scholarly journals Numerical and Experimental Validation of the Prototype of A Bio-Inspired Piping Inspection Robot

Robotics ◽  
2019 ◽  
Vol 8 (2) ◽  
pp. 32 ◽  
Author(s):  
Swaminath Venkateswaran ◽  
Damien Chablat ◽  
Frédéric Boyer
Keyword(s):  
Dry Friction ◽  
Experimental Validation ◽  
Closed Loop ◽  
Contact Forces ◽  
Force Model ◽  
Static Force ◽  
Force Analysis ◽  
Inspection Robot ◽  
Dc Motors ◽  
Inspection Robots

Piping inspection robots are of greater importance for industries such as nuclear, chemical and sewage. Mechanisms having closed loop or tree-like structures can be employed in such pipelines owing to their adaptable structures. A bio-inspired caterpillar type piping inspection robot was developed at Laboratoire des Sciences du Numérique de Nantes (LS2N), France. Using DC motors and leg mechanisms, the robot accomplishes the locomotion of a caterpillar in six-steps. With the help of Coulomb’s law of dry friction, a static force model was written and the contact forces between legs of robot and pipeline walls were determined. The actuator forces of the DC motors were then estimated under static phases for horizontal and vertical orientations of the pipeline. Experiments were then conducted on the prototype where the peak results of static force analysis for a given pipe diameter were set as threshold limits to attain static phases inside a test pipeline. The real-time actuator forces were estimated in experiments for similar orientations of the pipeline of static force models and they were found to be higher when compared to the numerical model.

scholarly journals Design and Analysis of a Tensegrity Mechanism for a Bio-Inspired Robot

2019 ◽  
Author(s):  
Swaminath Venkateswaran ◽  
Matthieu Furet ◽  
Damien Chablat ◽  
Philippe Wenger
Keyword(s):  
Design Parameters ◽  
Static Force ◽  
Force Analysis ◽  
Universal Joint ◽  
End Effector ◽  
Inspection Robot ◽  
Reconfigurable System ◽  
Workspace Analysis ◽  
Applied Forces ◽  
Inspection Robots

Abstract Piping inspection robots are of greater interests in industries such as nuclear, chemical and sewage. The design of such robots is highly challenging owing to factors such as locomotion inside pipes with varying diameters, cable management, and complex pipe bends (or) junctions. A rigid bio-inspired caterpillar type piping inspection robot was developed at LS2N, France. By introducing tensegrity mechanisms and four-bar wheel mechanisms, the design of this robot is modified into a reconfigurable system. The tensegrity mechanism employs a passive universal joint with three tension springs and three cables for actuation. The positioning of the end effector with respect to the base of the mechanism plays an important role in determining the maximum tilt angle (or) bending limit of the system. By workspace analysis of three case studies, the best solution is chosen which generates the maximum tilt. A static force analysis is then performed on the mechanism to determine its stability under the influences of preload. By the modification of design parameters, stable configurations are determined followed by which cable actuation of mechanism is analyzed for estimating applied forces.

scholarly journals Trajectory Planning for a 3-SPS-U Tensegrity Mechanism

2021 ◽  
Author(s):  
Swaminath Venkateswaran ◽  
Damien Chablat
Keyword(s):  
Pid Controller ◽  
Control Algorithm ◽  
Closed Loop ◽  
Test Bench ◽  
Inverse Kinematic ◽  
Universal Joint ◽  
Inverse Kinematic Problem ◽  
Inspection Robot ◽  
Dc Motors ◽  
Pass Through

Abstract This article presents the actuation strategy of a 2-DOF tensegrity type mechanism that employs three tension springs and a passive universal joint. This mechanism is proposed to be incorporated as an articulation unit for a piping inspection robot in order to overcome pipe bends and junctions. In the event of a junction, external actuations are required to allow the mechanism as well as the robot to follow a certain direction. Using DC-motors coupled with encoders, experiments are carried out on a test bench of the tensegrity mechanism. The actuation of the mobile platform is performed using cables that pass through each spring. By correlating the architecture to a 3-SPS-U parallel mechanism, the singularity-free workspace of the mechanism is analyzed to identify the tilt limits. A closed-loop PID controller is implemented using a microcomputer to perform a linear trajectory within the singularity-free workspace. The Inverse Kinematic Problem (IKP) is solved by passing input tilt angles to the controller. With the help of a force control algorithm, the experiments are carried out under no-load conditions for vertical and horizontal orientations of the mechanism. The error data of the joint positions and the motor torques are then interpreted for both orientations of the mechanism.

scholarly journals Static Force Analysis of a 3-DOF Robot for Spinal Vertebral Lamina Milling

