Linkage-Based Analysis and Optimization of an Underactuated Planar Manipulator for In-Hand Manipulation

2013 ◽  
Vol 6 (1) ◽  
Author(s):  
Raymond R. Ma ◽  
Aaron M. Dollar
Keyword(s):  
Energy Minimization ◽  
Degrees Of Freedom ◽  
Design Space ◽  
Joint Stiffness ◽  
Robotic Hand ◽  
Linkage Mechanism ◽  
Compliant Joints ◽  
Underactuated Manipulator ◽  
Underactuated Manipulators ◽  
Ratio Transmission

This paper investigates the in-hand manipulation capabilities of a compliant, underactuated planar robotic hand by treating the system as a simple, symmetric, 6-bar linkage mechanism with compliant joints. Although underactuated hands are generally not considered to be adept at dexterous tasks, we have found through past work that an underactuated manipulator can control n degrees of freedom with n actuators by leveraging the passive compliance to satisfy contact constraints on the object. Assuming the system to be quasi-static, the workspace of the underactuated mechanism is found through constraint-based energy minimization by sweeping through the set of allowable inputs. In this study, we investigate achievable workspaces by exploring the nondimensionalized design space, consisting of linkage ratio, joint stiffness ratio, transmission ratio, base linkage length, and object linkage length. The results of this study are useful in motivating the design of dexterous, underactuated manipulators, as well as to predict the achievable workspace of specific hand/object configurations.

Robust Joint and Cartesian Control of Underactuated Manipulators

1996 ◽  
Vol 118 (3) ◽  
pp. 557-565 ◽  
Author(s):  
Marcel Bergerman ◽  
Yangsheng Xu
Keyword(s):  
Degrees Of Freedom ◽  
Control Method ◽  
Variable Structure ◽  
Joint Space ◽  
Control Technique ◽  
Underactuated System ◽  
Underactuated Manipulator ◽  
Underactuated Manipulators ◽  
Compact Design ◽  
Weight Decrease

Underactuated manipulators are robot manipulators composed of both active and passive joints in serial chain mechanisms. The study of underactuation is significant for the control of a variety of rigid-body systems, such as free-floating robots in space and gymnasts, whose structure include passive joints. For mechanisms with large degrees of freedom, such as hyper-redundant snake-like robots and multi-legged machines, the underactuated structure allows a more compact design, weight decrease, and energy saving. Furthermore, when one or more joints of a standard manipulator fail, it becomes an underactuated mechanism; a control technique for such system will increase the reliability and fault-tolerance of current and future robots. The goal of this study is to present a robust control method for the control of underactuated manipulators subject to modeling errors and disturbances. Because an accurate modelling of the underactuated system is more critical for control issues than it is for standard manipulators, this method is significant in practice. Variable structure controllers are proposed in both joint space and Cartesian space, and a comprehensive simulation study is presented to address issues such as computation, robustness, and feasibility of the methods. Experimental results demonstrate the actual applicability of the proposed methods in a real two-degrees-of-freedom underactuated manipulator. As it will be shown, the proposed variable structure controller provides robustness againstboth disturbances and parametric uncertainties, a characteristic not present on previously proposed PID-based schemes.

Experimental Validation of the Kinematics of a 3PRS Compliant Mechanism for Micromilling

2015 ◽  
Author(s):  
Antonio Ruiz ◽  
Francisco Campa Gomez ◽  
Constantino Roldan-Paraponiaris ◽  
Oscar Altuzarra
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Experimental Validation ◽  
Compliant Mechanism ◽  
Motion Controller ◽  
End Effector ◽  
Compliant Joints ◽  
Hybrid Manipulator ◽  
Compliant Parallel Mechanism ◽  
Actuated Joints

