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.

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.

Mechatronics Engineering on the Example of a Multipurpose Mobile Robot

2009 ◽  
Vol 147-149 ◽  
pp. 61-66 ◽  
Author(s):  
Marek Stania ◽  
Ralf Stetter
Keyword(s):  
Mobile Robot ◽  
Design Process ◽  
Level Control ◽  
Mechatronic System ◽  
Mechatronic Systems ◽  
Mechatronic Design ◽  
Planning And Control ◽  
And Control

This paper presents the patented mechanical concept for steering and level control of a mobile robot equipped with four driving units and the methods that lead to the development of this mechatronic system. The mobile robot exhibits excellent maneuverability and considerable advantages when moving in difficult environments such as rough landscapes. The paper discusses a refined approach to develop mechatronic systems which is based on the well-known V-model. The refined approach allows a conscious planning and control of a mechatronic design process.

scholarly journals Computing and Controlling Basins of Attraction in Multistability Scenarios

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
John Alexander Taborda ◽  
Fabiola Angulo
Keyword(s):  
Fixed Point ◽  
Periodic Orbit ◽  
Periodic Orbits ◽  
Basin Of Attraction ◽  
Basins Of Attraction ◽  
Control Technique ◽  
Unstable Periodic Orbits ◽  
Control Effort ◽  
Coexistence Of Attractors ◽  
And Control

The aim of this paper is to describe and prove a new method to compute and control the basins of attraction in multistability scenarios and guarantee monostability condition. In particular, the basins of attraction are computed only using a submap, and the coexistence of periodic solutions is controlled through fixed-point inducting control technique, which has been successfully used until now to stabilize unstable periodic orbits. In this paper, however, fixed-point inducting control is used to modify the domains of attraction when there is coexistence of attractors. In order to apply the technique, the periodic orbit whose basin of attraction will be controlled must be computed. Therefore, the fixed-point inducting control is used to stabilize one of the periodic orbits and enhance its basin of attraction. Then, using information provided by the unstable periodic orbits and basins of attractions, the minimum control effort to stabilize the target periodic orbit in all desired ranges is computed. The applicability of the proposed tools is illustrated through two different coupled logistic maps.

scholarly journals The Trade-Off between the Controller Effort and Control Quality on Example of an Electro-Pneumatic Final Control Element

Actuators ◽  
2019 ◽  
Vol 8 (1) ◽  
pp. 23 ◽  
Author(s):  
Michał Bartyś ◽  
Bartłomiej Hryniewicki
Keyword(s):  
Control Element ◽  
Time To Failure ◽  
Level Control ◽  
Control Effort ◽  
Control Value ◽  
Embedded Controller ◽  
Pneumatic Transducer ◽  
And Control ◽  
Mean Time ◽  
Selection Of

For many years, the programmable positioners have been widely applied in structures of modern electro-pneumatic final control elements. The positioner consists of an electro-pneumatic transducer, embedded controller, and measuring instrumentation. Electro-pneumatic transducers that are used in positioners are characterized by a relatively short mean time-to-failure. The practical and economical method of a reasonable prolongation of this time is proposed in this paper. It is principally based on assessment and minimizing the effort of the embedded controller. For this purpose, some measures were introduced: The control value variability, mean-time, and the cumulative controller’s effort. The diminishing of controller effort has significant practical repercussions because it reduces the intensity of mechanical wear of the final control element components. On the other hand, the reduction of the cumulative effort is important in the context of process economy due to limitation of the consumption of energy of compressed air supplying the final control element. Therefore, the minimization of control effort indicators has an impact on the increase of the functional safety and economics of the controlled process. The simulations were performed in the Matlab-Simulink environment with the use of the liquid level control system in which a phenomenological model of a final control element was deployed. As a result of the performed simulations, the recommendations regarding the selection of the structure of positioner controller were elaborated.