Machines ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 29
Author(s):  
Shaodong Li ◽  
Peiyuan Gao ◽  
Hongjian Yu ◽  
Mingqi Chen
Keyword(s):  
Screw Theory ◽  
Kinematic Model ◽  
Force Model ◽  
Static Force ◽  
Force Analysis ◽  
Joint Force ◽  
Simulation Results ◽  
The Mathematical Model ◽  
Human Robot Collaboration

In order to realize robot-assisted spinal laminectomy surgery and meet the clinical needs of the robot workspace, including accuracy in human–robot collaboration, an asymmetrical 3-DOF spatial translational robot is proposed, which can realize spinal laminectomy in a fixed posture. First, based on the screw theory, the constraint screw system of the robot was established, and the degree of freedom was derived to verify the spatial translational ability of the robot. Then, a kinematic model of the robot was established, and a static force model of the robot was derived based on the kinematic model. The mathematical relationship between the external force and the joint force/torque was obtained, with the quality of all links considered in the model. Finally, we modeled the robot and imported it into ADAMS to obtain the static force simulation results of the 3D model. The force error was approximately 0.001 N and the torque error was approximately 0.0001 N∙m compared with the simulation results of the mathematical model, accounting for 1% of the joint force/torque, which is acceptable. The result also showed the correctness of the mathematical models, and provides a theoretical basis for motion control and human–robot collaboration.

A two-wheel load balance control strategy for an HVTL inspection robot based on second-order sliding-mode

2019 ◽  
Vol 46 (1) ◽  
pp. 83-92 ◽  
Author(s):  
Zhihang He ◽  
Wei Wang ◽  
Huaping Ruan ◽  
Yanzhang Yao ◽  
Xuelong Li ◽  
...  
Keyword(s):  
Load Balance ◽  
Sliding Mode ◽  
Balance Control ◽  
Traction Force ◽  
Front Wheel ◽  
Force Model ◽  
Wheel Slip ◽  
Content Type ◽  
Inspection Robot ◽  
Inspection Robots

Purpose Overhead high-voltage transmission line (HVTL) inspection robots are used to inspect the transmission lines and/or maintain the infrastructures of a power transmission grid. One of the most serious problems is that the load on the front wheel is much larger than that on the back one when the robot travels along a sloping earth wire. Thus, ongoing operation of the inspection robot mainly depends on the front wheel motor’s ability. This paper aims to extend continuous operation time of the HVTL inspection robots. Design/methodology/approach By introducing a traction force model, the authors have established a dynamic model of the robot with slip. The total load is evenly distributed to both wheels. According to the traction force model, the desired wheel slip is calculated to achieve the goal of load balance. A wheel slip controller was designed based on second-order sliding-mode control methodology. Findings This controller accomplishes the control objective, such that the actual wheel slip tracks the desired wheel slip. A simulation and experiment verify the feasibility of the load balance control system. These results indicate that the loads on both wheels are generally equal. Originality/value By balancing the loads on both wheels, the inspection robot can travel along the earth wire longer, improving its efficiency.

scholarly journals Design and Calibration of a Force/Tactile Sensor for Dexterous Manipulation

Sensors ◽  
2019 ◽  
Vol 19 (4) ◽  
pp. 966 ◽  
Author(s):  
Marco Costanzo ◽  
Giuseppe De Maria ◽  
Ciro Natale ◽  
Salvatore Pirozzi
Keyword(s):  
Experimental Validation ◽  
Sensory System ◽  
Tactile Sensor ◽  
Contact Forces ◽  
Dexterous Manipulation ◽  
Soft Contact ◽  
Grasping Force ◽  
Sense Of Touch ◽  
Human Sense ◽  
Robotic Applications

This paper presents the design and calibration of a new force/tactile sensor for robotic applications. The sensor is suitably designed to provide the robotic grasping device with a sensory system mimicking the human sense of touch, namely, a device sensitive to contact forces, object slip and object geometry. This type of perception information is of paramount importance not only in dexterous manipulation but even in simple grasping tasks, especially when objects are fragile, such that only a minimum amount of grasping force can be applied to hold the object without damaging it. Moreover, sensing only forces and not moments can be very limiting to securely grasp an object when it is grasped far from its center of gravity. Therefore, the perception of torsional moments is a key requirement of the designed sensor. Furthermore, the sensor is also the mechanical interface between the gripper and the manipulated object, therefore its design should consider also the requirements for a correct holding of the object. The most relevant of such requirements is the necessity to hold a torsional moment, therefore a soft distributed contact is necessary. The presence of a soft contact poses a number of challenges in the calibration of the sensor, and that is another contribution of this work. Experimental validation is provided in real grasping tasks with two sensors mounted on an industrial gripper.

