Adaptive Motion and Force Control of Robots Performing a Complete Task

1999 ◽  
Author(s):  
Prabhakar R. Pagilla ◽  
Biao Yu
Keyword(s):  
Force Control ◽  
Position Control ◽  
Active Phase ◽  
Free Motion ◽  
Constrained Motion ◽  
Control Laws ◽  
Adaptive Motion ◽  
Inactive Phase ◽  
The Impact ◽  
Three Phases

Abstract In this work, we consider adaptive motion and force control of a robot performing a complete task. By a complete task we mean that the robot desired task contains both free motion and constrained motion. Further, we also consider transition from free motion to constrained motion. We divide the motion of the robot into three phases: (i) inactive phase, where the robot is in free motion, (ii) transition phase, where the transition from free motion to constrained motion takes place, and (iii) active phase, where the robot is in constrained motion with simultaneous force and position control. Uncertainty of the constraint results in the impact of robot with the constraint surface when transition from free motion to constrained motion. We design stable control laws for the three phases that results in an efficient algorithm for robots performing a complete task. Extensive experiments are conducted to show the validity of the proposed control designs.

Application of redundant robots to constrained-motion tasks

Robotica ◽  
1992 ◽  
Vol 10 (5) ◽  
pp. 397-407 ◽  
Author(s):  
Veljko Potkonjak
Keyword(s):  
Free Motion ◽  
Constrained Motion ◽  
End Effector ◽  
Redundant Robot ◽  
Redundant Robots ◽  
Passive Compliance ◽  
Two Phases ◽  
The Impact

SUMMARYThe problem of the constrained motion of robot end-effector is discussed. The redundant robot is considered, redundancy being added in order to improve robot working characteristics. In the phase of free motion towards the constraint the errors of basic non-redundant configuration are corrected by means of redundancy. During the constrained motion redundancy plays the role either of active or passive compliance. Between these two phases, the collision with the constraint occurs, and the impact can be absorbed by using redundancy.

Robotic constant force grinding control based on grinding model and iterative algorithm

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Meng Xiao ◽  
Tie Zhang ◽  
Yanbiao Zou ◽  
Shouyan Chen
Keyword(s):  
Iterative Algorithm ◽  
Contact Force ◽  
Force Control ◽  
Control Algorithm ◽  
Position Control ◽  
Normal Force ◽  
Rbf Neural Network ◽  
Processing Stage ◽  
Content Type ◽  
The Impact

Purpose The purpose of this paper is to propose a robot constant grinding force control algorithm for the impact stage and processing stage of robotic grinding. Design/methodology/approach The robot constant grinding force control algorithm is based on a grinding model and iterative algorithm. During the impact stage, active disturbance rejection control is used to plan the robotic reference contact force, and the robot speed is adjusted according to the error between the robot’s real contact force and the robot’s reference contact force. In the processing stage, an RBF neural network is used to construct a model with the robot's position offset displacement and controlled output, and the increment of control parameters is estimated according to the RBF neural network model. The error of contact force and expected force converges gradually by iterating the control parameters online continuously. Findings The experimental results show that the normal force overshoot of the robot based on the grinding model and iterative algorithm is small, and the processing convergence speed is fast. The error between the normal force and the expected force is mostly within ±3 N. The normal force based on the force control algorithm is more stable than the normal force based on position control, and the surface roughness of the processed workpiece has also been improved, the Ra value compared with position control has been reduced by 24.2%. Originality/value As the proposed approach obtains a constant effect in the impact stage and processing stage of robot grinding and verified by the experiment, this approach can be used for robot grinding for improved machining accuracy.

scholarly journals Robust Position Control of a Two-Sided 1-DoF Impacting Mechanical Oscillator Subject to an External Persistent Disturbance by Means of a State-Feedback Controller

Complexity ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Firas Turki ◽  
Hassène Gritli ◽  
Safya Belghith
Keyword(s):  
State Feedback ◽  
Position Control ◽  
External Disturbance ◽  
Feedback Controller ◽  
Linear Matrix ◽  
Stability Conditions ◽  
Mechanical Oscillator ◽  
Impact Oscillator ◽  
State Feedback Controller ◽  
The Impact

This paper proposes a state-feedback controller using the linear matrix inequality (LMI) approach for the robust position control of a 1-DoF, periodically forced, impact mechanical oscillator subject to asymmetric two-sided rigid end-stops. The periodic forcing input is considered as a persistent external disturbance. The motion of the impacting oscillator is modeled by an impulsive hybrid dynamics. Thus, the control problem of the impact oscillator is recast as a problem of the robust control of such disturbed impulsive hybrid system. To synthesize stability conditions, we introduce the S-procedure and the Finsler lemmas by only considering the region within which the state evolves. We show that the stability conditions are first expressed in terms of bilinear matrix inequalities (BMIs). Using some technical lemmas, we convert these BMIs into LMIs. Finally, some numerical results and simulations are given. We show the effectiveness of the designed state-feedback controller in the robust stabilization of the position of the impact mechanical oscillator under the disturbance.

