Robotic Instrumented Complaint Wrist

1992 ◽  
Vol 114 (1) ◽  
pp. 120-123 ◽  
Author(s):  
Yangsheng Xu ◽  
R. P. Paul
Keyword(s):  
Force Control ◽  
Position Control ◽  
Contact Forces ◽  
Displacement Sensor ◽  
Robot Arm ◽  
Sensing Mechanism ◽  
Manufacturing Operations ◽  
Positioning Errors ◽  
Control Scheme ◽  
Passive Compliance

A robotic complaint wrist which combines a passive compliance device and a displacement sensor has been developed and tested. The device provides the necessary flexibility to accommodate transitions between the position control and force control modes, and avoid large impact forces as a robot makes contact with parts, as well as correct positioning errors and allow the relaxation of tolerances in assembly and manufacturing operations. The device installed between a robot arm and end-effector is composed of two parts: a passive compliance device and a sensing mechanism. The passive compliance is provided by a rubber structure; its configuration can be arranged to yield the desired stiffness ratio along and about each axis. The sensing mechanism consists of a six-joint serial linkage with a transducer at each point. The measured deflection is used to actively control the contact forces and compensate for the positioning error during motion and contact. In this paper, the design features of two prototypes of the device are described. A systematic hybrid position/force control scheme incorporating the device is presented.

scholarly journals Knowledge-Based Trajectory Error Pattern Method Applied to an Active Force Control Scheme

1970 ◽  
Vol 3 (1) ◽  
Author(s):  
Endra Pitowarno, Musa Mailah, Hishamuddin Jamaluddin
Keyword(s):  
Force Control ◽  
Error Pattern ◽  
Robot Arm ◽  
Active Force ◽  
Trajectory Error ◽  
Track Error ◽  
Knowledge Based ◽  
Inertia Matrix ◽  
Active Force Control ◽  
Control Scheme

The active force control (AFC) method is known as a robust control scheme that dramatically enhances the performance of a robot arm particularly in compensating the disturbance effects. The main task of the AFC method is to estimate the inertia matrix in the feedback loop to provide the correct (motor) torque required to cancel out these disturbances. Several intelligent control schemes have already been introduced to enhance the estimation methods of acquiring the inertia matrix such as those using neural network, iterative learning and fuzzy logic. In this paper, we propose an alternative scheme called Knowledge-Based Trajectory Error Pattern Method (KBTEPM) to suppress the trajectory track error of the AFC scheme. The knowledge is developed from the trajectory track error characteristic based on the previous experimental results of the crude approximation method. It produces a unique, new and desirable error pattern when a trajectory command is forced. An experimental study was performed using simulation work on the AFC scheme with KBTEPM applied to a two-planar manipulator in which a set of rule-based algorithm is derived. A number of previous AFC schemes are also reviewed as benchmark. The simulation results show that the AFC-KBTEPM scheme successfully reduces the trajectory track error significantly even in the presence of the introduced disturbances.Key Words:  Active force control, estimated inertia matrix, robot arm, trajectory error pattern, knowledge-based.

Controller Design Robust to Frequency Variation in a One-Link Flexible Robot Arm

1989 ◽  
Vol 111 (1) ◽  
pp. 9-14 ◽  
Author(s):  
V. V. Korolov ◽  
Y. H. Chen
Keyword(s):  
Position Control ◽  
Controller Design ◽  
Wide Spectrum ◽  
Operating Conditions ◽  
Frequency Variation ◽  
Robot Arm ◽  
Flexible Robot ◽  
Complete Knowledge ◽  
Control Scheme ◽  
Frequency Variations

The end-point position control problem of a one-link flexible robot arm under wide spectrum of operating conditions is considered. Natural frequency variations may arise in practice and are treated as the uncertainty. A robust control scheme is designed for the manipulator for some guaranteed performances without the complete knowledge of uncertainty. The only required information of the uncertainty is its possible bound.

Development of Flexible Inserter for IC Chip Testing

2001 ◽  
Vol 13 (3) ◽  
pp. 289-293
Author(s):  
Toshihiro Taguchi ◽  
Keyword(s):  
Force Control ◽  
Manufacturing Process ◽  
Semiconductor Manufacturing ◽  
Position Control ◽  
Electrical Characteristics ◽  
Pressing Force ◽  
Passive Compliance ◽  
Last Stage ◽  
Ic Testing ◽  
Chip Testing

In the last stage of semiconductor manufacturing process, IC is inserted in the testing equipment for many kinds of electrical characteristics test. But the use of position control causes many problems such as shortage or overdose of pressing force, the non-uniformity of pressing force, and the shoulder touch phenomenon of IC pressing etc. Thus the testing process with stable and flexibly efficient handler is desired. In this paper, focusing on IC packages such as BGA and CSP, the development of flexible inserter for IC testing based on force control and with a new passive compliance unit (PCU) is reported to improve testing throughput drastically.

