Posture Control Considering Joint Stiffness of a Robotic Arm Driven by Rubberless Artificial Muscle

2016 ◽  
Vol 10 (4) ◽  
pp. 503-510 ◽  
Author(s):  
Naoki Saito ◽  
◽  
Toshiyuki Satoh ◽  
Keyword(s):  
Joint Angle ◽  
Joint Stiffness ◽  
Mathematical Expression ◽  
Artificial Muscle ◽  
Good Control ◽  
Robotic Arm ◽  
Rubber Tube ◽  
Robotic Arms ◽  
Control Scheme ◽  
The Relationship

This paper describes a joint angle control considering the passive joint stiffness of robotic arms driven by rubberless artificial muscle (RLAM), which is a pneumatic actuator. The contraction mechanism of RLAM is the same as that of the McKibben artificial muscle. Unlike the McKibben artificial muscle, RLAM is constructed using an airbag made of a nonelastic material instead of a rubber tube.The objective of this study is to realize a soft contact movement of robotic arms by applying the passive compliance characteristics of RLAMs. In this study, we derive a mathematical expression for the relationship between the output of an RLAM and the joint stiffness of a robotic arm. In addition, we suggest a control scheme for each RLAM. We confirm the validity of these suggestions experimentally. From the result, we observe a good control performance of the joint angle. A robotic arm moves smoothly according to the force added from outside by setting the passive stiffness of the arm.

scholarly journals Development of an Exoskeleton-Type Assist Suit Utilizing Variable Stiffness Control Devices Based on Human Joint Characteristics

Actuators ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 17
Author(s):  
Seigo Kimura ◽  
Ryuji Suzuki ◽  
Katsuki Machida ◽  
Masashi Kashima ◽  
Manabu Okui ◽  
...  
Keyword(s):  
Joint Stiffness ◽  
Knee Extensor ◽  
Artificial Muscle ◽  
Variable Stiffness ◽  
Lower Limbs ◽  
Joint Characteristics ◽  
Standing Up ◽  
Maximum Decrease ◽  
Control Devices ◽  
The Relationship

In this paper, the prototype of the assistive suit for lower limbs was developed. The prototype was based on an assist method with joint stiffness and antagonized angle control. The assist method comprises a system consisting of a pneumatic artificial muscle and a pull spring, which changes the joint stiffness and the antagonized angle to correspond to the movement phase and aims at coordinated motion assistance with the wearer. First, the characteristics of the developed prototype were tested. It was confirmed that the measured value of the prototype followed the target value in the relationship between torque and angle. In addition, there was hysteresis in the measured value, but it did not affect the assist. Next, the evaluation of standing-up and gait assist by measuring electromyography (EMG) of the knee extensor muscle was conducted using the prototype. In all subjects, a decrease in EMG due to the assist was confirmed. In one subject, the maximum decrease rate at the peak of the EMG was about 50% for standing-up motion and about 75% for gait motion. From the results of these assist evaluations, the effectiveness of the assist method based on the joint stiffness and antagonistic angle control using the prototype was confirmed.

scholarly journals On the elastodynamics of a five-axis lightweight anthropomorphic robotic arm

2021 ◽  
Author(s):  
Guanglei Wu
Keyword(s):  
Sensitivity Analysis ◽  
Joint Stiffness ◽  
Robotic Arm ◽  
Response Analysis ◽  
Modeling And Analysis ◽  
Robotic Arms ◽  
Linear Elastic ◽  
Small Influence ◽  
Elastodynamic Modeling ◽  
Five Axis

This paper presents elastodynamic modeling and analysis for a five-axis lightweight robotic arm. Natural frequencies are derived and visualized within the dexterous workspace to show the overall performances and compare them to the frequencies when the robotics is with payload. The comparison shows that the payload has a relatively small influence to the first- and second-order frequencies. Sensitivity analysis is conducted, and the system's frequency is more sensitive to the second joint stiffness than the others. Moreover, observations from the displacement response analysis reveal that the robotics produces linear elastic displacements of the same level between the loaded and unloaded working modes but larger rotational deflections under the loaded working condition. The main contribution of this work lies in that a systematic approach of elastodynamic analysis for serial robotic manipulators is formulated, where the arm gravity and external load are taken into account to investigate the dynamic behaviors of the robotic arms, i.e., frequencies, sensitivity analysis, and displacement responses, under the loaded mode.

