Dynamic Active Constraints for Surgical Robots using Vector Field Inequalities

Robotic assistance allows surgeons to perform dexterous and tremor-free procedures, but robotic aid is still underrepresented in procedures with constrained workspaces, such as deep brain neurosurgery and endonasal surgery. In these procedures, surgeons have restricted vision to areas near the surgical tooltips, which increases the risk of unexpected collisions between the shafts of the instruments and their surroundings. In this work, our vector-field-inequalities method is extended to provide dynamic active-constraints to any number of robots and moving objects sharing the same workspace. The method is evaluated with experiments and simulations in which robot tools have to avoid collisions autonomously and in real-time, in a constrained endonasal surgical environment. Simulations show that with our method the combined trajectory error of two robotic systems is optimal. Experiments using a real robotic system show that the method can autonomously prevent collisions between the moving robots themselves and between the robots and the environment. Moreover, the framework is also successfully verified under teleoperation with tool-tissue interactions.Comment: Accepted on T-RO 2019, 19 Page

Dynamics of Serial Manipulators using Dual Quaternion Algebra

This paper presents two approaches to obtain the dynamical equations of serial manipulators using dual quaternion algebra. The first one is based on the recursive Newton-Euler formulation and uses twists and wrenches instead of 3D vectors, which simplifies the classic procedure by removing the necessity of exhaustive geometrical analyses since wrenches and twists are propagated through high-level algebraic operations. Furthermore, the proposed formulation works for arbitrary types of joints and does not impose any particular convention for the propagation of twists. The second approach, based on Gauss's Principle of Least Constraint (GPLC), takes into account elements of the dual quaternion algebra and provides a linear relationship between twists derivatives and joint accelerations, which can be particularly useful in robot control. Differently from other approaches based on the GPLC, which have representational singularities or require constraints, our method does not have those drawbacks. We present a thorough methodology to obtain the computational cost of both algorithms and compared them with their classic counterparts. Although our current formulations are more computationally expensive, they are more general than their counterparts in the state of the art. Simulation results showed that both methods are as accurate as the classic recursive Newton-Euler algorithm.Comment: Submitted for publication (currently under review

Advanced quaternion forward kinematics algorithm including overview of different methods for robot kinematics

Formulisanje odgovarajućih i efikasnih algoritama kinematike robota je od suštinskog značaja za analizu i razvoj serijskih manipulatora. Kinematičko modelovanje manipulatora se najčešće vrši u Dekartovom prostoru. Međutim, usled nedostataka najzastupljenijih matematičkih operatora za definisanje orijentacije kao što su Ojlerovi uglovi i rotacione matrice, nameće se potreba za jednoznačnim, kompaktnim, računski efikasnim metodom za određivanje orijentacije. Kao rešenje ovog problema predlažu se jedinični kvaternioni kao i razvoj kinematičkih modela u prostoru dualnih kvaterniona. U ovom radu je dat pregled geometrijskih opisa i transformacija koje se mogu primeniti u okviru navedenih prostora kako bi se rešili problemi kinematike robota. Poseban akcenat je na različitim matematičkim formalizmima koji se koriste za definisanje orijentacije krutog tela, kao što su rotacione matrice, Ojlerovi uglovi, osa i ugao rotacije, jedinični kvaternioni, kao i na njihovoj uzajamnoj vezi. Prednosti kinematičkog modeliranja u prostoru kvaterniona su istaknute. Osobine jediničnih i dualnih kvaterniona se analiziraju sa stanovišta robotike. Takođe, dat je novi algoritam direktne kinematike robota u prostoru dualnih kvaterniona. Ovaj algoritam je primenjen na humanoj centrifugi koja je modelirana kao troosni manipulator.Formulation of proper and efficient algorithms for robot kinematics is essential for the analysis and design of serial manipulators. Kinematic modeling of manipulators is most often performed in Cartesian space. However, due to disadvantages of most widely used mathematical constructs for description of orientation such as Euler angles and rotational matrices, a need for unambiguous, compact, singularity free, computationally efficient method for representing rotational information is imposed. As a solution, unit quaternions are proposed and kinematic modeling in dual quaternion space arose. In this paper, an overview of spatial descriptions and transformations that can be applied together within these spaces in order to solve kinematic problems is presented. Special emphasis is on a different mathematical formalisms used to represent attitude of a rigid body such as rotation matrix, Euler angles, axis-angle representation, unit quaternions, and their mutual relation. Benefits of kinematic modeling in quaternion space are presented. New direct kinematics algorithm in dual quaternion space pertaining to a particular manipulator is given. These constructs and algorithms are demonstrated on the human centrifuge as 3 DoF robot manipulator

Advanced quaternion forward kinematics algorithm including overview of different methods for robot kinematics

