International Journal of Humanoid Robotics

In this paper, a walking engine that achieves dynamic stable walking using zero moment point (ZMP) criterion and feedback control from a gyro sensor is proposed. The ZMP criterion is used for the dynamic walking, and the feedback control from a gyro sensor is adopted for stabilization. The proposed walking engine consists of ZMP controller and the gait generator. The three-dimensional linear inverted pendulum model (3D-LIPM) is adopted for a simplified model of the humanoid robot. The ZMP equations are derived based on the 3D-LIPM and are applied to the gait generator. The walking engine is tested on a child-sized, 21-degree-of-freedom (DOF) humanoid robot cognitive humanoid autonomous robot with learning and evolutionary system (CHARLES) which stands 110cm tall and weighs only 8kg. The design concept of CHARLES is low development cost, lightweight, and simple design, which all match well with the proposed walking engine. The results of the experiments present the efficacy of the proposed walking engine.

In this paper, a robotic vehicle for a personal mobility with electric-driven three-wheels is proposed. Before designing the proposed robotics vehicle, omni-directional motions using special wheels, active caster wheels, and active steerable driving wheels are studied. For design of the proposed vehicle, we discuss about active steerable wheel design, and vehicle’s frame design. The omni-directional motion through the digital design exploration of the vehicle using active driving and steering wheel robot technology is examined. As the major mechanical components, an active steerable driving wheel, in-wheel motors, brakes, suspensions, and control systems are described. The design is established by rapid prototyping model of omni-directional motion. The steering geometry and control algorithm for the prototype of the proposed personal mobility are experimented.

In this paper, we developed a universal robot gripper using an electromagnet and a novel reforming magnetorheological (MR) fluid. First, we added nonmagnetic particles to an MR fluid to develop a novel reforming MR fluid called MR$\alpha$ fluid; this fluid resolved several issues faced with MR fluids. The developed fluid’s specific gravity is one-half and solidification hardness is two times that of MR fluid. The characteristics of the MR$\alpha$ fluid and an application that can control solidification under a magnetic field are described. Next, the developed gripper, which consists of an electromagnet and an elastic membrane that encloses the MR$\alpha$ fluid, is described. Further, several experimental results of the features and capabilities of the gripper are presented.

Intuitiveness in robotic surgery is highly desirable when performing highly elaborate surgical tasks using surgical master–slave systems (MSSs), such as suturing. To increase the operability of such systems, the time delay of the system response, haptic feedback, and eye–hand coordination are the issues that have received the most attention. In addition to these approaches, we propose a surgical robotic system that induces a multisensory illusion. In our previous study, we reported that a robotic instrument we devised enhances the multisensory illusion. In this paper, we determine the requirements for inducing this multisensory illusion in a multi-degree-of-freedom (DOF) MSS, and the first stage of prototype implementation based on the given requirements is described.

Rapid path following is an important component of a layered planning framework to improve motion speed. A method of generating a bipedal footstep sequence that follows a designated path and maintains stability in a planar environment is proposed in this paper. It adopts a walking style with a fixed step frequency and adjusts consecutive strides by eliminating irrational stride changes. An omnidirectional moving vehicle model and the deduced inequalities are introduced to theoretically describe the inter-pace constraints. A modified backtrack search is then implemented to solve the resulting constraint satisfaction problem. Both dynamics simulations and real robot experiments show that a humanoid robot is capable of tracking various paths with rapid paces. Comparison with several alternatives verifies the superiority of this novel method in terms of rapidity.

