Applied Mechanics and Materials Vol. 461

Abstract: Considering the sagittal movement and the lateral swing in the humanoid practical walking, a new humanoid passive dynamic bipedal robot with the lateral movable upper body is proposed in this paper. The finite state machine (FSM) theory is adopted to control the robot, which changes agilely the control strategy according to the practical states of the humanoid gait. In the method, the torque compensation adaptive excitation control strategy is used for sagittal control and PID is applied to the upper body for the robots lateral stability. It is verified by the co-simulation based on ADAMS and MATLAB that the bipedal robot can reach the stable humanoid gait with the high energy efficiency.

Abstract: Because the direction goals of the snake robot are different in applications, e.g. the target point and target path, the direction control of a snake robot is a challenging problem. We have proposed a control method, which is called passive creeping based on the energy balance. In this paper, the direction of the snake robot which is controlled by the passive creeping control method is discussed. A new direction control method which is based on the torque compensation is proposed. The direction control method set a universal direction goal for all the applications. The torque of the head joint which leads the locomotion direction is adjusted by the torque compensation. The compensated torque decreases the angle between the direction of the body axis and the expected direction by the exponential decay function. In simulation, the trajectory and the angle express the process of direction adjustment. The error analysis proves the validity and adaptability of the proposed direction control. Also the validity of the proposed method is proved by the experiment which is based on the virtual/physical mixed experimental system.

Abstract: Abstract. Octopus can achieve a variety of dexterous movements at any point along its arm, such as elongating, shorting, bending, twisting, or changing the stiffness, which have been considered as an interesting model of inspiration in robotics. Among the complex behaviors, the torsion behavior is important because it provide extra degree of freedom of movement, like twisting. This paper proposed a detailed dynamic model that describes the torsion behavior of octopus arm, based on torsional vibration theory. The initial conditions and boundary conditions that explained the main features of the torsion behaviors of octopus arm are acknowledged. The mode shapes, which describe the torsional vibration frequency and type, were solved as the sum of the time and the distance from the fixed end to where the deformation happened. By comparing the mode shapes results solved by the method proposed in this paper and by FEA Soft ANSYS, the effectiveness of this method has been verified. Further torsional stresses and torsion angles of deformation and vibrations on rod can be expressed as the functions of the mode shapes and the external torque exerted on one end of the rod. This method can be applied to calculate the kinematics results of the torsion behaviors and the appropriate activations related for continuum robotic manipulators inspired by octopus arm.

Abstract: Abstract: Purpose：By investigating the variation of the human walking gait kinematics with respect to the foot deformation constraint, prove that bionic design of feet are the necessity for biped robots to imitate human walking better in terms of flexibility, stability and efficiency. The results will be significant for future research and development of biped robots. Methods: A human being was assumed as a perfect biped robot which had ideal motion drive and control. The walking gait parameters of two healthy men with foot deformation unconstrained and constrained were tested respectively by the inertia motion capture suit, and then they were processed by programming and analyzed by comparison. Results: The data analysis showed that when subjects walked with foot deformation constrained, their angular displacements of lower limb joints generally increased, the curves of angular velocity and accelerations fluctuated in certain walking phases, the walking pace and stride length decreased obviously, the single support phase shortened while the double support phase lengthened. At the same time, subjects felt subjectively that their body motion was less flexible, the walking posture was difficult to control, and the walking stability was more strenuous to keep. Conclusion: Combining the logical analogies with the detailed experimentation results, it is inferred that biped robots with rigid feet will have to suffer awkward and unstable walking gait, heavier and strenuous steps, and lower energy efficiency while walking. The paper concludes the necessity of bionic design of the robot feet for improving the walking quality of the biped robots. The conclusion and the experiment data will be of significant value for future work of robot design and evaluation.

Abstract: In this paper, helix tails with rectangular cross-section were designed for propelling a kind of flagella-like swimming robot. CFD (Computational Fluid Dynamics) software was applied to analyze the major influencing factors of the robots mechanical properties. It is revealed that the thrust reaches the maximum when the helix tails cross-section width is 0.36 times the diameter. Meanwhile, the helix tails should be designed according to the requirements with the largest diameter, close to but less than 45° helix angle and multi-turns under the limitation of the workspace. Combining these simulation data with the derivation process of Resistive Force Theory, the models for the mechanical properties simulation of the swimming robot were revised, and the explicit empirical formula of propulsive force is obtained. This model lays a good foundation for the robots motion control as well as unified mathematical description for macro-scale and micro-scale robots.