scholarly journals Low-Cost Automation for Gravity Compensation of Robotic Arm

2020 ◽  
Vol 10 (11) ◽  
pp. 3823
Author(s):  
William Montalvo ◽  
Juan Escobar-Naranjo ◽  
Carlos A. Garcia ◽  
Marcelo V. Garcia
Keyword(s):  
Low Cost ◽  
Industrial Applications ◽  
Robotic Arm ◽  
Raspberry Pi ◽  
Gravity Compensation ◽  
Pd Control ◽  
End Effector ◽  
Robotic Arms ◽  
Position Errors ◽  
Control Scheme

During the Industry 4.0 era, the open source-based robotic arms control applications have been developed, in which the control algorithms apply for movement precision in the trajectory tracking paths based on direct or reverse kinematics. Therefore, small errors in the joint positions can summarize in large position errors of the end-effector in the industrial activities. Besides the change of the end-effector position for a given variation of the set-point in manipulator joint positions depends on the manipulator configuration. This research proposes a control based on Proportional Derivative (PD) Control with gravity compensation to show the robustness of this control scheme in the robotic arm’s industrial applications. The control algorithm is developed using a low-cost board like Raspberry Pi (RPI) where the Robot Operating System (ROS) is installed. The novelty of this approach is the development of new functions in ROS to make the PD control with gravity compensation in low-cost systems. This platform brings a fast exchange of information between the Kuka™ youBot robotic arm and a graphical user’s interface that allows a transparent interaction between them.

Approximation of the Kinematics of Foot Joints by Using Passive Elastic Characteristics of Joint

2007 ◽  
Vol 342-343 ◽  
pp. 621-624
Author(s):  
Hyeon Ki Choi ◽  
Si Yeol Kim ◽  
Won Hak Cho
Keyword(s):  
Joint Angle ◽  
Reaction Force ◽  
Force Plate ◽  
Least Square Method ◽  
Least Square ◽  
Biomechanical Analysis ◽  
Clinical Evaluations ◽  
Foot Joints ◽  
The Relationship ◽  
Elastic Characteristics

We investigated the relationship between kinematic and kinetic characteristics of foot joints resisting ground reaction force (GRF). Passive elastic characteristics of joint were obtained from the experiment using three cameras and one force plate. The relationship between joint angle and moment was mathematically modeled by using least square method. The calculated ranges of motion were 7o for TM joint, 4o for TT joint and 20o for MP joint. With the model that relates joint angle and plantar pressure, we could get the kinematic data of the joints which are not available from conventional motion analysis. The model can be used not only for biomechanical analysis which simulates gait but also for the clinical evaluations.

Design Human-Robot Collaborative Lifting Task Using Optimization

2021 ◽  
Author(s):  
Asif Arefeen ◽  
Yujiang Xiang
Keyword(s):  
Degrees Of Freedom ◽  
Joint Angle ◽  
Joint Torque ◽  
Robotic Arm ◽  
Inverse Dynamic ◽  
Floating Base ◽  
Grasping Forces ◽  
Design Variables ◽  
Human Arm ◽  
Lifting Task

Abstract In this paper, an optimization-based dynamic modeling method is used for human-robot lifting motion prediction. The three-dimensional (3D) human arm model has 13 degrees of freedom (DOFs) and the 3D robotic arm (Sawyer robotic arm) has 10 DOFs. The human arm and robotic arm are built in Denavit-Hartenberg (DH) representation. In addition, the 3D box is modeled as a floating-base rigid body with 6 global DOFs. The interactions between human arm and box, and robot and box are modeled as a set of grasping forces which are treated as unknowns (design variables) in the optimization formulation. The inverse dynamic optimization is used to simulate the lifting motion where the summation of joint torque squares of human arm is minimized subjected to physical and task constraints. The design variables are control points of cubic B-splines of joint angle profiles of the human arm, robotic arm, and box, and the box grasping forces at each time point. A numerical example is simulated for huma-robot lifting with a 10 Kg box. The human and robotic arms’ joint angle, joint torque, and grasping force profiles are reported. These optimal outputs can be used as references to control the human-robot collaborative lifting task.