Force-Controlled Assembly of two Objects with a Two-arm Robot

Robotica ◽  
1991 ◽  
Vol 9 (3) ◽  
pp. 299-306 ◽  
Author(s):  
Pierre Dauchez ◽  
Xavier Delebarre
Keyword(s):  
Position Control ◽  
Hybrid Control ◽  
Contact Forces ◽  
Rigid Object ◽  
Assembly Task ◽  
Control Scheme ◽  
The One ◽  
Theoretical Results ◽  
Hybrid Control Scheme ◽  
Approach Phase

SUMMARYThe use of a two-arm robot for assembling two objects, with each being held by one arm, is presented. The assembly task is decomposed into an approach phase and an assembly phase. For each phase, we propose a solution for describing the task. For the approach phase, we suggest to describe the task with respect to a mobile reference frame, attached to the end effector of one of the arms. This allows us to take advantage of the redundancy of the system. For the assembly phase, we propose two solutions, both involving some kind of force control. The first one is based upon a position control similar to the one used for the approach phase, with an updating of the reference position through a measurement of the contact forces. The second scheme is derived from a symmetrical hybrid control scheme initially proposed by Uchiyama and Dauchez to control a two-arm robot handling a single rigid object. The main results of this scheme are summarized, and the way of using it for an assembly task is presented. Finally, the experimental setup we have installed to validate our theoretical results is described.

Force Control of a Robot Arm During Contact Task

2002 ◽  
Author(s):  
A. Yetik ◽  
V. Karadag
Keyword(s):  
Force Control ◽  
Control Algorithm ◽  
Force Feedback ◽  
Impedance Control ◽  
Mechanical Impedance ◽  
Contact Forces ◽  
Working Environment ◽  
Robot Arm ◽  
Simulation Results ◽  
End Effectors

There are extremely important applications to investigate the control of contact between the end-effectors and the object. During controlling an object, static or in motion, the robot arm should not be damaged. Forces are important in such conditions. The forces between the end-effectors and the object have to be controlled. The motion of the robot arm changes forces. Thats why, to control forces, a force kontrol algorithm must be developed. Previous conventional force control algorithms could not control the robot effectively by only considering the variation of working environment. In this study, a control algorithm strategy to achieve the desired interactions forces between the robot end-effector and the environment during contact tasks, has been developed. The surface of the object and robot are very stiff, thus contact spring coefficient Kc is very large, because of this Kc effect, the results of the forces simulation results, but we get suitable results. Study include, modelling robot arm, evaluating measured forces during contact and constructing a suitable force control algorithm, dynamics, kinematics and simulation results. In this study, we used impedans control which the surface of the object is very stiff, as known as impedance control does not try to track position and force trajectories directly, but rather to regulate the dynamic relationship between the contact forces and manipulator positions, namely the mechanical impedance. Impedance control focused on the design of a robot’s dynamic behavior as seen from the environment. In this control strategy, no hardware or software, switch is needed in the robot’s control system when the robot travels from the free motion space to the constrained space. The force feedback loop closes naturally as soon as the robot interacts with the environment, which changes the robot’s impedance as seen from the environment. By controlling the manipulator positions, and regulating their relationship to the contact forces, the manipulator can be controlled to maintain appropriate contact forces.

scholarly journals Robust Position/Force Control of Constrained Flexible Joint Robots with Constraint Uncertainties

2020 ◽  
Vol 100 (3-4) ◽  
pp. 945-954
Author(s):  
Cumhur Baspinar
Keyword(s):  
Robust Control ◽  
Force Control ◽  
Position Control ◽  
Control Method ◽  
Contact Forces ◽  
Control Task ◽  
Flexible Joint ◽  
Flexible Joint Robots ◽  
Modeling Uncertainties ◽  
Contact Surfaces

AbstractA novel robust control method for simultaneous position/force control of constrained flexible joint robots is proposed. The facts that the uncertainties make the usual control task unsolvable and that the equations of the controlled system are differential-algebraic make the problem dealt with considerably demanding. In order to overcome the unsolvability problem due to the constraint uncertainties the position control task is redefined in a practical way such that only a suitable subgroup of the link positions are driven to their desired trajectories. To determine the elements of the subgroup a simple algorithm of practical relevance is proposed. Under certain smoothness conditions to the contact surfaces, it is demonstrated that the position control problem can dynamically be isolated from the force control. Thus, it becomes possible to handle the position and force control tasks separately. The most significant advantage of the separation of the position and force control tasks is that it makes possible to adapt the position control methods known from free robots. Each joint is used in either position control or force control. The proposed position controller has a cascaded structure: First, trajectories for joint positions that drive the link positions to their desired values are calculated. Then, the joint torques that drive the joint positions to their calculated values are determined. A further significant benefit of the separation of the position and force control tasks arises in the force control such that the transformed equations are linear and any linear robust control approach can be used for the force control. The whole controller requires the measurement of the link and joint positions, the link and joint velocities and the contact forces, and allows modeling uncertainties in the equations of both the robot dynamics and the contact surfaces. The proposed control method is also confirmed by simulations.

