21,405 research outputs found
Novel Design and Analysis of Parallel Robotic Mechanisms
A parallel manipulator has several limbs that connect and actuate an end effector from the base. The design of parallel manipulators usually follows the process of prescribed task, design evaluation, and optimization. This dissertation focuses on interference-free designs of dynamically balanced manipulators and deployable manipulators of various degrees of freedom (DOFs).
1) Dynamic balancing is an approach to reduce shaking loads in motion by including balancing components. The shaking loads could cause noise and vibration. The balancing components may cause link interference and take more actuation energy. The 2-DOF (2-RR)R or 3-DOF (2-RR)R planar manipulator, and 3-DOF 3-RRS spatial manipulator are designed interference-free and with structural adaptive features. The structural adaptions and motion planning are discussed for energy minimization. A balanced 3-DOF (2-RR)R and a balanced 3-DOF 3-RRS could be combined for balanced 6-DOF motion.
2) Deployable feature in design allows a structure to be folded. The research in deployable parallel structures of non-configurable platform is rare. This feature is demanded, for example the outdoor solar tracking stand has non-configurable platform and may need to lie-flat on floor at stormy weathers to protect the structure. The 3-DOF 3-PRS and 3-DOF 3-RPS are re-designed to have deployable feature. The 6-DOF 3-[(2-RR)UU] and 5-DOF PRPU/2-[(2-RR)UU] are designed for deployable feature in higher DOFs. Several novel methods are developed for rapid workspace evaluation, link interference detection and stiffness evaluation.
The above robotic manipulators could be grouped as a robotic system that operates in a green way and works harmoniously with nature
Mechatronics integration for a vehicle simulator.
Master of Science in Mechanical Engineering. University of KwaZulu-Natal, Pietermaritzburg 2016.This dissertation presents the research and integration of a mechatronics system to be used in a vehicle simulator. The vehicle simulator is comprised of a 3-DOF platform which is used to provide motion cues to the driver. Kinematic analysis is performed on the 3-DOF system and this analysis assists in implementing platform motion control. To recreate the motion sensations experienced in an actual vehicle while respecting the platform workspace limits the classical washout algorithm is implemented in the vehicle simulator. A novel simulation system was contributed in Matlab/Simulink to aid in vehicle simulator design. This simulation setup incorporates all the motion cueing aspects; these aspects include input vehicle data scaling, the classical washout algorithm and inverse kinematic analysis. The developed simulation system was used to adjust the motion cueing parameters to ensure motion that respects the actuator motion constraints. These constraints ensure the vehicle simulator is operated safely.
A second contribution used the developed simulation system in Matlab/Simulink and the human vestibular system models. A performance evaluation was performed on the 3-DOF system against the traditional 6-DOF system. The results highlight the benefits of the 3-DOF system in replication of certain motion cues. Software was developed to receive input game data and output actuator stroke lengths to the motion control system. Limitations in the motion control system were found when testing was done on the vehicle simulator. These limitations led to a modified partial 2-DOF vehicle simulator. The motion control hardware is able to replicate actuator motion well. The final vehicle simulator system is a partial 2-DOF system that provides visual and motion cues that create a realistic driving experience. The developed system is suitable for applications with cost constraints and reasonable performance requirements
Design and motion control of a 6-UPS fully parallel robot for long bone fracture reduction : a thesis presented in partial fulfillment of the requirements for the degree of Master of Engineering in Mechatronics at Massey University
The incidences of long bone fractures in New Zealand are approximately 1 in 10,000. Long bones such as tibia and femur have complicated anatomic structures, making the realignment of these long bone fractures reliant on the skill of the surgeon. The drawbacks of current practice result in long time exposure to radiation, slow recovery and possible morbidity. A semi-automated long bone fracture reduction system based on a 6-DOF parallel robot platform has been in development since 2004. The developed 6-DOF parallel robot platform comprises of six linear actuators with rotary incremental encoders. To implement a realignment of long bone fractures, a framework for the 6-DOF platform robot has been developed. The inverse kinematics and singularity of the 6-DOF parallel robot has been studied to obtain the actions and Jacobin matrices. In motion control a multiple axis motion controller and amplifiers were used for 6-DOF parallel robot. PID tuning algorithms were developed based on the combination of the general tuning result and the contour control principle. The PID parameters have been validated by a number of experiments. The practical realignment of bone fractures requires a "Pull-Rotate-Push" action implemented by the 6-DOF parallel robot. After calibration, the reduction trajectories were generated accurately. The actual trials on the artificial fractures have shown that the robot developed is capable of performing the required reduction motion