The present work deals with the development of a hybrid manipulator of 5 degrees of freedom for milling moulds for microlenses. The manipulator is based on a XY stage under a 3PRS compliant parallel mechanism. The mechanism takes advantage of the compliant joints to achieve higher repetitiveness, smoother motion and a higher bandwidth, due to the high precision demanded from the process, under 0.1 micrometers. This work is focused on the kinematics of the compliant stage of the hybrid manipulator. First, an analysis of the workspace required for the milling of a single mould has been performed, calculating the displacements required in X, Y, Z axis as well as two relative rotations between the tool and the workpiece from a programmed toolpath. Then, the 3PRS compliant parallel mechanism has been designed using FEM with the objective of being stiff enough to support the cutting forces from the micromilling, but flexible enough in the revolution and spherical compliant joints to provide the displacements needed. Finally, a prototype of the 3PRS compliant mechanism has been built, implementing a motion controller to perform translations in Z direction and two rotations. The resulting displacements in the end effector and the actuated joints have been measured and compared with the FEM calculations and with the rigid body kinematics of the 3PRS.

Performance Oriented Design of Semiregular Anisotropic Porous Structures

2018 ◽  
Author(s):  
Chao Xu ◽  
Lili Pan ◽  
Ming Li ◽  
Shuming Gao
Keyword(s):  
3D Printing ◽  
Porous Materials ◽  
Design Problem ◽  
Degrees Of Freedom ◽  
Design Space ◽  
Manufacturing Technology ◽  
Porous Structures ◽  
Precise Control ◽  
And Performance

Porous materials / structures have wide applications in industry, since the sizes, shapes and positions of their pores can be adjusted on various demands. However, the precise control and performance oriented design of porous structures are still urgent and challenging, especially when the manufacturing technology is well developed due to 3D printing. In this study, the control and design of anisotropic porous structures are studied with more degrees of freedom than isotropic structures, and can achieve more complex mechanical goals. The proposed approach introduces Super Formula to represent the structural cells, maps the design problem to an optimal problem using PGD, and solves the optimal problem using MMA to obtain the structure with desired performance. The proposed approach is also tested on the performance of the expansion of design space, the capture of the physical orientation and so on.

Miniaturized Pneumatic Artificial Muscles Actuating a Bio-Inspired Robot Hand

2013 ◽  
Author(s):  
Thomas E. Pillsbury ◽  
Ryan M. Robinson ◽  
Norman M. Wereley
Keyword(s):  
Degrees Of Freedom ◽  
Full Scale ◽  
Constitutive Relationship ◽  
Force Density ◽  
Human Hand ◽  
Artificial Muscles ◽  
Specific Work ◽  
Robotic Hand ◽  
Robot Hand ◽  
Pneumatic Artificial Muscles

Pneumatic artificial muscles (PAMs) are used in robotics applications for their light-weight design and superior static performance. Additional PAM benefits are high specific work, high force density, simple design, and long fatigue life. Previous use of PAMs in robotics research has focused on using “large,” full-scale PAMs as actuators. Large PAMs work well for applications with large working volumes that require high force and torque outputs, such as robotic arms. However, in the case of a compact robotic hand, a large number of degrees of freedom are required. A human hand has 35 muscles, so for similar functionality, a robot hand needs a similar number of actuators that must fit in a small volume. Therefore, using full scale PAMs to actuate a robot hand requires a large volume which for robotics and prosthetics applications is not feasible, and smaller actuators, such as miniature PAMs, must be used. In order to develop a miniature PAM capable of producing the forces and contractions needed in a robotic hand, different braid and bladder material combinations were characterized to determine the load stroke profiles. Through this characterization, miniature PAMs were shown to have comparably high force density with the benefit of reduced actuator volume when compared to full scale PAMs. Testing also showed that braid-bladder interactions have an important effect at this scale, which cannot be modeled sufficiently using existing methods without resorting to a higher-order constitutive relationship. Due to the model inaccuracies and the limited selection of commercially available materials at this scale, custom molded bladders were created. PAMs created with these thin, soft bladders exhibited greatly improved performance.