Abstract: People have learnt from biological system behaviours and structures to design and develop a number of different kinds of optimisation algorithms that have been widely used in both theoretical study and practical applications in engineering and business management. An efficient supply chain is very important for companies to survive in global competitive market. An effective SCM (supply chain management) is the key for implement an efficient supply chain. Though there have been considerable amount of study of SCM, there have been very limited publications of applying the findings from the biological system study into SCM. In this paper, through systematic literature review, various SCM issues and requirements are discussed and some typical biological system behaviours and natural-inspired algorithms are evaluated for the purpose of SCM. Then the principle and possibility are presented on how to learn the biological systems' behaviours and natural-inspired algorithms for SCM and a framework is proposed as a guide line for users to apply the knowledge learnt from the biological systems for SCM. In the framework, a number of the procedures have been presented for using XML to represent both SCM requirement and bio-inspiration data. To demonstrate the proposed framework, a case study has been presented for users to find the bio-inspirations for some particular SCM problems in automotive industry.

Abstract: This article aims to propose an optimized active yaw moment distribution strategy to improve vehicle safety and stability effectively. A controller based on a 2 DOF vehicle model and a PID controller is designed for the target active yaw moment, which is further allocated into longitudinal tire forces optimally by a particle swarm optimization (PSO) algorithm. The optimal distribution strategy is analyzed using Carsim and Matlab/Simulink co-simulation. The results show that the vehicle handling and stability are improved effectively through the lower workload of the actuators by the proposed control strategy.

Abstract: This paper presents a preliminary idea for sensing the deformation of ion-conductive polymer metal composite (IPMC) actuator based on current detection. This method is based on the principle that the impedance of the IPMC actuator is correlated to its bending curvature. Experimental results on the relationship between actuating voltage, current and deformation are presented. It is shown that there are phase differences among these three variables. And it is further shown that within a certain range of deformation, there is a correlation between the impedance and the deformation. The findings suggest it is possible to design a novel way to detect the output feedback of IPMC actuator.

Abstract: The suspension kinematics and compliance (hereafter referred to as 'K & C') characteristics as the important system assembly characteristics have a direct effect on the vehicle handling and stability performance and the ride comfort performance. The suspension K&C test rig is an key equipment to obtain the suspension K&C characteristics. Calculation method of the target parameters of K&C test-rig is studied. The movement law of the suspension K & C test rig is analyzed by useing the multi-body dynamics theory. Application Space rotation transformation matrix based on the measurement system structure is applied to solve the coordinates of the wheel center. Using the space vector operations and the definition of the toe angle and the camber angle, the solution method of the camber and toe angle is derived. The parralel wheel travel analysis using the multi-body dynamics model of the K&C test rig is taken. The simulation results when the rebound travel is-100mm is used to calculate the target parameters and verify the accuracy of the calculation method.Keywords-K&C test; calculation method; multi-body dynamics; rotation transformation matrix;

Abstract: In this paper, a new approach based on the second-order statistics (SOS) and acoustic vector sensor (AVS) array is proposed, for localization estimation of near-field acoustic narrowband sources. Firstly, we choose the centrosymmetric uniform linear-array as the AVS arrangement, and the array is consistent with the coordinate axis direction of the acoustic vector-sensor. This estimation method makes good use of the acquisition information from the AVS, such as one-dimensional sound pressure and three-dimensional particle velocity, and has shown preferable performance for the parameter estimation of direction-of-arrival (DOA) and range of target acoustic sources in the near field. The estimation algorithm expands the near-field array manifold of one single acoustic vector sensor to the acoustic vector-sensor’s uniform linear-array, and the near-field acoustic vector sensor linear array output model is deduced. The autocorrelation and cross-correlation function of the velocity field and the pressure field are used to construct the rotational invariance frame, which helps to extract the expected information. Consequently, the closed-form solutions of the incident source’s DOA and range are derived explicitly through the parameter pairing operation. The proposed method reduces the computational burden and has good spatial recognition ability and high resolution in the case of limited array elements. It also has better engineering application prospect. Eventually, the performance of the method is verified by Monte Carlo simulation experiments.