scholarly journals FUZZY CONTROL OF DIFFERENTIAL DRIVE MOBILE ROBOT FOR MOVING TARGET TRACKING

2017 ◽  
Vol 16 (2) ◽  
pp. 83
Author(s):  
Emina Petrović ◽  
Miloš Simonović ◽  
Vlastimir Nikolić
Keyword(s):  
Mobile Robot ◽  
Moving Objects ◽  
Mobile Robotics ◽  
Position Control ◽  
Hierarchical Control ◽  
Circular Path ◽  
Level Control ◽  
Low Level ◽  
Angular Velocities ◽  
High Level

Tracking of moving objects, including humans has important role in mobile robotics. In this paper, the hierarchical control structure for target/human tracking consisted of high and low level control was presented. The low level subsystem deals with the control of the linear and angular velocities using multivariable PD controller whose parameters are obtained by Particle swarm optimization. The position control of the mobile robot represents the high level control, where we use two fuzzy logic Mamdani controllers for distance and angle control. In order to test the effectiveness of the proposed control scheme a simulation was performed. Two cases, when the mobile robot pursues a target moving along a circular path and when the mobile robot pursues a target moving along a rectangle path, were simulated.

scholarly journals Mobile Robotics in Agricultural Operations: A Narrative Review on Planning Aspects

2020 ◽  
Vol 10 (10) ◽  
pp. 3453 ◽  
Author(s):  
Vasileios Moysiadis ◽  
Naoum Tsolakis ◽  
Dimitris Katikaridis ◽  
Claus G. Sørensen ◽  
Simon Pearson ◽  
...  
Keyword(s):  
Mobile Robots ◽  
Mobile Robotics ◽  
Narrative Review ◽  
Level Control ◽  
Relevant Research ◽  
World Model ◽  
Level Ii ◽  
Agricultural Operations ◽  
Definition Of ◽  
High Level

The advent of mobile robots in agriculture has signaled a digital transformation with new automation technologies optimize a range of labor-intensive, resources-demanding, and time-consuming agri-field operations. To that end a generally accepted technical lexicon for mobile robots is lacking as pertinent terms are often used interchangeably. This creates confusion among research and practice stakeholders. In addition, a consistent definition of planning attributes in automated agricultural operations is still missing as relevant research is sparse. In this regard, a “narrative” review was adopted (1) to provide the basic terminology over technical aspects of mobile robots used in autonomous operations and (2) assess fundamental planning aspects of mobile robots in agricultural environments. Based on the synthesized evidence from extant studies, seven planning attributes have been included: (i) high-level control-specific attributes, which include reasoning architecture, the world model, and planning level, (ii) operation-specific attributes, which include locomotion–task connection and capacity constraints, and (iii) physical robot-specific attributes, which include vehicle configuration and vehicle kinematics.

Powered Ankle-Foot Prostheses: A Survey on Sensing Systems and Control Strategies

2019 ◽  
Author(s):  
Erik Chumacero-Polanco ◽  
James Yang
Keyword(s):  
Control Strategies ◽  
Level Control ◽  
Low Level ◽  
Kinetic Information ◽  
Sensing Systems ◽  
Systems And Control ◽  
Finite State ◽  
High Level ◽  
And Control

Abstract People who have suffered a transtibial amputation show diminished ambulation and impaired quality of life. Powered ankle foot prostheses (AFP) are used to recover some mobility of transtibial amputees (TTAs). Powered AFP is an emerging technology that has great potential to improve the quality of life of TTAs with important avenues for research and development in different fields. This paper presents a survey on sensing systems and control strategies applied to powered AFPs. Sensing kinematic and kinetic information in powered AFPs is critical for control. Ankle angle position is commonly obtained via potentiometers and encoders directly installed on the joint, velocities can be estimated using numerical differentiators, and accelerations are normally obtained via inertial measurement units (IMUs). On the other hand, kinetic information is usually obtained via strain gauges and torque sensors. On the other hand, control strategies are classified as high- and low-level control. The high-level control sets the torque or position references based on pattern generators, user’s intent of motion recognition, or finite-state machine. The low-level control usually consists of linear controllers that drive the ankle’s joint position, velocity, or torque to follow an imposed reference signal. The most widely used control strategy is the one based on finite-state machines for the high-level control combined with a proportional-derivative torque control for low-level. Most designs have been experimentally assessed with acceptable results in terms of walking speed. However, some drawbacks related to powered AFP’s weight and autonomy remain to be overcome. Future research should be focused on reducing powered AFP size and weight, increasing energy efficiency, and improving both the high- and the low-level controllers in terms of efficiency and performance.

