Posture Synthesis and Control of a Symmetric Hexapod Robot on Corrugated Surfaces for Underwater Observation

2007 ◽  
Author(s):  
Xin Wu ◽  
Yaoyu Li ◽  
Thomas R. Consi
Keyword(s):  
Degrees Of Freedom ◽  
Inverse Dynamics ◽  
Ccd Camera ◽  
The Body ◽  
Hexapod Robot ◽  
Corrugated Surfaces ◽  
Sensor Platform ◽  
Robotic Leg ◽  
And Control

This paper presents the first stage of a project to develop a six-legged walker (hexapod) as a highly stable mobile sensor platform for in situ benthic observation. The hexapod is radially symmetric with a downward looking, CCD camera-coupled, microscope mounted co-linear with the central axis of the body. A Lynxmotion (Peoria, IL) Model EH-3R radially symmetric 18 degrees-of-freedom hexapod robot has been used for initial land-based experiments and simplified to a 12 degree-of-freedom structure by locking the panning joint of each leg. Forward and inverse kinematics are then used to derive the relationship between the body posture and the proximal and distal joint angles on legs, which is the basis of the microscope’s coarse focusing for the observation. The kinematics analysis has been verified with both Matlab-based simulations and experiments on the hexapod prototype. Finally, passivity-based posture control is developed and simulated based on the inverse dynamics of the robotic leg.

Design and Fabrication of a Multi-Functional Nanomanipulator

2009 ◽  
Vol 419-420 ◽  
pp. 21-24
Author(s):  
Ming Chang ◽  
Chia Hung Lin ◽  
Chung Po Lin ◽  
Juti Rani Deka
Keyword(s):  
Degrees Of Freedom ◽  
Electrical Characterization ◽  
The Body ◽  
Rapid Expansion ◽  
Nano Materials ◽  
Nano Fabrication ◽  
Permissible Range ◽  
Manipulation System

With rapid expansion of nanotechnology, microminiaturization has become imperative in the field of micro/nano fabrication. A nanomanipulation system with high degrees of freedom that can perform nanomachining, nanofabrication and mechanical/electrical characterization of nanoscale objects inside a scanning electron microscope (SEM) is presented. The manipulation system consists of several individual operating units each having three linear stages and one rotational stage. The body of the manipulator is designed using the idea of superposition. Each operating unit can move in the permissible range of SEM’s vacuum chamber and can increase or decrease the number of units according to the requirement. Experiments were executed to investigate the in-situ electrical resistance of nano materials.

scholarly journals Fault-Tolerant Tripod Gait Planning and Verification of a Hexapod Robot

2020 ◽  
Vol 10 (8) ◽  
pp. 2959
Author(s):  
Yiqun Liu ◽  
Xuanxia Fan ◽  
Liang Ding ◽  
Jianfeng Wang ◽  
Tao Liu ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Fault Tolerant ◽  
Kinematic Model ◽  
Stability Margin ◽  
The Body ◽  
Hexapod Robot ◽  
Gait Planning ◽  
Phase Sequence ◽  
Gait Phase ◽  
Tripod Gait

In some hazardous or inaccessible applications, such as earthquake rescue, as a substitute for mankind, robots are expected to perform missions reliably. Unfortunately, the failure of components is difficult to avoid due to the complexity of robot composition and the interference of the environment. Thus, improving the reliability of robots is a crucial problem. The hexapod robot has redundant degrees of freedom due to its multiple joints, making it possible to tolerate the failure of one leg. In this paper, the Fault-Tolerant Tripod (F-TT) gait dealing with the failure of one leg is researched. The Denavit–Hartenberg (D-H) method is exploited to establish a kinematic model for the hexapod robot, the Jacobian matrix is analyzed, and it is proved that the body can be controlled when three legs are supported. Then, an F-TT gait phase sequence planning method based on a stability margin is established, and a method to improve stability is proposed. The trajectory for the center of gravity (COG) and foot is studied. Finally, a simulation model and prototype robot experiments are developed, and the effectiveness of the proposed method is verified.

scholarly journals Neuromuscular actuation of biohybrid motile bots

2019 ◽  
Vol 116 (40) ◽  
pp. 19841-19847 ◽  
Author(s):  
Onur Aydin ◽  
Xiaotian Zhang ◽  
Sittinon Nuethong ◽  
Gelson J. Pagan-Diaz ◽  
Rashid Bashir ◽  
...  
Keyword(s):  
Muscle Tissue ◽  
Motor Neurons ◽  
Neural Stimulation ◽  
The Body ◽  
Soft Robotics ◽  
Free Standing ◽  
Forward Locomotion ◽  
And Control ◽  
Drive Time