Kinematics, workspace and singularity analysis of a multi-mode parallel robot
A family of reconfigurable parallel robots can change motion modes by passing
through constraint singularities by locking and releasing some passive joints
of the robot. This paper is about the kinematics, the workspace and singularity
analysis of a 3-PRPiR parallel robot involving lockable Pi and R (revolute)
joints. Here a Pi joint may act as a 1-DOF planar parallelogram if its
lock-able P (prismatic) joint is locked or a 2-DOF RR serial chain if its
lockable P joint is released. The operation modes of the robot include a 3T
operation modes to three 2T1R operation modes with two different directions of
the rotation axis of the moving platform. The inverse kinematics and forward
kinematics of the robot in each operation modes are dealt with in detail. The
workspace analysis of the robot allow us to know the regions of the workspace
that the robot can reach in each operation mode. A prototype built at
Heriot-Watt University is used to illustrate the results of this work.Comment: International Design Engineering Technical Conferences \& Computers
and Information in Engineering Conference, Aug 2017, Cleveland, United
States. 201
Design, analysis, and control of a cable-driven parallel platform with a pneumatic muscle active support
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.The neck is an important part of the body that connects the head to the torso, supporting the weight and generating the movement of the head. In this paper, a cable-driven parallel platform with a pneumatic muscle active support (CPPPMS) is presented for imitating human necks, where cable actuators imitate neck muscles and a pneumatic muscle actuator imitates spinal muscles, respectively. Analyzing the stiffness of the mechanism is carried out based on screw theory, and this mechanism is optimized according to the stiffness characteristics. While taking the dynamics of the pneumatic muscle active support into consideration as well as the cable dynamics and the dynamics of the Up-platform, a dynamic modeling approach to the CPPPMS is established. In order to overcome the flexibility and uncertainties amid the dynamic model, a sliding mode controller is investigated for trajectory tracking, and the stability of the control system is verified by a Lyapunov function. Moreover, a PD controller is proposed for a comparative study. The results of the simulation indicate that the sliding mode controller is more effective than the PD controller for the CPPPMS, and the CPPPMS provides feasible performances for operations under the sliding mode control
An Open-Source 7-Axis, Robotic Platform to Enable Dexterous Procedures within CT Scanners
This paper describes the design, manufacture, and performance of a highly
dexterous, low-profile, 7 Degree-of-Freedom (DOF) robotic arm for CT-guided
percutaneous needle biopsy. Direct CT guidance allows physicians to localize
tumours quickly; however, needle insertion is still performed by hand. This
system is mounted to a fully active gantry superior to the patient's head and
teleoperated by a radiologist. Unlike other similar robots, this robot's fully
serial-link approach uses a unique combination of belt and cable drives for
high-transparency and minimal-backlash, allowing for an expansive working area
and numerous approach angles to targets all while maintaining a small in-bore
cross-section of less than . Simulations verified the system's
expansive collision free work-space and ability to hit targets across the
entire chest, as required for lung cancer biopsy. Targeting error is on average
on a teleoperated accuracy task, illustrating the system's sufficient
accuracy to perform biopsy procedures. The system is designed for lung biopsies
due to the large working volume that is required for reaching peripheral lung
lesions, though, with its large working volume and small in-bore
cross-sectional area, the robotic system is effectively a general-purpose
CT-compatible manipulation device for percutaneous procedures. Finally, with
the considerable development time undertaken in designing a precise and
flexible-use system and with the desire to reduce the burden of other
researchers in developing algorithms for image-guided surgery, this system
provides open-access, and to the best of our knowledge, is the first
open-hardware image-guided biopsy robot of its kind.Comment: 8 pages, 9 figures, final submission to IROS 201
Kinematically Redundant Octahedral Motion Platform for Virtual Reality Simulations
We propose a novel design of a parallel manipulator of Stewart Gough type for
virtual reality application of single individuals; i.e. an omni-directional
treadmill is mounted on the motion platform in order to improve VR immersion by
giving feedback to the human body. For this purpose we modify the well-known
octahedral manipulator in a way that it has one degree of kinematical
redundancy; namely an equiform reconfigurability of the base. The instantaneous
kinematics and singularities of this mechanism are studied, where especially
"unavoidable singularities" are characterized. These are poses of the motion
platform, which can only be realized by singular configurations of the
mechanism despite its kinematic redundancy.Comment: 13 pages, 6 figure
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