scholarly journals Dynamics of Multibody Systems With Spherical Clearance Joints

2005 ◽  
Author(s):  
P. Flores ◽  
J. Ambro´sio ◽  
J. C. P. Claro ◽  
H. M. Lankarani
Keyword(s):  
Contact Force ◽  
Multibody Systems ◽  
Contact Forces ◽  
Force Model ◽  
Clearance Joints ◽  
Continuous Contact ◽  
Clearance Joint ◽  
Contact Force Model ◽  
Dynamics Of Multibody Systems ◽  
The Impact

This work deals with a methodology to assess the influence of the spherical clearance joints in spatial multibody systems. The methodology is based on the Cartesian coordinates, being the dynamics of the joint elements modeled as impacting bodies and controlled by contact forces. The impacts and contacts are described by a continuous contact force model that accounts for geometric and mechanical characteristics of the contacting surfaces. The contact force is evaluated as function of the elastic pseudo-penetration between the impacting bodies, coupled with a nonlinear viscous-elastic factor representing the energy dissipation during the impact process. A spatial four bar mechanism is used as an illustrative example and some numerical results are presented, being the efficiency of the developed methodology discussed in the process of their presentation. The results obtained show that the inclusion of clearance joints in the modelization of spatial multibody systems significantly influences the prediction of components’ position and drastically increases the peaks in acceleration and reaction moments at the joints. Moreover, the system’s response clearly tends to be nonperiodic when a clearance joint is included in the simulation.

Direct Differential Kinematics of Hybrid-Chain Manipulators Including Singularity and Stability Analyses

1994 ◽  
Vol 116 (2) ◽  
pp. 614-621 ◽  
Author(s):  
Yong-Xian Xu ◽  
D. Kohli ◽  
Tzu-Chen Weng
Keyword(s):  
Stability Index ◽  
Inverse Kinematic ◽  
Degree Of Freedom ◽  
Static Force ◽  
Force Analysis ◽  
Kinematic Singularity ◽  
Numerical Examples ◽  
Transformation Matrices ◽  
Unstable Configuration ◽  
Direct Kinematics

A general formulation for the differential kinematics of hybrid-chain manipulators is developed based on transformation matrices. This formulation leads to velocity and acceleration analyses, as well as to the formation of Jacobians for singularity and unstable configuration analyses. A manipulator consisting of n nonsymmetrical subchains with an arbitrary arrangement of actuators in the subchain is called a hybrid-chain manipulator in this paper. The Jacobian of the manipulator (called here the system Jacobian) is a product of two matrices, namely the Jacobian of a leg and a matrix M containing the inverse of a matrix Dk, called the Jacobian of direct kinematics. The system Jacobian is singular when a leg Jacobian is singular; the resulting singularity is called the inverse kinematic singularity and it occurs at the boundary of inverse kinematic solutions. When the Dk matrix is singular, the M matrix and the system Jacobian do not exist. The singularity due to the singularity of the Dk matrix is the direct kinematic singularity and it provides positions where the manipulator as a whole loses at least one degree of freedom. Here the inputs to the manipulator become dependent on each other and are locked. While at these positions, the platform gains at least one degree of freedom, and becomes statically unstable. The system Jacobian may be used in the static force analysis. A stability index, defined in terms of the condition number of the Dk matrix, is proposed for evaluating the proximity of the configuration to the unstable configuration. Several illustrative numerical examples are presented.

Fixture Clamping Force Analysis during Milling Process

2013 ◽  
Vol 278-280 ◽  
pp. 385-388 ◽  
Author(s):  
Shao Gang Liu ◽  
Qiu Jin
Keyword(s):  
Analytical Method ◽  
Linear Equations ◽  
Milling Process ◽  
Contact Forces ◽  
Clamping Force ◽  
Contact Deformation ◽  
Force Analysis ◽  
Equilibrium Equations ◽  
Tangential Contact ◽  
Fixture Element

This paper presents a analytical method to calculate the minimum clamping force to prevent slippage between the workpiece and spherical-tipped fixture elements during milling process. After the contact deformation between the workpiece and spherical-tipped fixture element is determined, the relationships between the workpiece displacement and the contact deformations are obtained. Based on the static equilibrium equations, these equations are combined and linear equations are obtained to calculate the tangential contact forces between the workpiece and spherical-tipped fixture element. According to the maximum tangential contact force, the minimum clamping force to prevent slippage between the workpiece and spherical-tipped fixture elements is calculated. At last, this method is illustrated with a simulation example.

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