HYBRID CLASSIFICATION STRATEGY OF EMG SIGNALS FOR ROBOTIC HAND CONTROL

2021 ◽  
pp. 2150015
Author(s):  
Fazia sbargoud ◽  
Mohamed Djeha ◽  
Mohamed Guiatni ◽  
Noureddine Ababou
Keyword(s):  
Degrees Of Freedom ◽  
Wavelet Packet ◽  
Hybrid Approach ◽  
Human Motion ◽  
Robotic Hand ◽  
User Intention ◽  
Emg Signal ◽  
Hybrid Classification ◽  
Electromyographic Signal ◽  
Artificial Neural Network Ann

Among the different bio-signals modalities, Electromyographic signal (EMG) has been one of the frequently used signals in the bio-robotics applications field. This is due to the fact that the EMG reflects directly the muscle activity of the user following the human motion intention. Consequently, the decoding of this intention is an essential task for controlling devices such as prosthetic hands and exoskeletons, based on EMG signals. This paper deals with the processing of EMG signals of the forearm muscles, in order to control two degrees of freedom (2 DoFs) robotic hand. The main contribution of this paper is the proposal of a hybrid approach that combines a pattern and a non-pattern recognition-based strategy. The proposed approach aims to take advantage of both strategies and overcome their shortcomings leading to a better analysis of the user movement intention. The EMG recorded signals are processed for feature extraction based on a Wavelet Packet Decomposition (WPD) method and classification using an Artificial Neural Network (ANN). Furthermore, we investigate the effect of the various parameters such as the applied force level, the number of the EMG channels and the window length of the EMG signal. The proposed approach is validated experimentally under realistic conditions. Very interesting results have been obtained for user intention decoding.

Study of grasp-energy based optimal distribution of contact forces on a humanoid robotic hand during object grasp

Robotica ◽  
2021 ◽  
pp. 1-26
Author(s):  
Sourajit Mukherjee ◽  
Abhijit Mahapatra ◽  
Amit Kumar ◽  
Avik Chatterjee
Keyword(s):  
Optimization Algorithm ◽  
Degrees Of Freedom ◽  
Simulated Data ◽  
Performance Measure ◽  
Contact Forces ◽  
Contact Model ◽  
Robotic Hand ◽  
Net Energy ◽  
Optimal Distribution

Abstract A novel grasp optimization algorithm for minimizing the net energy utilized by a five-fingered humanoid robotic hand with twenty degrees of freedom for securing a precise grasp is presented in this study. The algorithm utilizes a compliant contact model with a nonlinear spring and damper system to compute the performance measure, called ‘Grasp Energy’. The measure, subject to constraints, has been minimized to obtain locally optimal cartesian trajectories for securing a grasp. A case study is taken to compare the analytical (applying the optimization algorithm) and the simulated data in MSC.Adams $^{^{\circledR}}$ , to prove the efficacy of the proposed formulation.

scholarly journals Virtualization of Robotic Hands Using Mobile Devices †

Robotics ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 81
Author(s):  
Santiago T. Puente ◽  
Lucía Más ◽  
Fernando Torres ◽  
and Francisco A. Candelas
Keyword(s):  
Degrees Of Freedom ◽  
Robotic Hand ◽  
Robot Hand ◽  
Real Time Control ◽  
Robotic Hands ◽  
Robot Operating System ◽  
Server Side ◽  
Time Control ◽  
Unity 3D ◽  
Real Robot

This article presents a multiplatform application for the tele-operation of a robot hand using virtualization in Unity 3D. This approach grants usability to users that need to control a robotic hand, allowing supervision in a collaborative way. This paper focuses on a user application designed for the 3D virtualization of a robotic hand and the tele-operation architecture. The designed system allows for the simulation of any robotic hand. It has been tested with the virtualization of the four-fingered Allegro Hand of SimLab with 16 degrees of freedom, and the Shadow hand with 24 degrees of freedom. The system allows for the control of the position of each finger by means of joint and Cartesian co-ordinates. All user control interfaces are designed using Unity 3D, such that a multiplatform philosophy is achieved. The server side allows the user application to connect to a ROS (Robot Operating System) server through a TCP/IP socket, to control a real hand or to share a simulation of it among several users. If a real robot hand is used, real-time control and feedback of all the joints of the hand is communicated to the set of users. Finally, the system has been tested with a set of users with satisfactory results.

scholarly journals Conceptual Design and Computational Modeling Analysis of a Single-Leg System of a Quadruped Bionic Horse Robot Driven by a Cam-Linkage Mechanism

