
Graham Ryland ◽  
David Ko ◽  
Kevin Gucwa ◽  
Stephen Nestinger
Keyword(s):  
Degrees Of Freedom ◽  
Robotic System ◽  
Search And Rescue ◽  
Degree Of Freedom ◽  
Robotic Systems ◽  
Modular Robots ◽  
Modular Robot ◽  
Modular Systems ◽  
The Past ◽  
Three Degrees Of Freedom

This article discusses the advantages of a modular robot that can reassemble itself for different tasks. Modular robots are composed of multiple, linked modules. Although individual modules can move on their own, the greatest advantage of modular systems is their structural reconfigurability. Modules can be combined and assembled to form configurations for specific tasks and then reassembled to suit other tasks. Modular robotic systems are also very well suited for dynamic and unpredictable application areas such as search and rescue operations. Modular robots can be reconfigured to suit various situations. Quite a number of modular robotic system prototypes have been developed and studied in the past, each containing unique geometries and capabilities. In some systems, a module only has one degree of freedom. In order to exhibit practical functionality, multiple interconnected modules are required. Other modular robotic systems use more complicated modules with two or three degrees of freedom. However, in most of these systems, a single module is incapable of certain fundamental locomotive behaviors, such as turning.

Hybrid Position/Force Control for a RRR 3-DoF Manipulator

2011 ◽  
Vol 48-49 ◽  
pp. 589-592 ◽  
Author(s):  
Shi Xiang Tian ◽  
Sheng Ze Wang
Keyword(s):  
Force Control ◽  
Free Space ◽  
High Performance ◽  
Degree Of Freedom ◽  
End Effector ◽  
Robot Trajectory ◽  
Simulation Results ◽  
Trajectory Following ◽  
Three Degree Of Freedom

In this paper, a novel hybrid position/force controller has been proposed for a three degree of freedom (3-DOF) of robot trajectory following that is required to switch between position and force control. The whole controller consists of two components: a positional controller and a force controller. Depending on whether the end-effector is in free space or in contact with the environments during work, the two subcontrollers run simultaneously to guide the manipulator tracking in free space and constraint environments. After the principle and stability of the controller are briefly analyzed, simulation results verify that the proposed controller attains a high performance.

Analysis of Hand-Arm Coordinate Motion on Constraint Tasks

1991 ◽  
Vol 3 (6) ◽  
pp. 497-505
Author(s):  
Shigeki Sugano ◽  
◽  
Hideyo Namimoto ◽  
Ichiro Kato
Keyword(s):  
Control Strategy ◽  
Force Control ◽  
Degrees Of Freedom ◽  
Control Mechanism ◽  
Human Motion ◽  
Degree Of Freedom ◽  
Human Hand ◽  
Human Motion Analysis ◽  
Manipulator Control ◽  
Arm Coordination

This research was conducted to study the control strategy of manipulator based on clarifying the force control mechanism of the human hand-arm by analyzing human constraint tasks with respect to biomechanism. In this paper; we describe an investigation of hand-arm function share. In addition, we apply hand-arm coordination to manipulator control using experimental results of analyzing the human tasks of moving bead balls on a shaft, which is an example of a constraint task with one degree of freedom (d.o.f.). In the human motion analysis, 6 axes of force on the task object are measured and compared in the case of constraining the hands degree of freedom and making hand free as well as in the case of with or without forced displacement along the translational direction during motion. As a result, we found that human work was performed smoothly through absorption of rotational force using hand d.o.f. and translational force using arm d.o.f. Also, it was found that there are the direction of motion and the posture easily absorbable translational force. Finally, we propose to apply the human hand-arm coordination compliance control strategy setting translational compliance by arms and rotational compliance by hands, to manipulator with more than 7 degrees of freedom. Thus, the setting of optional compliance applicable to circumstance and the resulting force control due to this become possible.