The integration of muscle cells with soft robotics in recent years has led to the development of biohybrid machines capable of untethered locomotion. A major frontier that currently remains unexplored is neuronal actuation and control of such muscle-powered biohybrid machines. As a step toward this goal, we present here a biohybrid swimmer driven by on-board neuromuscular units. The body of the swimmer consists of a free-standing soft scaffold, skeletal muscle tissue, and optogenetic stem cell-derived neural cluster containing motor neurons. Myoblasts embedded in extracellular matrix self-organize into a muscle tissue guided by the geometry of the scaffold, and the resulting muscle tissue is cocultured in situ with a neural cluster. Motor neurons then extend neurites selectively toward the muscle and innervate it, developing functional neuromuscular units. Based on this initial construct, we computationally designed, optimized, and implemented light-sensitive flagellar swimmers actuated by these neuromuscular units. Cyclic muscle contractions, induced by neural stimulation, drive time-irreversible flagellar dynamics, thereby providing thrust for untethered forward locomotion of the swimmer. Overall, this work demonstrates an example of a biohybrid robot implementing neuromuscular actuation and illustrates a path toward the forward design and control of neuron-enabled biohybrid machines.

scholarly journals Design and Control of 7-DOF Omni-directional Hexapod Robot

2020 ◽  
Vol 11 (1) ◽  
pp. 80-89
Author(s):  
Marek Žák ◽  
Jaroslav Rozman ◽  
František V. Zbořil
Keyword(s):  
Degrees Of Freedom ◽  
Travel Speed ◽  
Legged Robots ◽  
Movement Speed ◽  
Legged Robot ◽  
Hexapod Robot ◽  
Unique Combination ◽  
Two Degrees Of Freedom ◽  
And Control ◽  
Omnidirectional Wheels

AbstractLegged robots have great potential to travel across various types of terrain. Their many degrees of freedom enable them to navigate through difficult terrains, narrow spaces or various obstacles and they can move even after losing a leg. However, legged robots mostly move quite slowly. This paper deals with the design and construction of an omni-directional seven degrees of freedom hexapod (i.e., six-legged) robot, which is equipped with omnidirectional wheels (two degrees of freedom are used, one for turning the wheel and one for the wheel itself) usable on flat terrain to increase travel speed and an additional coxa joint that makes the robot more robust when climbing inclined terrains. This unique combination of omnidirectional wheels and additional coxa joint makes the robot not only much faster but also more robust in rough terrains and allows the robot to ride inclined terrains up to 40 degrees and remain statically stable in slopes up to 50 degrees. The robot is controlled by a terrain adaptive movement controller which adjusts the movement speed and the gait of the robot according to terrain conditions.

The Dynamics and Control of a Biped Walking Robot With Seven Degrees of Freedom

1996 ◽  
Vol 118 (4) ◽  
pp. 683-690 ◽  
Author(s):  
Ching-Long Shih
Keyword(s):  
Degrees Of Freedom ◽  
Biped Robot ◽  
The Body ◽  
Walking Robot ◽  
Walking Test ◽  
Biped Walking ◽  
Double Support ◽  
Dynamics And Control ◽  
Biped Walking Robot ◽  
And Control

This research studies the dynamics and motion control of a biped walking robot with seven degrees of freedom. The main features of the biped robot include variable length legs and a translatable balance weight in the body. The statically stable walking of the biped robot is implemented by maintaining the center-of-gravity (cg) inside the convex region of the supporting foot/feet during both single-support and double-support phases. The dynamically stable walking of the biped robot is realized by maintaining the zero moment point (ZMP), which is the virtual total ground reaction point, within the region of the supporting foot during the single-support phases. An implementation of a prototype biped BR-1 and its experimental walking test results are described. The biped robot is able to walk on an even floor both statically and dynamically. On a flat plane, the biped can walk with a speed of 8 cm/second statically, and 20 cm/second dynamically.

Design and control of a parallel mechanism haptic master for robot surgery using magneto-rheological clutches and brakes

2018 ◽  
Vol 29 (19) ◽  
pp. 3829-3844 ◽  
Author(s):  
Seung-Woo Cha ◽  
Seok-Rae Kang ◽  
Yong-Hoon Hwang ◽  
Seung-Bok Choi ◽  
Yang-Sup Lee ◽  
...  
Keyword(s):  
Tracking Control ◽  
Degrees Of Freedom ◽  
Repulsive Force ◽  
The Body ◽  
Tracking Accuracy ◽  
Magneto Rheological ◽  
Feed Forward Controller ◽  
Repulsive Forces ◽  
6 Degrees Of Freedom ◽  
And Control