Robust Bipedal Locomotion Based on a Hierarchical Control Structure

Robotica ◽  
2019 ◽  
Vol 37 (10) ◽  
pp. 1750-1767 ◽  
Author(s):  
Jianwen Luo ◽  
Yao Su ◽  
Lecheng Ruan ◽  
Ye Zhao ◽  
Donghyun Kim ◽  
...  
Keyword(s):  
Center Of Pressure ◽  
Center Of Mass ◽  
Hierarchical Control ◽  
Middle Level ◽  
Smooth Transition ◽  
Whole Body ◽  
Joint Torques ◽  
Low Level ◽  
Hybrid Controller ◽  
High Level

SummaryTo improve biped locomotion’s robustness to internal and external disturbances, this study proposes a hierarchical structure with three control levels. At the high level, a foothold sequence is generated so that the Center of Mass (CoM) trajectory tracks a planned path. The planning procedure is simplified by selecting the midpoint between two consecutive Center of Pressure (CoP) points as the feature point. At the middle level, a novel robust hybrid controller is devised to drive perturbed system states back to the nominal trajectory within finite cycles without chattering. The novelty lies in that the hybrid controller is not subject to linear CoM dynamic constraints. The hybrid controller consists of two sub-controllers: an oscillation controller and a smoothing controller. For the oscillation controller, the desired CoM height is specified as a sine-shaped function, avoiding a new attractive limit cycle. However, this controller results in the inevitable chattering because of discontinuities. A smoothing controller provides continuous properties and thus can inhibit the chattering problem, but has a smaller region of attraction compared with the oscillation controller. A hybrid controller merges the two controllers for a smooth transition. At the low level, the desired CoM motion is defined as tasks and embedded in a whole body operational space (WBOS) controller to compute the joint torques analytically. The novelty of the low-level controller lies in that within the WBOS framework, CoM motion is not subject to fixed CoM dynamics and thus can be generalized.

Whole-Body Balancing Walk Controller for Position Controlled Humanoid Robots

2016 ◽  
Vol 13 (01) ◽  
pp. 1650011 ◽  
Author(s):  
Seung-Joon Yi ◽  
Byoung-Tak Zhang ◽  
Dennis Hong ◽  
Daniel D. Lee
Keyword(s):  
Hierarchical Control ◽  
Humanoid Robots ◽  
Whole Body ◽  
Appropriate Behavior ◽  
Low Level ◽  
Push Recovery ◽  
Hierarchical Control Architecture ◽  
High Level ◽  
Experimental Trials ◽  
Decision Boundaries

Bipedal humanoid robots are intrinsically unstable against unforeseen perturbations. Conventional zero moment point (ZMP)-based locomotion algorithms can reject perturbations by incorporating sensory feedback, but they are less effective than the dynamic full body behaviors humans exhibit when pushed. Recently, a number of biomechanically motivated push recovery behaviors have been proposed that can handle larger perturbations. However, these methods are based upon simplified and transparent dynamics of the robot, which makes it suboptimal to implement on common humanoid robots with local position-based controllers. To address this issue, we propose a hierarchical control architecture. Three low-level push recovery controllers are implemented for position controlled humanoid robots that replicate human recovery behaviors. These low-level controllers are integrated with a ZMP-based walk controller that is capable of generating reactive step motions. The high-level controller constructs empirical decision boundaries to choose the appropriate behavior based upon trajectory information gathered during experimental trials. Our approach is evaluated in physically realistic simulations and on a commercially available small humanoid robot.

Implementation of robotic ankle–foot orthosis with an impedance-based assist-as-needed control strategy

2021 ◽  
pp. 1-40
Author(s):  
Bing Chen ◽  
Bin Zi ◽  
Bin Zhou ◽  
Zhengyu Wang
Keyword(s):  
Level Control ◽  
Ankle Foot Orthosis ◽  
Low Level ◽  
Ankle Impedance ◽  
Torque Generation ◽  
Ankle Rehabilitation ◽  
Finite State ◽  
Proportional Derivative Controller ◽  
High Level ◽  
Foot Orthosis

Abstract In this paper, a robotic ankle–foot orthosis (AFO) is developed for individuals with a paretic ankle, and an impedance-based assist-as-needed controller is designed for the robotic AFO to provide adaptive assistance. First, a description of the robotic AFO hardware design is presented. Next, the design of the finite state machine is introduced, followed by an introduction to the modelling of the robotic AFO. Additionally, the control of the robotic AFO is presented. An impedance-based high-level controller that is composed of an ankle impedance based torque generation controller and an impedance controller is designed for the high-level control. A compensated low-level controller that is composed of a braking controller and a proportional-derivative controller with a compensation part is designed for the low-level control. Finally, a pilot study is conducted, and the experimental results demonstrate that with the proposed control algorithm, the robotic AFO has the potential for ankle rehabilitation by providing adaptive assistance. In the assisted condition with a high level of assistance, reductions of 8% and 20.1% of the root mean square of the tibialis anterior and lateral soleus activities are observed, respectively.

