International Journal of Humanoid Robotics

This paper introduces the design methodology, the modeling and the power consumption tests for a newly developed biped robot equipped with 12 DOFs. The robot is 1.1 meters tall (lower limbs) which makes it comparable in dimension with other state-of-the-art full-scale humanoids. By using a combination of 3D printing techniques and lightweight materials, the system weighs only 10.8kg (without batteries) while retaining high links strength and rigidity. Without compromising the workspace dimension, the robot presents a very low weight-to-height ratio (9.8kg/m) that translates into a safer operation and reduced energy consumption. To perform elementary locomotion primitives, e.g., changing the support from one foot to the other or lifting its body, the robot prototype consumes only 65 watts. Simulation results demonstrate the suitability of the robot’s kinematics to perform walking motion and predict an average power consumption of 200 watts. The direct kinematics of the robot is presented together with its inverse dynamics based on a Chaotic Recurrent Neural Network (CRNN). The adaptive model is identified using a recursive least squares algorithm that allows the CRNN to predict the torques at different step lengths with a MSE of 0.0057 on normalized data.

Robot dance is an important topic in robotics. Conventional robot dance systems mainly rely on beats or rhythms of music; however, these conventional systems suffer from limited dance styles and less action novelty. In this paper, we instead develop a humanoid robot dance system driven by musical structures and emotions. In the proposed system, a musical phrase and a dance phrase are considered as the basic structural units of music and dance, respectively. A musical phrasing algorithm based on music theories is created to divide a piece of music into a sequence of phrases. When the emotion of each phrase has been recognized, an emotion sequence can be established. Meanwhile, a hidden Markov model (HMM) matches a dance phrase sequence to the emotion sequence. In particular, several concepts of the “chance method” created by choreographer Merce Cunningham are adopted to guide our robot dance system; thus, a dance phrase is choreographed by randomly selecting and combining a number of actions from a predesigned action library. Based on the approach, one music can generate diverse robotic dance motions, showing the novelty and diversity of robot dance. The experiments on our humanoid robot “Alpha1 Pro” show that our robot can do a good job dancing to music according to musical structures and emotions and can be well accepted by various people.

The paper was published without confirmation from a ‘contributor’, and after mutual agreement they decided to retract the paper.

This paper presents the design process and construction of a mobile social robot companion “Arash” for educational and therapeutic intervention for children with chronic diseases; one which is based on their interests and needs. This study concentrates on children with cancer who suffer from physical pain caused by both the disease and its treatment. Moreover, cancer treatment causes emotional distress, which can reduce the efficiency of medications. Using social robots to interact with ill children in a hospital environment could decrease their distress, thereby improving the efficiency of the treatment. Arash is a 15 degrees-of-freedom cost effective humanoid mobile robot companion, designed and developed to interact with children ages 4 to 12 years old. The robot has five physical subsystems: head, arms, torso, waist, and the mobile-base. Based on the robot requirements and specifications, appropriate measures were generated and thoroughly evaluated. An important and novel concept is the robots appearance, selected based on a survey taken from 50 children with chronic diseases at three pediatric hospitals in the city of Tehran. Based on these criteria and needs, Arash was designed, constructed, modified, and developed to operate in pediatric hospital environments.

A key approach for reducing motor impairment and regaining independence after spinal cord injuries or strokes is frequent and repetitive functional training. A compatible exoskeleton (Co-Exoskeleton) with four passive translational joints is proposed for the upper-limb rehabilitation. There are only three passive translational joints to track and assist movements of the glenohumeral joint (GH), where two joints are installed horizontally at the front section and another one at the connecting interface of the upper arm. This type of configuration can lower the influences of gravities of the exoskeleton device and upper extremity. The kinematic models of GH and the corresponding human–machine system are established using the analytical method. A numerical simulation of the kinematic models is implemented with MATLAB to emphatically analyze the kinematic characteristics of passive joints and the center of Co-Exoskeleton. The translational displacements of passive joints in four elevation planes are obtained during the elevating process. The results of the kinematic analysis show that the passive joints have similar motion characteristics under different elevation planes. Additionally, the position changes of GH in three directions can be tracked and compensated approximately. Co-Exoskeleton has an especially good compensation effect for the vertical movement of GH. The compensation effect and kinematic models are verified by using the elevating experiments. This research provides theoretical and methodological guidance for the ergonomic design and kinematic analysis of the rehabilitation exoskeleton.

Tunable stiffness control is critical for undertaking surgical procedures using soft manipulators. However, active stiffness control in soft continuum manipulators is very challenging and has been rarely realized for real-time surgical applications. Low stiffness at the tip is much preferred for safe navigation of the robot in restricted spaces inside the human body. On the other hand, high stiffness at the tip is demanded for efficiently operating surgical instruments. In this paper, the manipulability and characteristics of a class of soft hyper-redundant manipulator, fabricated using Ecoflex-0050${}^{\text{TM}}$ silicone, is discussed and a new methodology is introduced to actively tune the stiffness matrix, in real-time, for disturbance rejection and stiffness control. Experimental results are used to derive a more accurate description of the characteristics of the soft manipulator, capture the varying stiffness effects of the actuated arm and consequently offer a more accurate response using closed loop feedback control in real-time. The novel results presented in this paper advances the state-of-the-art of tunable stiffness control in soft continuum manipulators for real-time applications.