scholarly journals Development of a Low-Level Control System for the ROV Visor3

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Santiago Rúa ◽  
Rafael E. Vásquez
Keyword(s):  
Mathematical Model ◽  
Control System ◽  
Nonlinear Observer ◽  
Navigation Systems ◽  
Level Control ◽  
Remotely Operated Vehicle ◽  
Low Level ◽  
Level Control System ◽  
High Level ◽  
And Control

This paper addresses the development of the simulation of the low-level control system for the underwater remotely operated vehicle Visor3. The 6-DOF mathematical model of Visor3 is presented using two coordinated systems: Earth-fixed and body-fixed frames. The navigation, guidance, and control (NGC) structure is divided into three layers: the high level or the mission planner; the mid-level or the path planner; and the low level formed by the navigation and control systems. The nonlinear model-based observer is developed using the extended Kalman filter (EKF) which uses the linearization of the model to estimate the current state. The behavior of the observer is verified through simulations using Simulink®. An experiment was conducted with a trajectory that describes changes in the x and y and yaw components. To accomplish this task, two algorithms are compared: a multiloop PID and PID with gravity compensation. These controllers and the nonlinear observer are tested using the 6-DOF mathematical model of Visor3. The control and navigation systems are a fundamental part of the low-level control system that will allow Visor3’s operators to take advantage of more advanced vehicle’s capabilities during inspection tasks of port facilities, hydroelectric dams, and oceanographic research.

RT-Mover: a rough terrain mobile robot with a simple leg–wheel hybrid mechanism

2011 ◽  
Vol 30 (13) ◽  
pp. 1609-1626 ◽  
Author(s):  
Shuro Nakajima
Keyword(s):  
Mobile Robot ◽  
Mechanical Design ◽  
Design Concept ◽  
Rough Terrain ◽  
Personal Mobility ◽  
Mobility Performance ◽  
Stability And Control ◽  
Horizontal Orientation ◽  
Hybrid Mechanism ◽  
And Control

There is a strong demand in many fields for practical robots, such as a porter robot and a personal mobility robot, that can move over rough terrain while carrying a load horizontally. We have developed a robot, called RT-Mover, which shows adequate mobility performance on targeted types of rough terrain. It has four drivable wheels and two leg-like axles but only five active shafts. A strength of this robot is that it realizes both a leg mode and a wheel mode in a simple mechanism. In this paper, the mechanical design concept is discussed. With an emphasis on minimizing the number of drive shafts, a mechanism is designed for a four-wheeled mobile body that is widely used in practical locomotive machinery. Also, strategies for moving on rough terrain are proposed. The kinematics, stability, and control of RT-Mover are also described in detail. Some typical cases of rough terrain for wheel mode and leg mode are selected, and the robot’s ability of locomotion is assessed through simulations and experiments. In each case, the robot is able to move over rough terrain while maintaining the horizontal orientation of its platform.

Buckybot: A Robot Based on the Geometry of a Truncated Icosahedron

2014 ◽  
Author(s):  
Michael D. M. Kutzer ◽  
Christopher Y. Brown ◽  
Gregory S. Chirikjian ◽  
Mehran Armand
Keyword(s):  
Mobile Robot ◽  
Trajectory Planning ◽  
Mobile Platform ◽  
Control Algorithms ◽  
Level Control ◽  
Soccer Ball ◽  
Low Level ◽  
Symmetric Geometry

This paper introduces Buckybot, a novel mobile platform, and investigates its kinematics and preliminary control algorithms. Buckybot is a ground-based platform whose geometry is based on a truncated icosahedron, i.e. a soccer ball with flattened sides. The platform has 20 passive hexagonal faces on which it can stably rest, and 12 rounded pentagonal faces which can be extended linearly to tilt Buckybot. The symmetric geometry of the robot makes it operational in any configuration which is ideal for a variety of deployment scenarios including throwing or dropping. Buckybot currently locomotes using a semi-static tipping gait to move between adjacent hexagonal faces. In this work, we present the design and low-level control of the Buckybot platform, explore the kinematics associated with Buckybot’s method of locomotion, experimentally characterize tipping, and investigate trajectory planning for this new mobile robot. Results demonstrate effective trajectory planning accounting for plan uncertainty.

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