Joint Impedance Pneumatic Control for Multilink Systems

1999 ◽  
Vol 121 (2) ◽  
pp. 293-297 ◽  
Author(s):  
P. Gorce ◽  
M. Guihard
Keyword(s):  
Biped Robot ◽  
Legged Robots ◽  
Continuous Control ◽  
Nonlinear Controller ◽  
Control Laws ◽  
Pneumatic Control ◽  
Dynamic Tracking ◽  
Mechanical Models ◽  
Good Behaviour ◽  
Computed Torque

In this paper, we propose a general controller for complex tasks such as coordination or manipulation for grasping systems or dynamic gaits for legged robots. Moreover, this controller is adapted to pneumatic actuated structures. The aim is then to ensure a dynamic tracking of position and force for systems which may interact with the environment or cooperate with each other. For that, we propose a nonlinear controller based on a computed torque method taking into account the actuator and the mechanical models. The originality lays in the consideration of impedance behaviour at each joint during free and constrained tasks. It leads to continuous control laws between contact and non-contact phases. The asymptotic stability is ensured using Popov criteria. The application proposed is the control of one pneumatic leg of a biped robot. We present a dynamic model of the leg and chosen trajectories. Simulation results of this new controller are presented, leading to a good behaviour of the leg during a whole walking cycle at relatively high velocities.

Simulation of a dynamic vertical jump

Robotica ◽  
2001 ◽  
Vol 19 (1) ◽  
pp. 87-91 ◽  
Author(s):  
M. Guihard ◽  
P. Gorce
Keyword(s):  
Controller Design ◽  
Vertical Jump ◽  
Rigid Bodies ◽  
Pneumatic Actuator ◽  
Dynamic Effects ◽  
Complex Motion ◽  
Control Laws ◽  
Dynamic Tracking ◽  
High Acceleration ◽  
Mechanical Models

The aim of this paper is to propose a bipedal structure able to follow high acceleration movements. The vertical jump of a human has been chosen as input (coming from experiments) to validate the controller design as it is one of the most complex motion. The study concerns the low level of the biped control that is to say the control design of one leg made of three rigid bodies, each of them moved by a pneumatic actuator. An analogy between a pneumatic actuator and a physiological muscle is first proposed. A dynamic model of the leg is then presented decoupling the dynamic effects of the skeletal (as interactions between segments) from the dynamic effects of the muscles involved. The controller is based on the nonlinear theory (taking into account the actuator and the mechanical models), it ensures a dynamic tracking of position and force. Its originality lays in the consideration of impedance behaviour at each joint during free and constrained tasks. It leads to asymptotically stable (Popov criteria) control laws which are continuous between contact and non-contact phases enabling real-time computations. The simulation results clearly show the tracking of position and forces during the whole jump cycle.

Heuristic control of bipedal running: steady-state and accelerated

Robotica ◽  
2011 ◽  
Vol 29 (6) ◽  
pp. 939-947
Author(s):  
A. D. Perkins ◽  
K. J. Waldron ◽  
P. J. Csonka
Keyword(s):  
Steady State ◽  
Experimental System ◽  
Legged Robots ◽  
Stable Steady State ◽  
Control Laws ◽  
Mechanical Coupling ◽  
Ankle Joints

SUMMARYThe design, control, and actuation of legged robots that walk is well established, but there remain unsolved problems for legged robots that run. In this work, dynamic principles are used to develop a set of heuristics for controlling bipedal running and acceleration. These heuristics are then converted into control laws for two very different bipedal systems: one with a high-inertia torso and prismatic knees and one with a low-inertia torso, articulated knees, and mechanical coupling between the knee and ankle joints. These control laws are implemented in simulation to achieve stable steady-state running, accelerating, and decelerating. Stable steady-state running is also achieved in a planar experimental system with a semiconstrained torso.

Identification of Postural Controllers in Human Standing Balance

2020 ◽  
Vol 143 (4) ◽  
Author(s):  
Huawei Wang ◽  
Antonie J. van den Bogert
Keyword(s):  
Trajectory Optimization ◽  
Standing Balance ◽  
Multiple Time ◽  
Nonlinear Controller ◽  
Control Laws ◽  
Motion Data ◽  
Nonlinear Properties ◽  
Balance System ◽  
Healthy Humans ◽  
Balance Task

Abstract Standing balance is a simple motion task for healthy humans but the actions of the central nervous system (CNS) have not been described by generalized and sufficiently sophisticated control laws. While system identification approaches have been used to extracted models of the CNS, they either focus on short balance motions, leading to task-specific control laws, or assume that the standing balance system is linear. To obtain comprehensive control laws for human standing balance, complex balance motions, long duration tests, and nonlinear controller models are all needed. In this paper, we demonstrate that trajectory optimization with the direct collocation method can achieve these goals to identify complex CNS models for the human standing balance task. We first examined this identification method using synthetic motion data and showed that correct control parameters can be extracted. Then, six types of controllers, from simple linear to complex nonlinear, were identified from 100 s of motion data from randomly perturbed standing. Results showed that multiple time-delay paths and nonlinear properties are both needed in order to fully explain human feedback control of standing balance.