Analysis and Control Design of a Hydro-Mechanical Hydraulic Hybrid Passenger Vehicle

2009 ◽  
Author(s):  
Teck Ping Sim ◽  
Perry Y. Li
Keyword(s):  
Control Systems ◽  
Torque Control ◽  
Mechanical Transmission ◽  
Control Analysis ◽  
Passenger Vehicle ◽  
Level Control ◽  
Analysis And Design ◽  
Low Level ◽  
Hydraulic Hybrid ◽  
High Level

This paper gives the dynamic analysis of a hydro-mechanical transmission (HMT) drive train with regeneration and independent wheel torque control of a hydraulic hybrid passenger vehicle. From this analysis, we formulate the HMT control system, which is made up of high, mid and low-level control systems. The high-level consists of a state of charge management and the mid-level translates the storage requirement specified by the high-level into desired internal speed and gear ratio to be executed by the low-level. In this paper we focus on the low-level control analysis and design, where the actuation authority to regulate the internal speed variable comes from either the engine (mode 1) or the hydraulic system (mode 2). Experimental studies show good tracking performance of the proposed control systems and enable our vehicle system to be driven in the proposed HMT architecture.

Modeling and Robust Low Level Control of an Omnidirectional Mobile Robot

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Ramon Comasolivas ◽  
Joseba Quevedo ◽  
Teresa Escobet ◽  
Antoni Escobet ◽  
Juli Romera
Keyword(s):  
Mobile Robot ◽  
Pi Controller ◽  
Control Technique ◽  
Level Control ◽  
Parameter Uncertainties ◽  
Control Effort ◽  
Friction Forces ◽  
Low Level ◽  
Stability And Control ◽  
And Control

This paper presents the modeling and robust low-level control design of a redundant mobile robot with four omnidirectional wheels, the iSense Robotic (iSRob) platform, that was designed to test safe control algorithms. iSRob is a multivariable nonlinear system subject to parameter uncertainties mainly due to friction forces. A multilinear model is proposed to approximate the behavior of the system, and the parameters of these models are estimated from closed-loop experimental data applying Gauss–Newton techniques. A robust control technique, quantitative feedback theory (QFT), is applied to design a proportional–integral (PI) controller for robust low-level control of the iSRob system, being this the main contribution of the paper. The designed controller is implemented, tested, and compared with a gain-scheduling PI-controller based on pole assignment. The experimental results show that robust stability and control effort margins against system uncertainties are satisfied and demonstrate better performance than the other controllers used for comparison.

Hierarchical safety supervisory control strategy for robot-assisted rehabilitation exercise

Robotica ◽  
2013 ◽  
Vol 31 (5) ◽  
pp. 757-766 ◽  
Author(s):  
Lizheng Pan ◽  
Aiguo Song ◽  
Guozheng Xu ◽  
Huijun Li ◽  
Baoguo Xu ◽  
...  
Keyword(s):  
Control Strategy ◽  
Therapeutic Process ◽  
Hierarchical Control ◽  
Hierarchical Architecture ◽  
Robot Assisted ◽  
Low Level ◽  
Emergency Situations ◽  
Impaired Limb ◽  
High Level ◽  
Rehabilitation Exercise

SUMMARYClinical outcomes have shown that robot-assisted rehabilitation is potential of enhancing quantification of therapeutic process for patients with stroke. During robotic rehabilitation exercise, the assistive robot must guarantee subject's safety in emergency situations, e.g., sudden spasm or twitch, abruptly severe tremor, etc. This paper presents a hierarchical control strategy, which is proposed to improve the safety and robustness of the rehabilitation system. The proposed hierarchical architecture is composed of two main components: a high-level safety supervisory controller (SSC) and low-level position-based impedance controller (PBIC). The high-level SSC is used to automatically regulate the desired force for a reasonable disturbance or timely put the emergency mode into service according to the evaluated physical state of training impaired limb (PSTIL) to achieve safety and robustness. The low-level PBIC is implemented to achieve compliance between the robotic end-effector and the impaired limb during the robot-assisted rehabilitation training. The results of preliminary experiments demonstrate the effectiveness and potentiality of the proposed method for achieving safety and robustness of the rehabilitation robot.

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