Design and analysis of an active gimbal simulator with three degrees-of-freedom for ground testing

2018 ◽  
Vol 233 (7) ◽  
pp. 2552-2562
Author(s):  
Jiao Jia ◽  
Yingmin Jia ◽  
Shihao Sun
Keyword(s):  
Degrees Of Freedom ◽  
Attitude Determination ◽  
Contact Forces ◽  
Design Parameters ◽  
Force Analysis ◽  
Ground Testing ◽  
Neutral Equilibrium ◽  
Main Support ◽  
And Control ◽  
Three Degrees Of Freedom

In this paper, a new active gimbal simulator is developed for testing the attitude determination and control system of satellites. The active gimbal simulator is composed of a rolling joint, a pitching joint, a main support frame, an active yawing joint, and a fixture. The rolling joint enables the active gimbal simulator to be applied to the columnar satellite without the fixture. The contact forces between the rolling joint and the test satellite (or the fixture) can be regulated by the support of the pitching joint. The object attached to the active gimbal simulator is at neutral equilibrium and can maintain balance at an arbitrary attitude. Hence, the object can rotate freely without being affected by its gravity. The active gimbal simulator is an approximately free-to-free suspension or support method. Compared with the traditional gimbals, the active gimbal simulator can be applied to objects of arbitrary shape especially cylinders and the effect of exogenous mass and inertia introduced by the connection mechanism is reduced. The design parameters of the active gimbal simulator are optimized based on the force analysis. A specific prototype was made, and its feasibility was verified by laboratory-based experiments.

Architecture Optmization of a 3-DOF Parallel Mechanism

1998 ◽  
Author(s):  
J. A. Carretero ◽  
R. P. Podhorodeski ◽  
M. Nahon
Keyword(s):  
Parallel Mechanism ◽  
Architectural Design ◽  
Degrees Of Freedom ◽  
Jacobian Matrix ◽  
Design Parameters ◽  
Objective Functions ◽  
Constraint Equations ◽  
Three Degree Of Freedom ◽  
Architecture Optimization ◽  
Three Degrees Of Freedom

Abstract This paper presents a study of the architecture optimization of a three-degree-of-freedom parallel mechanism intended for use as a telescope mirror focussing device. The construction of the mechanism is first described. Since the mechanism has only three degrees of freedom, constraint equations describing the inter-relationship between the six Cartesian coordinates are given. These constraints allow us to define the parasitic motions and, if incorporated into the kinematics model, a constrained Jacobian matrix can be obtained. This Jacobian matrix is then used to define a dexterity measure. The parasitic motions and dexterity are then used as objective functions for the optimizations routines and from which the optimal architectural design parameters are obtained.

Simulation of Helicopter Powerplant Performance

1978 ◽  
Author(s):  
B. V. Baxendale ◽  
M. E. Inglis
Keyword(s):  
Power Plants ◽  
Degrees Of Freedom ◽  
Vertical Plane ◽  
System Failure ◽  
Flight Data ◽  
Rotor Systems ◽  
Hybrid Computer ◽  
And Control ◽  
Three Degrees Of Freedom ◽  
Proper Account

Programs have been written for a hybrid computer to simulate in real time the dynamic behavior of the engines, airframe, and rotor systems of the Sea King and Lynx helicopters; their purpose is to aid the study of performance and control of helicopter power plants. Since the engines are directly coupled to the lift-producing surface (the rotor), it is important to take proper account of the interactions between the power plant and the rest of the aircraft; however, for this type of work, it is reasonable to limit simulated aircraft maneuvers to three degrees of freedom in a single vertical plane. The method of simulating the major features of the helicopter are discussed, along with their implementation on the hybrid computer. The paper goes on to describe the successful validation of the two models by comparison with specially obtained flight data on a range of rapid maneuvers involving large changes in power demands. Finally, a description is given of an exercise on the Sea King simulation to investigate the effect of an engine or control system failure at a critical flight condition.

Wheel-Based Stair Climbing Robot with Hopping Mechanism – Demonstration of Continuous Stair Climbing Using Vibration –

2008 ◽  
Vol 20 (2) ◽  
pp. 221-227 ◽  
Author(s):  
Yuji Asai ◽  
◽  
Yasuhiro Chiba ◽  
Keisuke Sakaguchi ◽  
Naoki Bushida ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Mechanical Design ◽  
Stair Climbing ◽  
Design Parameters ◽  
Mass Ratio ◽  
Climbing Robot ◽  
Soft Landing ◽  
Hopping Mechanism ◽  
And Control ◽  
Two Bodies

We propose a simple hopping mechanism using vibration of a two-degrees-of-freedom (2-DOF) system for a fast stair-climbing robot. The robot, consisting of two bodies connected by springs and a wire, hops by releasing energy stored in springs and travels quickly using wheels mounted on its lower body. The trajectories of bodies during hopping change based on mechanical design parameters such as reduced mass of the two bodies, the mass ratio between the upper and lower bodies, and spring constant, and control parameters such as initial contraction of the spring and wire tension. This property allows the robot to quickly and economically climb stairs and land softly without complex control. In this paper, we propose a mathematical model of the robot and investigate required tread length for continuous hopping to climb a flight of stairs. Furthermore, we demonstrate fast stair-climbing and soft landing for a flight of stairs in experiments.