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Liangwen Wang ◽  
Weiwei Zhang ◽  
Caidong Wang ◽  
Fannian Meng ◽  
Wenliao Du ◽  
...  
Keyword(s):  
Motion Analysis ◽  
Kinematic Analysis ◽  
Degrees Of Freedom ◽  
Structural Parameters ◽  
Three Dimensional ◽  
Kinematic Modeling ◽  
Linkage Mechanism ◽  
Vector Method ◽  
Pressure Angle ◽  
End Point

In this study, the configuration of a bionic horse robot for equine-assisted therapy is presented. A single-leg system with two degrees of freedom (DOFs) is driven by a cam-linkage mechanism, and it can adjust the span and height of the leg end-point trajectory. After a brief introduction on the quadruped bionic horse robot, the structure and working principle of a single-leg system are discussed in detail. Kinematic analysis of a single-leg system is conducted, and the relationships between the structural parameters and leg trajectory are obtained. On this basis, the pressure angle characteristics of the cam-linkage mechanism are studied, and the leg end-point trajectories of the robot are obtained for several inclination angles controlled by the rotation of the motor for the stride length adjusting. The closed-loop vector method is used for the kinematic analysis, and the motion analysis system is developed in MATLAB software. The motion analysis results are verified by a three-dimensional simulation model developed in Solidworks software. The presented research on the configuration, kinematic modeling, and pressure angle characteristics of the bionic horse robot lays the foundation for subsequent research on the practical application of the proposed bionic horse robot.

scholarly journals Design of a Two-DOFs Driving Mechanism for a Motion-Assisted Finger Exoskeleton

2020 ◽  
Vol 10 (7) ◽  
pp. 2619 ◽  
Author(s):  
Giuseppe Carbone ◽  
Eike Christian Gerding ◽  
Burkard Corves ◽  
Daniele Cafolla ◽  
Matteo Russo ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Experimental Tests ◽  
Design Solution ◽  
Driving Mechanism ◽  
Dimensional Synthesis ◽  
Linkage Mechanism ◽  
Healthy Human ◽  
Wide Range ◽  
Finger Motion ◽  
Human Finger

This paper presents a novel exoskeleton mechanism for finger motion assistance. The exoskeleton is designed as a serial 2-degrees-of-freedom wearable mechanism that is able to guide human finger motion. The design process starts by analyzing the motion of healthy human fingers by video motion tracking. The experimental data are used to obtain the kinematics of a human finger. Then, a graphic/geometric synthesis procedure is implemented for achieving the dimensional synthesis of the proposed novel 2 degrees of freedom linkage mechanism for the finger exoskeleton. The proposed linkage mechanism can drive the three finger phalanxes by using two independent actuators that are both installed on the back of the hand palm. A prototype is designed based on the proposed design by using additive manufacturing. Results of numerical simulations and experimental tests are reported and discussed to prove the feasibility and the operational effectiveness of the proposed design solution that can assist a wide range of finger motions with proper adaptability to a variety of human fingers.

Planar Manipulator with Mechanically Adjustable Joint Compliance

2012 ◽  
Vol 6 (1) ◽  
pp. 46-52 ◽  
Author(s):  
Hiroaki Seki ◽  
◽  
Yoshitsugu Kamiya ◽  
Masatoshi Hikizu
Keyword(s):  
Hollow Cylinder ◽  
Degrees Of Freedom ◽  
Joint Stiffness ◽  
Plane Motion ◽  
Leaf Spring ◽  
End Effector ◽  
Joint Compliance ◽  
Arbitrary Position ◽  
Joint Mechanism ◽  
Adjustable Compliance

A novel robot joint with mechanically adjustable compliance is presented. It utilizes a leaf spring and the joint compliance can be adjusted by rotating this spring, i.e., changing its bending direction. A joint actuatormoves an armlink via a connection that consists of a hollow cylinder and a leaf spring. This mechanism is compact to be installed in a joint and it can change the joint stiffness rapidly and stably. A planar manipulator using this joint mechanism is proposed for the contact or constraint tasks. Since four joints are necessary to obtain arbitrary stiffnesses and an arbitrary position of the end-effector in plane motion, a four DOF (degrees of freedom) manipulator with mechanically adjustable joint compliance is developed.

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