Control of a Robot Arm Using Iterative Learning Algorithm with a Stopping Criterion

2012 ◽  
Author(s):  
Musa Mailah ◽  
Wun Shiung Jonathan Chong
Keyword(s):  
Force Control ◽  
Robot Control ◽  
Learning Algorithm ◽  
Iterative Learning ◽  
Operating Conditions ◽  
Robot Arm ◽  
Active Force ◽  
Stopping Criterion ◽  
Active Force Control ◽  
Control Scheme

Prestasi lasak bagi skema kawalan robot sangat perlu untuk memastikan robot dapat bekerja dengan berkesan seperti yang dikehendaki dalam persekitaran terbatas melibatkan gangguan, perubahan parameter, ketidaktentuan dan kepelbagaian keadaan operasi. Kajian yang dibuat adalah berkaitan dengan satu skema kawalan daya aktif dan algoritma pembelajaran berlelaran (AFCAIL) yang melibatkan satu ciri pembaikan dalam bentuk penggunaan kriteria memberhenti yang sesuai dimuatkan dalam strategi kawalan. Skema tersebut digunapakai terhadap sistem pengolah robotik planar berlengan–dua yang beroperasi secara mendatar. Kriteria memberhenti yang dicadangkan adalah reka bentuk untuk memberhentikan proses pembelajaran berlelaran apabila syarat atau keadaan berkaitan dengan kejituan ketika melakukan tugas serta perolehan matriks inersia anggaran pengolah yang dikehendaki dapat dipenuhi. Dengan cara demikian, robot dikatakan dapat beroperasi dengan baik sebagaimana yang diarahkan. Keberkesanan skema juga dikaji dengan mengambil kira beberapa keadaan bebanan dan operasi. Kata kunci: Robot; kawalan daya aktif; algoritma pembelajaran berlelaran; kriterion memberhenti The robust performance of a robot control scheme is vital to ensure that the robot accomplishes its tasks desirably in a constraint environment involving disturbances, parametric changes, uncertainties and varied operating conditions. The study introduces the Active Force Control and Iterative Learning Algorithm (AFCAIL) scheme with an improved feature in the form of a suitably designed stopping criterion incorporated in the control strategy. The scheme is applied to the control of a horiziontally operated robotic two–link planar manipulator. The proposed stopping criterion is specifically designed to halt the iterative learning process when the conditions related to the accuracy of the performed tasks and the acquisition of appropriate estimated inertia matrix of the robot arm are favourably met. In this way, the robot is said to perform desirably and excellently. The effectiveness of the scheme is also investigated by considering a number different loading and operating conditions. Key words: Robot; active force control; iterative learning algorithm; stopping criterion

Hybrid position/force control of 6-dof hydraulic parallel manipulator using force and vision

2016 ◽  
Vol 43 (3) ◽  
pp. 274-283 ◽  
Author(s):  
Changhong Gao ◽  
Dacheng Cong ◽  
Xiaochu Liu ◽  
Zhidong Yang ◽  
Han Tao
Keyword(s):  
Relative Position ◽  
Force Control ◽  
Parallel Manipulator ◽  
Vision System ◽  
Ccd Camera ◽  
Contact Forces ◽  
Outer Loop ◽  
Position Information ◽  
Content Type ◽  
Control Scheme

Purpose The purpose of this paper is to propose a hybrid position/force control scheme using force and vision for docking task of a six degrees of freedom (6-dof) hydraulic parallel manipulator (HPM). Design/methodology/approach The vision system consisted of a charge-coupled device (CCD) camera, and a laser distance sensor is used to provide globe relative position information. Also, a force plate is used to measure local contact forces. The proposed controller has an inner/outer loop structure. The inner loop takes charge of tracking command pose signals from outer loop as accurate as possible, while the outer loop generates the desired tracking trajectory according to force and vision feedback information to guarantee compliant docking. Several experiments have been performed to validate the performance of the proposed control scheme. Findings Experiment results show that the system has good performance of relative position tracking and compliant contact. In whole docking dynamic experiment, the amplitudes of contact forces are well controlled within 300 N, which can meet perfectly the requirement of the amplitude being not more than 1,000 N. Originality/value A hybrid position/force control scheme using force and vision is proposed to make a 6-dof HPM dock with a moving target object compliantly.

Research on Velocity Servo-Based Hybrid Position/Force Control Scheme for a Grinding Robot

2012 ◽  
Vol 490-495 ◽  
pp. 589-593 ◽  
Author(s):  
Qing Wei Zhang ◽  
Li Li Han ◽  
Fang Xu ◽  
Kai Jia
Keyword(s):  
Force Control ◽  
Feedback Loop ◽  
Force Feedback ◽  
Position Control ◽  
Force Sensor ◽  
Robot Controller ◽  
Control Scheme ◽  
Exact Position ◽  
Grinding Tool ◽  
Data Signal

In this paper, a velocity servo-based hybrid position/force control scheme for a grinding robot is presented. It simultaneously performs stable force control and exact position control along curved surface for a grinding robot. The force feedback loop changing the force to velocity, which will be used in the velocity servo-based robot, can control the force directly and has a faster response. The position feedback loop controls the grinding tool in a desired trajectory in Cartesian space. An overview of the control algorithm as well as the force data signal processing and the communication between force sensor and robot controller is described.

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