From Differential Geometry of Curves to Helical Kinematics of Continuum Robots Using Exponential Mapping

Kinematic modeling of continuum robots is challenging due to the large deflections that these systems usually undergone. In this paper, we derive the kinematics of a continuum robot from the evolution of a three-dimensional curve in space. We obtain the spatial configuration of a continuum robot in terms of exponential coordinates based on Lie group theory. This kinematic framework turns out to handle robotic helical shapes, i.e. spatial configurations with constant curvature and torsion of the arm

Modeling of Inverse Kinematic Analysis of Open-Source Medical Assist Robot Arm by Python

Today, the epidemic diseases such as COVID-19 spreads very fast in the globalizing world and lethal effects on human health have had a noticeable effect on the health sector. For this situations, various disciplines have had different studies to minimize the effects of the epidemic. In such cases, it is a separate requirement that the use of the opportunities brought by technology. In this study, the kinematic analysis of the open-source robot arm was especially examined in terms of reducing the workload of individuals working in the healthcare sector. The open-source robot arm is articulated and has 5 degrees of freedom. The kinematic analysis is very important for determination of the working space of the robotic systems. The inverse kinematic analysis was done with Python programming language and the control module was developed to check the analysis. The control module shows the angle values depending on the joints of the robot arm. It is also shown the Px, Py, and Pz positions obtained depending on the position of the end effector in 3D space. On the other hand, Euler angle values are also specified, which are based on the position of the last position taken by the joints of the robot arm in the 3D space. In the study, the geometric approach method was used that is still popular in the inverse kinematic analysis. It is hoped that this study will inspire the development and use of professional and industrial kinds of the open-source robot arm

A circular pneumatic muscle actuator (CPMA) inspired by human skeletal muscles

This paper illustrates the design, implementation and kinematics of a novel circular pneumatic muscle actuator (CPMA), inspired by the skeletal muscles of a human. The variation of the inner diameter of this actuator is a unique feature. Furthermore, CPMA produces a radial force towards its centre by increasing the diameter of the actuator itself in addition to the reduction in the inner diameter. These performances make the presented actuator suitable to use in numerous applications. The grasping by a soft gripper is chosen as an application to design an efficient soft gripper by using single and multiple CPMAs

Novel models for the extension pneumatic muscle actuator performances

This paper illustrates the design, implementation and modelling of the extensor pneumatic muscle actuator (PMA). The extensor soft actuator has a vital feature of ability to bend and extend, and that give it the flexibility to use in numerous applications. The extended behaviour of this actuator is modelled mathematically to be used to predict the length of a wide range of actuators at different air pressure amounts and make the position control of such type of actuator easier and precise. Moreover, the contraction force formula is modified to describe the pushing force for the extensor actuator. The bending behaviour of single muscle is explained and a 4-PMA continuum arm has been constructed to study its performance and model the bending angle

A FEM-experimental approach for the development of a conceptual linear actuator based on tendril's free coiling

Within the vastness of the plant species, certain living systems show tendril structures whose motion is of particular interest for biomimetic engineers. Tendrils sense and coil around suitable grips, and by shortening in length, they erect the remaining plant body. To achieve contraction, tendrils rotate along their main axis and shift from a linear to a double-spring geometry. This phenomenon is denoted as the free-coiling phase. In this work, with the aim of understanding the fundamentals of the mechanics behind the free coiling, a reverse-engineering approach based on the finite element method was firstly applied. The model consisted of an elongated cylinder with suitable material properties, boundary, and loading conditions, in order to reproduce the kinematics of the tendril. The simulation succeeded in mimicking coiling faithfully and was therefore used to validate a tentative linear actuator model based on the plant’s working principle. More in detail, exploiting shape memory alloy materials to obtain large reversible deformations, the main tendril features were implemented into a nickel-titanium spring-based testing model. The results of the experimental tests confirmed the feasibility of the idea in terms of both functioning principles and actual performance. It can be concluded that the final set-up can be used as a base for a prototype design of a new kind of a linear actuator

Discrete Cosserat Approach for Multi-Section Soft Robots Dynamics

In spite of recent progress, soft robotics still suffers from a lack of unified modeling framework. Nowadays, the most adopted model for the design and control of soft robots is the piece-wise constant curvature model, with its consolidated benefits and drawbacks. In this work, an alternative model for multisection soft robots dynamics is presented based on a discrete Cosserat approach, which, not only takes into account shear and torsional deformations, essentials to cope with out-of-plane external loads, but also inherits the geometrical and mechanical properties of the continuous Cosserat model, making it the natural soft robotics counterpart of the traditional rigid robotics dynamics model. The soundness of the model is demonstrated through extensive simulation and experimental results for both plane and out-of-plane motions.Comment: 13 pages, 9 figure