A Compact 3 Degree of Freedom Spherical Joint

2011 ◽  
Vol 3 (3) ◽  
Author(s):  
Mark L. Guckert ◽  
Michael D. Naish
Keyword(s):  
Control Systems ◽  
Degrees Of Freedom ◽  
Closed Loop ◽  
Degree Of Freedom ◽  
Robotic Systems ◽  
Closed Loop Control ◽  
Spherical Joint ◽  
Experimental Assessment ◽  
Loop Control ◽  
Robotic Applications

Spherical joints have evolved into a critical component of many robotic systems, often used to provide dexterity at the wrist of a manipulator. In this work, a novel 3 degree of freedom spherical joint is proposed, actuated by tendons that run along the surface of the sphere. The joint is mechanically simple and avoids mechanical singularities. The kinematics and mechanics of the joint are modeled and used to develop both open- and closed-loop control systems. Simulated and experimental assessment of the joint performance demonstrates that it can be successfully controlled in 3 degrees of freedom. It is expected that the joint will be a useful option in the development of emerging robotic applications, particularly those requiring miniaturization.

Matlab RTW-based Internet Accessible Remote Laboratory for Teaching Robot Control

2012 ◽  
pp. 362-379
Author(s):  
Zdenko Kovacic ◽  
Davor Jerbic ◽  
Vedran Vojvoda ◽  
Siniša Dujmovic
Keyword(s):  
Real Time ◽  
Management System ◽  
Web Application ◽  
Robot Control ◽  
Degrees Of Freedom ◽  
Robotic Systems ◽  
Remote Laboratory ◽  
Scara Robot ◽  
Control Schemes

This chapter describes the use of Matlab Real Time Workshop (RTW) for implementing an Internet Accessible Laboratory (IAL) for teaching robot control. The IAL architecture consists of three key components - IAL Web Application, IAL database, and a set of robot control schemes prepared for students’ laboratory curriculum that are running in Matlab RTW. The IAL management system supports multilingual access and enables easy addition of new users, new robotic systems, and new laboratory exercises related to robot control. The IAL functionality is demonstrated with the example of controlling a four degrees of freedom SCARA robot.

scholarly journals Pinching at Fingertips for Humanoid Robot Hand

2005 ◽  
Vol 17 (6) ◽  
pp. 655-663 ◽  
Author(s):  
Kiyoshi Hoshino ◽  
◽  
Ichiro Kawabuchi ◽  
Keyword(s):  
Force Control ◽  
Degrees Of Freedom ◽  
Humanoid Robot ◽  
Degree Of Freedom ◽  
Robot Hand ◽  
Motor Functions ◽  
Weak Force ◽  
Robot Hands ◽  
Finger Motion

Delicate actions such as picking up paper or a needle with the fingertips – an important function for robot hands – are extremely difficult. We propose a lightweight robot hand based on extracting minimum required motor functions and implementing them in a robot. We also propose a robot hand that realizes appropriate pinching by adding the minimum required degree of supplementary freedom realizable only mechanically. In the robot hand, we focus mainly on adding degrees of freedom for independent finger motion to the terminal joints and a degree of freedom for twisting by the thumb. The results showed that providing the fingertip with a joint with broad force control even with weak force effectively ensures delicate fingertip control in a humanoid robot hand.

Analytical Determination of Principal Twists and Singular Directions in Robot Manipulators

2003 ◽  
Author(s):  
Sandipan Bandyopadhyay ◽  
Ashitava Ghosal
Keyword(s):  
Degrees Of Freedom ◽  
Riemannian Metric ◽  
Degree Of Freedom ◽  
Body Motion ◽  
Inner Product ◽  
Analytical Determination ◽  
End Effector ◽  
Singular Configurations ◽  
Analytical Expressions

The identification of principal twists of the end-effector of a manipulator undergoing multi-degree-of-freedom motion is considered to be one of the central problems in kinematics. In this paper, we use dual velocity vectors to parameterize se(3), the space of twists, and define an inner product of two dual velocities as a dual number analog of a Riemannian metric on SE(3). We show that the principal twists can be obtained from the solution of an eigenvalue problem associated with this dual metric. It is shown that the computation of principal twists for any degree-of-freedom (DoF) of rigid-body motion, requires the solution of at most a cubic dual characteristic equation. Furthermore, the special nature of the coefficients yields simple analytical expressions for the roots of the dual cubic, and this in turn leads to compact analytical expressions for the principle twists. We also show that the method of computation allows us to separately identify the rotational and translational degrees-of-freedom lost or gained at singular configurations. The theory is applicable to serial, parallel, and hybrid manipulators, and is illustrated by obtaining the principal twists and singular directions for a 3-DoF parallel, and a hybrid 6-DoF manipulator.

