Design and Performance Analysis of LARMbot Torso V1

In this paper, laboratory experiments of LARMbot torso V1 are reported in the third mode, thereby providing a testing characterization. Sensors were used to measure parameters including the contact force between the shoulder and cables, linear acceleration, angles of the torso body, and power consumption. The results showed that the LARMbot torso V1 can bend successfully to the desired angles, and that it is able to complete a full motion smoothly. The LARMbot torso V1 can mimic human-like motiaons. Based on our analysis of the test results, improvements are suggested, and new designs are considered.

Kinematic Modelling and Motion Analysis of a Humanoid Torso Mechanism

This paper introduces a novel kinematic model for a tendon-driven compliant torso mechanism for humanoid robots, which describes the complex behaviour of a system characterised by the interaction of a complex compliant element with rigid bodies and actuation tendons. Inspired by a human spine, the proposed mechanism is based on a flexible backbone whose shape is controlled by two pairs of antagonistic tendons. First, the structure is analysed to identify the main modes of motion. Then, a constant curvature kinematic model is extended to describe the behaviour of the torso mechanism under examination, which includes axial elongation/compression and torsion in addition to the main bending motion. A linearised stiffness model is also formulated to estimate the static response of the backbone. The novel model is used to evaluate the workspace of an example mechanical design, and then it is mapped onto a controller to validate the results with an experimental test on a prototype. By replacing a previous approximated model calibrated on experimental data, this kinematic model improves the accuracy and efficiency of the torso mechanism and enables the performance evaluation of the robot over the reachable workspace, to ensure that the tendon-driven architecture operates within its wrench-closure workspace.

Parallel Architectures for Humanoid Robots

The structure of humanoid robots can be inspired to human anatomy and operation with open challenges in mechanical performance that can be achieved by using parallel kinematic mechanisms. Parallel mechanisms can be identified in human anatomy with operations that can be used for designing parallel mechanisms in the structure of humanoid robots. Design issues are outlined as requirements and performance for parallel mechanisms in humanoid structures. The example of LARMbot humanoid design is presented as from direct authors’ experience to show an example of the feasibility and efficiency of using parallel mechanisms in humanoid structures. This work is an extension of a paper presented at ISRM 2019 conference (International Symposium on Robotics and Mechatronics).

Design and wrench-feasible workspace analysis of a cable-driven hybrid joint

This article proposes a cable-driven hybrid joint (CDHJ), focuses on the effects of external wrench payload and structural parameters on the wrench-feasible workspace for the preliminary design of the mechanism, and further discusses the wrench exertion capability of the mechanism under a certain configuration. This CDHJ has central rigid support with a revolute pair and a central compression spring support. Due to the unilateral property of cables and the flexible compression spring, the kinematic model cannot define the workspace directly; it should be combined with the statics for possible solution, including the spring lateral buckling model based on the elliptic integral solution. Moreover, a global tension index which is to evaluate the wrench-closure property of the global workspace, combined with an index which is to assess the size of the workspace, is proposed to better compare the effects of different external wrench payloads and different structural parameters on the workspace. Simulations were performed and demonstrated the correctness and feasibility of the inverse kinematics and workspace analysis of the joint. Hence, the proposed mechanism has potential use in robotics especially in wheelchair-mounted robotic manipulator joint.

Sensorless External Force Detection Method for Robot Arm Based on Error Compensation Using BP Neural Network

This paper proposes an external force detection method for humanoid robot arm without using joint torque sensors, which can detect the external force of the joint space in real time during the operation of the robot. We first analyzed the structure of the humanoid robot arm we designed, and then established the external force detection model of the robot arm based on robot dynamics and motor dynamics. Subsequently, analyses were conducted on the error of the detection model and the dynamic model error of the robot arm is compensated by using the artificial neural network method to obtain more accurate external force value for the robot arm. In experiment, the accuracy test and the collision test were performed on the detected extern forces of the robot arm. The results show that the method can effectively improve the detection accuracy of the robot arm, and the robot arm can realize the real-time collision detection during its static and running states, which can ensure the safe operation of the robot.

Mechanism Design of a Humanoid Robotic Torso Based on Bionic Optimization

A new torso structure for a humanoid robot has been proposed. The structural characteristics and functions of human torso have been considered to gain inspirations for design purposes. The proposed torso structure consists of six revolute units divided into two basic categories connected in a serial chain mechanism. The proposed torso structure shows more advantages compared to traditional humanoid robots in terms of high degrees of freedom (DOFs), high stiffness, self-locking capabilities, as well as easy-to-control features. Bionic optimization design based on objective function method has been implemented on structural design for better motion performances. A 3D model has been elaborated and simulated in SolidWorks and ADAMS environments for structural design and kinematic simulation purposes, respectively. Simulation results show that the new bionic torso structure is able to well imitate movements of human torso.

Characteristics and Performance of CAUTO (CAssino hUmanoid TOrso) Prototype

An artificial torso is a fundamental part of a humanoid robot for imitating human actions. In this paper, a prototype of CAUTO (CAssino hUmanoid TOrso) is presented. Its design is characterized by artificial vertebras actuated by cable-driven parallel manipulators. The design was conceived by looking at the complex system and functioning of the human torso, in order to develop a solution for basic human-like behavior. The requirements and kinematic structure are introduced to explain the peculiarities of the proposed mechanical design. A prototype is presented, and built with low-cost and high-performance features. Tests results are reported to show the feasibility and the characteristics in replicating human torso motions. In addition, the power consumption has been measured during the tests to prove the efficiency of the Li-Po battery supply, employed for a fully portable solution of the designed torso.