scholarly journals Neural Network Based Contact Force Control Algorithm for Walking Robots

Sensors ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 287
Author(s):  
Byeongjin Kim ◽  
Soohyun Kim
Keyword(s):  
Neural Network ◽  
Contact Force ◽  
Force Control ◽  
Control Algorithm ◽  
Position Control ◽  
Linear Quadratic Regulator ◽  
Walking Robots ◽  
Test Model ◽  
Linear Quadratic ◽  
Contact Force Control

Walking algorithms using push-off improve moving efficiency and disturbance rejection performance. However, the algorithm based on classical contact force control requires an exact model or a Force/Torque sensor. This paper proposes a novel contact force control algorithm based on neural networks. The proposed model is adapted to a linear quadratic regulator for position control and balance. The results demonstrate that this neural network-based model can accurately generate force and effectively reduce errors without requiring a sensor. The effectiveness of the algorithm is assessed with the realistic test model. Compared to the Jacobian-based calculation, our algorithm significantly improves the accuracy of the force control. One step simulation was used to analyze the robustness of the algorithm. In summary, this walking control algorithm generates a push-off force with precision and enables it to reject disturbance rapidly.

scholarly journals Effect of a Neuropeptide Gene on Behavioral States in Caenorhabditis elegans Egg-Laying

Genetics ◽  
2000 ◽  
Vol 154 (3) ◽  
pp. 1181-1192 ◽  
Author(s):  
Laura E Waggoner ◽  
Laura Anne Hardaker ◽  
Steven Golik ◽  
William R Schafer
Keyword(s):  
Caenorhabditis Elegans ◽  
Active Phase ◽  
Egg Laying ◽  
Sensory Cues ◽  
Nematode Caenorhabditis Elegans ◽  
Inactive State ◽  
Recessive Mutations ◽  
Inactive Phase ◽  
Behavioral States ◽  
Stimulation Of

Abstract Egg-laying behavior in the nematode Caenorhabditis elegans involves fluctuation between alternative behavioral states: an inactive state, during which eggs are retained in the uterus, and an active state, during which eggs are laid in bursts. We have found that the flp-1 gene, which encodes a group of structurally related neuropeptides, functions specifically to promote the switch from the inactive to the active egg-laying state. Recessive mutations in flp-1 caused a significant increase in the duration of the inactive phase, yet egg-laying within the active phase was normal. This pattern resembled that previously observed in mutants defective in the biosynthesis of serotonin, a neuromodulator implicated in induction of the active phase. Although flp-1 mutants were sensitive to stimulation of egg-laying by serotonin, the magnitude of their serotonin response was abnormally low. Thus, the flp-1-encoded peptides and serotonin function most likely function in concert to facilitate the onset of the active egg-laying phase. Interestingly, we observed that flp-1 is necessary for animals to down-regulate their rate of egg-laying in the absence of food. Because flp-1 is known to be expressed in interneurons that are postsynaptic to a variety of chemosensory cells, the FLP-1 peptides may function to regulate the activity of the egg-laying circuitry in response to sensory cues.

scholarly journals Can the adoption of informal approaches to learning music in school music lessons promote musical progression?

2017 ◽  
Vol 34 (2) ◽  
pp. 127-151 ◽  
Author(s):  
Susan Hallam ◽  
Andrea Creech ◽  
Hilary McQueen
Keyword(s):  
Focus Groups ◽  
Music Teachers ◽  
Approaches To Learning ◽  
Musical Skills ◽  
Music Lessons ◽  
Stage 4 ◽  
School Music ◽  
The Impact ◽  
Three Phases

The aim of this research was to explore the impact of the adoption of the Musical Futures approach on the musical progression of students in Musical Futures’ Champion schools. The research took place over three years in three phases with 733 students and 28 music teachers completing questionnaires. Data from the interviews with 39 staff and focus groups of 325 students provided greater insights into the questionnaire responses. Overall, teachers reported that Musical Futures had enhanced the musical progression of their students and increased take up at Key Stage 4. In some cases this had led to changes in the qualifications on offer with an emphasis on those which were vocational rather than academic. This created some tensions in catering for the needs of different groups of students who had a range of different musical skills.

Sign in / Sign up

Export Citation Format

Share Document