A 7R-Based, Two Degrees of Freedom Robomech

2000 ◽  
Author(s):  
Ahmad A. Smaili
Keyword(s):  
Degrees Of Freedom ◽  
Parallel Architecture ◽  
Degree Of Freedom ◽  
Robot Arm ◽  
End Effector ◽  
Kinematic Constraints ◽  
Two Degrees Of Freedom ◽  
Synthesis Procedure ◽  
Two Degree Of Freedom

Abstract A robomech is a crossbreed of a mechanism and a robot arm. It has a parallel architecture equipped with more than one end effector to accomplish tasks that require the coordination of many functions. Robomechs with multi degrees of freedom that are based on the 4R and 5R chains have found their way into the literature. This article presents a new, two-degree of freedom robomech whose architecture is based on the 7R chain. The robomech is capable of performing two-function tasks. The features, kinematic constraints, and synthesis procedure of the robomech are outlined and an application example is given.

Educational Force Control Using a Modular 2-DOF Serial Robot Manipulator and Low-Cost 2-DOF Force Sensor

2019 ◽  
Author(s):  
Stephen Mascaro
Keyword(s):  
Force Control ◽  
Degrees Of Freedom ◽  
Hybrid Control ◽  
Robot Manipulator ◽  
Impedance Control ◽  
Low Cost ◽  
Force Sensor ◽  
Physical Contact ◽  
Dynamic Force ◽  
Control Techniques

Abstract This paper describes a modular 2-DOF serial robotic system and accompanying experiments that have been developed to instruct robotics students in the fundamentals of dynamic force control. In prior work, we used this same robot to showcase and compare the performance of a variety of textbook techniques for dynamic motion control (i.e. fast/accurate trajectory tracking using dynamic model-based and robust control techniques). In this paper we now add a low-cost 3D-printed 2-DOF force sensor to this modular robot and demonstrate a variety of force control techniques for use when the robot is in physical contact with the environment. These include stiffness control, impedance control, admittance control, and hybrid position/force control. Each of these various force control schemes can be first simulated and then experimentally implemented using a MATLAB/Simulink real-time interface. The two-degrees of freedom are just enough to demonstrate how the manipulator Jacobian can be used to implement directional impedances in operational space, and to demonstrate how hybrid control can implement position and force control in different axes. This paper will describe the 2-DOF robot system including the custom force sensor, illustrate the various force control methods that can be implemented, and demonstrate sample results from these experiments.

Design and control of a three degree of freedom pneumatic physiotherapy robot

Robotica ◽  
2003 ◽  
Vol 21 (6) ◽  
pp. 589-604 ◽  
Author(s):  
R. Richardson ◽  
M. Brown ◽  
B. Bhakta ◽  
M.C. Levesley
Keyword(s):  
Degrees Of Freedom ◽  
Impedance Control ◽  
Human Subjects ◽  
Degree Of Freedom ◽  
Common Condition ◽  
Controller Performance ◽  
Significant Disability ◽  
Impedance Parameters ◽  
Three Degree Of Freedom ◽  
And Control

Stroke is a common condition resulting in 30,000 people per annum left with significant disability. In patients with severe arm paresis after stroke, functional recovery in the affected arm is poor. Inadequate intensity of treatment is cited as one factor accounting for the lack of arm recovery found in some studies. Given that physical therapy resource is limited, strategies to enhance the physiotherapists' efforts are needed. One approach is to use robotic techniques to augment movement therapy.A three degree-of-freedom pneumatic robot has been developed to apply physiotherapy to the upper limb. The robot has been designed with a workspace encompassing the reach-retrieve range of the average male. Control experiments have applied force and then position only controllers to the pneumatic robot. These controllers are combined to form a position-based impedance control strategy on all degrees of freedom of the robot. The impedance controller performance was found to be dependent upon the specified impedance parameters. Initial experiments attaching the device to human subjects have indicated great potential for the device.

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