Influences of Arm Proprioception and Degrees of Freedom on Postural Control With Light Touch Feedback

2008 ◽  
Vol 99 (2) ◽  
pp. 595-604 ◽  
Author(s):  
Ely Rabin ◽  
Paul DiZio ◽  
Joel Ventura ◽  
James R. Lackner
Keyword(s):  
Postural Control ◽  
Degrees Of Freedom ◽  
Biceps Brachii ◽  
Postural Sway ◽  
Center Of Pressure ◽  
Tactile Feedback ◽  
Contact Forces ◽  
Light Touch ◽  
Postural Stabilization ◽  
And Control

Lightly touching a stable surface with one fingertip strongly stabilizes standing posture. The three main features of this phenomenon are fingertip contact forces maintained at levels too low to provide mechanical support, attenuation of postural sway relative to conditions without fingertip touch, and center of pressure (CP) lags changes in fingertip shear forces by ∼250 ms. In the experiments presented here, we tested whether accurate arm proprioception and also whether the precision fingertip contact afforded by the arm's many degrees of freedom are necessary for postural stabilization by finger contact. In our first experiment, we perturbed arm proprioception and control with biceps brachii vibration (120-Hz, 2-mm amplitude). This degraded postural control, resulting in greater postural sway amplitudes. In a second study, we immobilized the touching arm with a splint. This prevented precision fingertip contact but had no effect on postural sway amplitude. In both experiments, the correlation and latency of fingertip contact forces to postural sway were unaffected. We conclude that postural control is executed based on information about arm orientation as well as tactile feedback from light touch, although precision fingertip contact is not essential. The consistent correlation and timing of CP movement and fingertip forces across conditions in which postural sway amplitude and fingertip contact are differentially disrupted suggests posture and the fingertip are controlled in parallel with feedback from the fingertip in this task.

scholarly journals Wheel-Based Stair Climbing Robot with Hopping Mechanism - Fast Stair Climbing and Soft Landing Using Vibration of 2-DOF System -

2007 ◽  
Vol 19 (3) ◽  
pp. 258-263 ◽  
Author(s):  
Keisuke Sakaguchi ◽  
◽  
Takayuki Sudo ◽  
Naoki Bushida ◽  
Yasuhiro Chiba ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Stair Climbing ◽  
Design Parameters ◽  
Control Parameters ◽  
Mass Ratio ◽  
Climbing Robot ◽  
Soft Landing ◽  
Hopping Mechanism ◽  
And Control ◽  
Two Bodies

We propose a simple hopping mechanism using the vibration of a two-degrees-of-freedom (DOF) system for a fast stair-climbing robot. The robot, consisting of two bodies connected by springs, hops by releasing energy stored in springs and travels quickly using wheels mounted on its lower body. The trajectories of bodies during hopping change based on design parameters such as the reduced mass of the two bodies, mass ratio between the upper and lower bodies, spring constant, and control parameters such as initial contraction of the spring and wire tension. This property allows the robot to quickly and economically climb stairs and land softly. In this paper, the characteristics of hopping for the design and control parameters are clarified by both numerical simulation and experiments. Furthermore, fast stair climbing and soft landing are demonstrated.

Optimal grasp force for robotic grasping and in-hand manipulation with impedance control

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Xiaoqing Li ◽  
Ziyu Chen ◽  
Chao Ma
Keyword(s):  
Degrees Of Freedom ◽  
Impedance Control ◽  
Difficult Problem ◽  
Contact Forces ◽  
Design Parameters ◽  
Robotic Hand ◽  
Content Type ◽  
Cone Constraint ◽  
Grasp Force ◽  
Grasp Quality

Purpose The purpose of this paper is to achieve stable grasping and dexterous in-hand manipulation, the control of the multi-fingered robotic hand is a difficult problem as the hand has many degrees of freedom with various grasp configurations. Design/methodology/approach To achieve this goal, a novel object-level impedance control framework with optimized grasp force and grasp quality is proposed for multi-fingered robotic hand grasping and in-hand manipulation. The minimal grasp force optimization aims to achieve stable grasping satisfying friction cone constraint while keeping appropriate contact forces without damage to the object. With the optimized grasp quality function, optimal grasp quality can be obtained by dynamically sliding on the object from initial grasp configuration to final grasp configuration. By the proposed controller, the in-hand manipulation of the grasped object can be achieved with compliance to the environment force. The control performance of the closed-loop robotic system is guaranteed by appropriately choosing the design parameters as proved by a Lyapunove function. Findings Simulations are conducted to validate the efficiency and performance of the proposed controller with a three-fingered robotic hand. Originality/value This paper presents a method for robotic optimal grasping and in-hand manipulation with a compliant controller. It may inspire other related researchers and has great potential for practical usage in a widespread of robot applications.

Robust Trajectory Following Control of Robotic Systems

1985 ◽  
Vol 107 (4) ◽  
pp. 308-315 ◽  
Author(s):  
S. N. Singh ◽  
A. A. Schy
Keyword(s):  
Degrees Of Freedom ◽  
Digital Simulation ◽  
Robotic Systems ◽  
Control Law ◽  
Robot Arm ◽  
Control Laws ◽  
Payload Uncertainty ◽  
Trajectory Following ◽  
And Control ◽  
Three Degrees Of Freedom

Using an inversion approach we derive a control law for trajectory following of robotic systems. A servocompensator is used around the inner decoupled loop for robustness to uncertainty in the system. These results are applied to trajectory control of a three-degrees-of-freedom robot arm and control laws Cθ and CH for joint angle and position trajectory following, respectively, are derived. Digital simulation results are presented to show the rapid trajectory following capability of the controller in spite of payload uncertainty.

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