Multiple Inputs-Single Accumulated Output Mechanism for Soft Linear Actuators

2018 ◽  
Vol 11 (1) ◽  
Author(s):  
Kyeong Ho Cho ◽  
Ho Moon Kim ◽  
Youngeun Kim ◽  
Sang Yul Yang ◽  
Hyouk Ryeol Choi
Keyword(s):  
Artificial Muscle ◽  
Operating Mode ◽  
Robotic Arm ◽  
Soft Actuator ◽  
Wearable Robots ◽  
Working Principle ◽  
Linear Actuators ◽  
Soft Actuators ◽  
Muscle Actuators ◽  
Further Development

Soft linear actuators (SLAs) such as shape memory alloy (SMA) wires, pneumatic soft actuators, dielectric elastomer actuator, and twisted and coiled soft actuator (TCA) called artificial muscle actuators in general, have many advantages over the conventional actuators. SLAs can realize innovative robotic technologies like soft robots, wearable robots, and bionic arms in the future, but further development is still needed in real applications because most SLAs do not provide large displacement or force as needed. This paper presents a novel mechanism supplementing SLAs by accumulating the displacement of multiple SLAs. It adopts the principle of differential gears in reverse. Since the input units of the mechanism are extensible, more displacement can be accumulated by increasing the number of the input units as many as needed. The mechanism is basically used to accumulate displacements, but can be used to accumulate forces by changing its operating mode. This paper introduces the design and working principle of the mechanism and validates its operation experimentally. In addition, the mechanism is implemented on a robotic arm and its effectiveness is confirmed.

scholarly journals Establishing the relationship between an effective audit committee and infusion of a good control environment

2017 ◽  
Vol 13 (3) ◽  
pp. 52-58 ◽  
Author(s):  
Zandile Virtue Dlamini ◽  
Emmanuel Mutambara ◽  
Akwesi Assensoh-Kodua
Keyword(s):  
Audit Committee ◽  
Good Governance ◽  
Good Control ◽  
Working Environment ◽  
Audit Committees ◽  
Control Environment ◽  
Public And Private ◽  
Control Structures ◽  
Effective Performance ◽  
The Relationship

Audit Committees are a vital component of accountability and good governance for any serious organisation and have progressively been perceived as an integral part of modern control structures and control practices in both the public and private sectors. However, Audit Committees can only discharge such gigantic responsibilities in a conducive environment to provide its effective performance of certain key functions in the areas of oversight of risk management, reporting, and internal controls. Nonetheless, the enablement of such conducive environments has become a challenge to many Audit Committees. It is against this background that this study investigates the relationship between an effective audit committee and infusion of a good control environment. The study used structured and unstructured questions to investigate population comprising standing committee members and Audit Committee members. Thus this study made use of a mixed methodology to collect quantitative data as well as reviewing audit documents, such as, the Audit Committee Charter and minutes of meetings in order to ascertain the environment under which such august practices are performed. The outcome concludes that the Audit Committee which was selected for the study has the good working environment.

scholarly journals Gesture Control of Robotic Arm

2017 ◽  
Vol 7 (1) ◽  
pp. 1
Author(s):  
Dharshan Y. ◽  
Vivek S. ◽  
Saranya S. ◽  
Aarthi V.R. ◽  
Madhumathi T.
Keyword(s):  
Batch Process ◽  
Robotic Arm ◽  
Robotic Arms ◽  
Key Technology ◽  
Cleaning Robot ◽  
Gesture Control ◽  
Major Chemical

<div><p><em>Robots have become a key technology in various fields. Robotic arms are mostly remote controlled by buttons or panels and sometimes in batch process they are autonomous. The usage of panel boards or control sticks includes a lot of hardwiring and subject to malfunction.  It also induces some stress on the operators. Hence major chemical industries like cosmetic manufacturing, paint manufacturing and Biosynthesis laboratory etc., which deals with hazardous environment due to the chemicals and other bio substances, involve humans for the processing. The aim is to reduce the bulk of wiring in the robotic arms and reduce the effort and number of operators in controlling the robotic arm operations. To implement gestures into the process this would be a major breakthrough. This can also be used as pick &amp; place robot, a cleaning robot in chemical industries where a human does not need to directly involved in the process of cleaning the chemicals and also for coating underground tanks.</em></p></div>

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