scholarly journals Synthesis of intelligent fuzzy control in the space of bounded piecewise-continuous functions based on the combined maximum principle

2018 ◽  
Vol 226 ◽  
pp. 04031 ◽  
Author(s):  
Andrey A. Kostoglotov ◽  
Sergey V. Lazarnko ◽  
Igor A. Nikitin
Keyword(s):  
Control Method ◽  
Control Object ◽  
Continuous Functions ◽  
Terminal State ◽  
Control Synthesis ◽  
Continuous Control ◽  
Control Laws ◽  
Relay Control ◽  
Piecewise Continuous ◽  
Two Stages

It is shown that the solution of the problem of control synthesis using the Hamilton-Ostrogradskii principle leads to a variational inequality, from which the conditions for the maximum of the the generalized power function in the space of bounded piecewise continuous functions follow. It allows to find a feedback structure up to a synthesis function. Using the methods of the structure construction the nonlinear structures of the relay and continuous control laws are obtained. The proposed control method allows to avoid the mode with frequented switching. It consists of the following two stages. At the first stage, the control object is brought into the vicinity of the terminal state using the relay control law. In the second stage, the quasi-optimal continuous control is used. The uncertainty of the transition area size is resolved using fuzzy logic. The efficiency of the intelligent controls is demonstrated by the example of mathematical modeling of the system dynamics.

A Unidirectional Series-Elastic Actuator Design Using a Spiral Torsion Spring

2009 ◽  
Vol 131 (12) ◽  
Author(s):  
Brian T. Knox ◽  
James P. Schmiedeler
Keyword(s):  
Position Control ◽  
Biped Robot ◽  
Legged Robots ◽  
Torsion Spring ◽  
Series Elastic Actuator ◽  
Electromechanical Actuation ◽  
Torsion Springs ◽  
Actuator Design ◽  
Rotational Direction ◽  
Series Elastic

This paper presents a novel series-elastic actuator (SEA) design that uses a spiral torsion spring to achieve drivetrain compliance in a compact and efficient mechanism. The SEA utilizes electromechanical actuation and is designed for use in the experimental biped robot KURMET for investigating dynamic maneuvers. Similar to helical torsion springs, spiral torsion springs are particularly applicable for legged robots because they preserve the rotational motion inherent in electric motors and articulated leg joints, but with less drivetrain backlash and unwanted coil interaction under load than helical torsion springs. The general spiral torsion spring design equations are presented in a form convenient for robot design, along with a detailed discussion of the mechanism surrounding the spring. Also, the SEA mechanism has a set of unidirectional hardstops that further improves the position control by allowing series-elasticity in only one rotational direction.

Nonlinear Control of Variable Speed Wind Turbines With Switching Across Operating Regimes

2011 ◽  
Author(s):  
Tuhin Das ◽  
Greg Semrau ◽  
Sigitas Rimkus
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Equilibrium Points ◽  
Control Input ◽  
Variable Speed ◽  
Nonlinear Controller ◽  
Wind Speed Profile ◽  
Control Laws ◽  
Wind Speeds ◽  
Operating Regimes

One of the key control problems associated with variable speed wind turbine systems is maximization of energy extraction when operating below the rated wind speed and power regulation when operating above the rated wind speed. In this paper, we approach these problems from a nonlinear systems perspective. For below rated wind speeds we adopt existing work appearing in the literature and provide further insight into the characteristics of the resulting equilibrium points of the closed-loop system. For above rated wind speeds, we propose a nonlinear controller and analyze the stability property of the resulting equilibria. We also propose a method for switching between the two operating regimes that ensures continuity of control input at the transition point. The control laws are verified using a wind turbine model with a standard turbulent wind speed profile that spans both operating regimes.

scholarly journals A Novel Family of Exact Nonlinear Cascade Control Design Solutions for a Class of UAV Systems

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Kristian Maya-Gress ◽  
Jorge Álvarez ◽  
Raúl Villafuerte-Segura ◽  
Hugo Romero-Trejo ◽  
Miguel Bernal
Keyword(s):  
Control Design ◽  
Cascade Control ◽  
Second Step ◽  
Control Laws ◽  
Control Scheme ◽  
Cascade Structure ◽  
Vehicle Position ◽  
Angular Coordinates ◽  
Double Integrator ◽  
Computed Torque

In this work, a novel family of exact nonlinear control laws is developed for trajectory tracking of unmanned aerial vehicles. The proposed methodology exploits the cascade structure of the dynamic equations of most of these systems. In a first step, the vehicle position in Cartesian coordinates is controlled by means of fictitious inputs corresponding to the angular coordinates, which are fixed to a combination of computed torque and proportional-derivative elements. In a second step, the angular coordinates are controlled as to drive them to the desired fictitious inputs necessary for the first part, resulting in a double-integrator 3-input cascade control scheme. The proposal is put at test in two examples: 4-rotor and 8-rotor aircrafts. Numerical simulations of both plants illustrate the effectiveness of the proposed method, while real-time results of the first one confirm its applicability.

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