Abstract:Parallel architectures are increasingly used as haptic devices to provide low inertia, high stiffness and compactness. Thus, spherical parallel manipulators have been developed to generate the three rotational movements in a sufficient workspace. However, these parallel structures have complex kinematic models and can suffer from critical singularity issues. This paper proposes a serial approach to solve the forward kinematic model of a spherical parallel manipulator, which is used as a haptic device in minima… Show more
“…The SPM is a 3-DOF orientation device and was examined in several works [3], [8], [13], [20], [38], [39], [40], [42], [43], [44], [45], [46], [51], [82] and was used in many applications [2], [18], [21], [27], [31], [36], [42], [46], [48], [49], [50], [55], [57], [58], [71], [72], [73], [74], [79], [83], [85]. Torque applied by the actuators in each of the three parallel linkages of the mechanism results in spherical rotation of the end-effector (EE) around the common centre point.…”
In this article, the solution to the inverse and forward kinematics of a novel three-legged, serialparallel, compliant robot are presented. The design of the robot aims to combine properties from serial and parallel architectures, thereby targeting an agile, yet precisely controllable robot that possibly allows both for dynamic locomotion and accurate manipulation tasks. The robot embodies the series connection of two parallel architectures, a planar and a spherical mechanism, realized in a highly dense mechanical assembly, allowing for lightweight, functionally redundant and compliant 4-DOF legs. A hybrid compliance behaviour is achieved, serving as a threshold between a stiff and compliant systemic state of the robot. Based on the mechanism design, the study involves the derivation of an alternative, yet complete solution for the inverse and forward kinematics of the spherical parallel manipulator (SPM). The approach utilizes spherical trigonometry and spatial vector geometry and yields a unique solution, while being both easy to implement and numerically efficient, thereby being applicable to real time implementations. Conceptually, a reduction of the mechanism assembly and working modes was directly integrated into the solution terms, drastically simplifying the expressions as they only represents the mechanically meaningful configuration relevant for actual physical systems. In addition to the active joint coordinates, the solution yields a unique set of all passively driven joints. The derived robot kinematics are furthermore verified through a 3D simulation model, showing the robot performing several motions. Thereby, the simulations portray the characteristics of the motor units by means of their corresponding phase profiles, revealing a balanced utilisation.INDEX TERMS Forward kinematics, inverse kinematics, legged robot, mechanical design, serial-parallel mechanism, spherical parallel manipulator.
“…The SPM is a 3-DOF orientation device and was examined in several works [3], [8], [13], [20], [38], [39], [40], [42], [43], [44], [45], [46], [51], [82] and was used in many applications [2], [18], [21], [27], [31], [36], [42], [46], [48], [49], [50], [55], [57], [58], [71], [72], [73], [74], [79], [83], [85]. Torque applied by the actuators in each of the three parallel linkages of the mechanism results in spherical rotation of the end-effector (EE) around the common centre point.…”
In this article, the solution to the inverse and forward kinematics of a novel three-legged, serialparallel, compliant robot are presented. The design of the robot aims to combine properties from serial and parallel architectures, thereby targeting an agile, yet precisely controllable robot that possibly allows both for dynamic locomotion and accurate manipulation tasks. The robot embodies the series connection of two parallel architectures, a planar and a spherical mechanism, realized in a highly dense mechanical assembly, allowing for lightweight, functionally redundant and compliant 4-DOF legs. A hybrid compliance behaviour is achieved, serving as a threshold between a stiff and compliant systemic state of the robot. Based on the mechanism design, the study involves the derivation of an alternative, yet complete solution for the inverse and forward kinematics of the spherical parallel manipulator (SPM). The approach utilizes spherical trigonometry and spatial vector geometry and yields a unique solution, while being both easy to implement and numerically efficient, thereby being applicable to real time implementations. Conceptually, a reduction of the mechanism assembly and working modes was directly integrated into the solution terms, drastically simplifying the expressions as they only represents the mechanically meaningful configuration relevant for actual physical systems. In addition to the active joint coordinates, the solution yields a unique set of all passively driven joints. The derived robot kinematics are furthermore verified through a 3D simulation model, showing the robot performing several motions. Thereby, the simulations portray the characteristics of the motor units by means of their corresponding phase profiles, revealing a balanced utilisation.INDEX TERMS Forward kinematics, inverse kinematics, legged robot, mechanical design, serial-parallel mechanism, spherical parallel manipulator.
“…Another solution is described in refs. [15, 16], which introduce a serial approach for solving the forward kinematic model by placing three sensors on one leg rather than placing them on the actuated joint located at the base. This solution aim to improve the calculation of the forward kinematic model and eliminate the parallel singularity effects in real time application. Figure 1. (a): SPM haptic device [23]; (b): haptic device based on Delta robot [17]; (c): hybrid haptic device for laparoscopic surgery [22].…”
This paper focuses on developing a novel hybrid-haptic (nHH) device with a remote center of rotation with 4 DOFs (degrees of freedom) intendant to be used as a haptic device. The new architecture is composed of two chains handling each one a part of the motions. It has the advantages of a parallel robot as high stiffness and accuracy, and the large workspace of the serial robots. The optimal synthesis of the nHH was performed using real-coded genetic algorithms. The optimization criteria and constraints were established and successively formulated and solved using a mono-objective function. A validation and comparison study were performed between the spherical parallel manipulator and the nHH. The obtained results are promising since the nHH is compared to other similar task devices, such as spherical parallel manipulator, and presents a suitable kinematic performance with a task workspace free singularity inside.
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