Formulisanje odgovarajućih i efikasnih algoritama kinematike robota je od suštinskog značaja za analizu i razvoj serijskih manipulatora. Kinematičko modelovanje manipulatora se najčešće vrši u Dekartovom prostoru. Međutim, usled nedostataka najzastupljenijih matematičkih operatora za definisanje orijentacije kao što su Ojlerovi uglovi i rotacione matrice, nameće se potreba za jednoznačnim, kompaktnim, računski efikasnim metodom za određivanje orijentacije. Kao rešenje ovog problema predlažu se jedinični kvaternioni kao i razvoj kinematičkih modela u prostoru dualnih kvaterniona. U ovom radu je dat pregled geometrijskih opisa i transformacija koje se mogu primeniti u okviru navedenih prostora kako bi se rešili problemi kinematike robota. Poseban akcenat je na različitim matematičkim formalizmima koji se koriste za definisanje orijentacije krutog tela, kao što su rotacione matrice, Ojlerovi uglovi, osa i ugao rotacije, jedinični kvaternioni, kao i na njihovoj uzajamnoj vezi. Prednosti kinematičkog modeliranja u prostoru kvaterniona su istaknute. Osobine jediničnih i dualnih kvaterniona se analiziraju sa stanovišta robotike. Takođe, dat je novi algoritam direktne kinematike robota u prostoru dualnih kvaterniona. Ovaj algoritam je primenjen na humanoj centrifugi koja je modelirana kao troosni manipulator.Formulation of proper and efficient algorithms for robot kinematics is essential for the analysis and design of serial manipulators. Kinematic modeling of manipulators is most often performed in Cartesian space. However, due to disadvantages of most widely used mathematical constructs for description of orientation such as Euler angles and rotational matrices, a need for unambiguous, compact, singularity free, computationally efficient method for representing rotational information is imposed. As a solution, unit quaternions are proposed and kinematic modeling in dual quaternion space arose. In this paper, an overview of spatial descriptions and transformations that can be applied together within these spaces in order to solve kinematic problems is presented. Special emphasis is on a different mathematical formalisms used to represent attitude of a rigid body such as rotation matrix, Euler angles, axis-angle representation, unit quaternions, and their mutual relation. Benefits of kinematic modeling in quaternion space are presented. New direct kinematics algorithm in dual quaternion space pertaining to a particular manipulator is given. These constructs and algorithms are demonstrated on the human centrifuge as 3 DoF robot manipulator

A Comparative Study of Three Inverse Kinematic Methods of Serial Industrial Robot Manipulators in the Screw Theory Framework

In this paper, we compare three inverse kinematic formulation methods for the serial industrial robot manipulators. All formulation methods are based on screw theory. Screw theory is an effective way to establish a global description of rigid body and avoids singularities due to the use of the local coordinates. In these three formulation methods, the first one is based on quaternion algebra, the second one is based on dual-quaternions, and the last one that is called exponential mapping method is based on matrix algebra. Compared with the matrix algebra, quaternion algebra based solutions are more computationally efficient and they need less storage area. The method which is based on dual-quaternion gives the most compact and computationally efficient solution. Paden-Kahan sub-problems are used to derive inverse kinematic solutions. 6-DOF industrial robot manipulator\u27s forward and inverse kinematic equations are derived using these formulation methods. Simulation and experimental results are given

The geometric structure of unit dual quaternion with application in kinematic control

AbstractIn this paper, the geometric structure, especially the Lie-group related properties, of unit dual quaternion is investigated. The exponential form of unit dual quaternion and its approximate logarithmic mapping are derived. Correspondingly, Lie-group and Lie-algebra on unit dual quaternions and the approximate logarithms are explored, respectively. Afterwards, error and metric based on unit dual quaternion are given, which naturally result in a new kinematic control model with unit dual quaternion descriptors. Finally, as a case study, a generalized proportional control law using unit dual quaternion is developed

Dual quaternion-based inverse kinematics of dexterous finger

The inverse kinematics solution of a dexterous robotic finger has a significant impact on the real-time control of the robotic hand. Therefore a rapid method for solving is needed. The classical homogeneous matrix transformation is the most popular method used in robot kinematics. However, for the multi degree-of-freedom (DOF) robotic finger, the matrix parameters cost much storage and the inverse matrix calculation requires a large amount of computational cost. So it is not conducive to the real-time control of the robotic hand. Therefore, a method based on dual quaternions is presented for analysing the kinematics of a multi-DOF (4-DOF) robotic thumb. Firstly, the kinematics equation is expressed by dual quaternions. Then the multivariate kinematic equations are converted to binary quadratic equations with methods of separating variables and variable substitution, which is relatively easy to obtain the closed-form solution of the inverse kinematics. Finally, it proves that the dual quaternions method has advantages over the homogeneous matrix transformation in storage and computational cost by the specific numbers for the robotic thumb, which is conducive to the real-time control of robotic hand