This article presents tracking control performances of the repulsive force and torque of a haptic master with 6 degrees of freedom, which can be applied to robot-assisted minimally invasive surgeries. The proposed haptic master is activated by two types of actuators that use magneto-rheological fluid: magneto-rheological clutch and magneto-rheological brake. The body segment (or lower part) of the haptic master generates the repulsive forces for the three translational axes using the magneto-rheological clutch, while the wrist segment (or upper part) generates the repulsive torque for the three rotational axes through the use of the magneto-rheological brake. After analyzing the kinematic and dynamic equations, an appropriately sized haptic master is designed and manufactured. The field-dependent force and torque characteristics of the magneto-rheological actuators are experimentally investigated. Then, for successful tracking control performances, a fuzzy plus proportional–integral–derivative feedback controller is used for the repulsive force while a feed-forward controller associated with a hysteretic compensator for the repulsive torque. The effectiveness of the proposed 6-degree-of-freedom haptic master is experimentally validated by demonstrating high tracking accuracy of the force and torque.

scholarly journals Improving Inverse Dynamics Accuracy in a Planar Walking Model Based on Stable Reference Point

2014 ◽  
Vol 2014 ◽  
pp. 1-9
Author(s):  
Alaa Abdulrahman ◽  
Kamran Iqbal ◽  
Gannon White
Keyword(s):  
Human Body ◽  
Reference Point ◽  
Degrees Of Freedom ◽  
Inverse Dynamics ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
The Body ◽  
Sensor Position ◽  
Reaction Forces ◽  
The Cost

Physiologically and biomechanically, the human body represents a complicated system with an abundance of degrees of freedom (DOF). When developing mathematical representations of the body, a researcher has to decide on how many of those DOF to include in the model. Though accuracy can be enhanced at the cost of complexity by including more DOF, their necessity must be rigorously examined. In this study a planar seven-segment human body walking model with single DOF joints was developed. A reference point was added to the model to track the body’s global position while moving. Due to the kinematic instability of the pelvis, the top of the head was selected as the reference point, which also assimilates the vestibular sensor position. Inverse dynamics methods were used to formulate and solve the equations of motion based on Newton-Euler formulae. The torques and ground reaction forces generated by the planar model during a regular gait cycle were compared with similar results from a more complex three-dimensional OpenSim model with muscles, which resulted in correlation errors in the range of 0.9–0.98. The close comparison between the two torque outputs supports the use of planar models in gait studies.

Representing utility and deploying the body

2020 ◽  
Vol 43 ◽  
Author(s):  
David Spurrett
Keyword(s):  
Functional Activity ◽  
Degrees Of Freedom ◽  
The Body ◽  
Target Article ◽  
Processing Demands ◽  
The Many

Abstract Comprehensive accounts of resource-rational attempts to maximise utility shouldn't ignore the demands of constructing utility representations. This can be onerous when, as in humans, there are many rewarding modalities. Another thing best not ignored is the processing demands of making functional activity out of the many degrees of freedom of a body. The target article is almost silent on both.

A computer-control program for TEM in situ fatigue experiments

1989 ◽  
Vol 47 ◽  
pp. 620-621
Author(s):  
Kenneth S. Vecchio ◽  
John A. Hunt
Keyword(s):  
Slow Crack Growth ◽  
Computer Control ◽  
Control Program ◽  
Video Tape ◽  
Computer Control System ◽  
Transmission Electron ◽  
In Situ Experiments ◽  
Tremendous Amount ◽  
And Control

In-situ experiments conducted within a transmission electron microscope provide the operator a unique opportunity to directly observe microstructural phenomena, such as phase transformations and dislocation-precipitate interactions, “as they happen”. However, in-situ experiments usually require a tremendous amount of experimental preparation beforehand, as well as, during the actual experiment. In most cases the researcher must operate and control several pieces of equipment simultaneously. For example, in in-situ deformation experiments, the researcher may have to not only operate the TEM, but also control the straining holder and possibly some recording system such as a video tape machine. When it comes to in-situ fatigue deformation, the experiments became even more complicated with having to control numerous loading cycles while following the slow crack growth. In this paper we will describe a new method for conducting in-situ fatigue experiments using a camputer-controlled tensile straining holder.The tensile straining holder used with computer-control system was manufactured by Philips for the Philips 300 series microscopes. It was necessary to modify the specimen stage area of this holder to work in the Philips 400 series microscopes because the distance between the optic axis and holder airlock is different than in the Philips 300 series microscopes. However, the program and interfacing can easily be modified to work with any goniometer type straining holder which uses a penrmanent magnet motor.

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