Wearable robotic systems have been a mechanism which clearly drives the motive of bringing back paraplegics back on their feet as well as executing difficult task beyond human ability. The purpose of this research study is to design and investigate the efficacy of rehabilitative walking in patients with lower limb disorders using oscillators which may commonly be referred to as central pattern generators (CPGs). In order to achieve this, a rhythmic trajectory is designed using Van der Pol oscillators. This rhythmic trajectory commensurates with the movement pattern of the hips and knees for a normal walking gait of humans. The dynamical model of a five-link biped exoskeletal device having four actuated joints is computed with regard to the wearer using Lagrangian principles in the sagittal plane. A feedback linearization control technique is therefore utilized for tracking the rhythmic trajectory to achieve a proper following of the human walking gait. Matlab/Simulink is used to validate this proposed strategy in the presence of uncertainties with a view to implementing it practically in the laboratory with human in the loop. Results show that humans with the aid of the exoskeleton device will possess the ability to track this rhythmic trajectory representing the hip and knee joint movements. The controller proved robust enough against disturbance.

This paper describes a design for a humanoid shoulder complex that replicates human shoulder girdle motion. The goal here is to use the minimum number of actuators to keep the mechanism as light as possible to help ensure that a humanoid is not too top heavy. The human shoulder girdle has two degrees-of-freedom (DOF), which means the minimum number of actuators is also two. The proposed mechanism is a novel parallel platform with two DOF that acts as a pointing mechanism. As the mechanism is articulated the end-effector moves, which results in contraction or elongation, mimicking the natural motion of the human shoulder girdle. A parallel platform was chosen because of the inherent rigidity and a large workspace is not necessary. The mechanism presented here was chosen because of its simplicity and ability to track human shoulder girdle motion. Motion studies were conducted to collect data representing human shoulder girdle motion, which was used to optimize the mechanism for tracking human shoulder girdle motion as closely as possible. A second optimization was performed to ensure that the mechanism avoids singularities throughout its entire range of motion. The results show that this design closely replicates human shoulder girdle motion and is well-suited for use as a humanoid shoulder girdle to increase the range of motion for a humanoid arm.

The aim of this paper is to reduce the energy consumption of a humanoid by analyzing electrical power as input to the robot and mechanical power as output. The analysis considers motor dynamics during standing up and sitting down tasks. The motion tasks of the humanoid are described in terms of joint position, joint velocity, joint acceleration, joint torque, center of mass (CoM) and center of pressure (CoP). To reduce the complexity of the robot analysis, the humanoid is modeled as a planar robot with four links and three joints. The humanoid robot learns to reduce the overall motion torque by applying Q-Learning in a simulated model. The resulting motions are evaluated on a physical NAO humanoid robot during standing up and sitting down tasks and then contrasted to a pre-programmed task in the NAO. The stand up and sit down motions are analyzed for individual joint current usage, power demand, torque, angular velocity, acceleration, CoM and CoP locations. The overall result is improved energy efficiency between 25–30% when compared to the pre-programmed NAO stand up and sit down motion task.

This paper proposes an analysis of the effect of vertical motion of the center of mass (COM) during humanoid walking. The linear inverted pendulum (LIP) model is classically used to deal with humanoid balance during walking. The effects on energy consumption of the COM height remaining constant for humanoid robots, or varying like human beings are studied here. Two approaches are introduced for the comparison: the LIP which offers the great advantage of analytical solving (i.e., fast and easy calculations), and a numerical solving of the IP dynamics, which allows varying the height of the center of mass during walking. The results are compared using a sthenic criterion in a 3D dynamics simulation of the humanoid robot Romeo (Aldebaran Robotics Company) and show a consequent reduction of the robot torque solicitation when the COM oscillates vertically.

Artificial torso is a fundamental part of humanoid robots with special features for mimicking human performance. In this paper, a novel torso design is presented with cable-driven vertebra-based solution, as inspired by human anatomy. Whereas the anatomy of the human torso and their joints are indeed very complex, a formulation for basic functioning of the humanoid torso has been developed. The structure is introduced by describing its main characteristics and performance starting from its kinematics up to design constrains. The design is presented with numerical results of dynamic simulation and FEM analysis with the aim of testing the feasibility of the proposed solution and characterizing its operation performance.