“…56 Due to the similarity between the biped robot and the human locomotion, some important aspects should be considered in order to generate natural biped locomotion, which are as follows 107 : r Learning (training), which needs a certain level of intelligence. r A high level of adaptability to cope with uneven terrains and external disturbances.…”
Section: Walking Pattern Generatorsmentioning
“…One of the important issues of the biped locomotion is the generation of the desired paths that ensure stability while avoiding collision with obstacles. 56 Due to the similarity between the biped robot and the human locomotion, some important aspects should be considered in order to generate natural biped locomotion, which are as follows 107 :…”
Section: Walking Pattern Generatorsmentioning
“…109 Examples of methods used to compensate ZMP online include preview control, 110 model predictive control, 109,111,112 and AIbased gait. 56,113 In general, the model-based methods can give useful explanations about the behavior of human walking. In contrast, AI can give robust results without explanation.…”
Biped robots have gained much attention for decades. A variety of researches have been conducted to make them able to assist or even substitute for humans in performing special tasks. In addition, studying biped robots is important in order to understand human locomotion and to develop and improve control strategies for prosthetic and orthotic limbs. This paper discusses the main challenges encountered in the design of biped robots, such as modeling, stability and their walking patterns. The subject is difficult to deal with because the biped mechanism intervenes with mechanics, control, electronics and artificial intelligence. In this paper, we collect and introduce a systematic discussion of modeling, walking pattern generators and stability for a biped robot.
“…If the minimum energy is required, the literature prefers the actuating torque cost on the energetic cost due to the instability problems of the latter. If the designer intends to focus on the best stability of the biped mechanism, the minimum deviation of ZMP can be used as cost function . The latter reference has used combined cost function of the sum of the deviation of ZMP and the minimum energy.…”
Section: Dynamic Optimization Of 6-dof Biped Robotmentioning
Abstract-This paper concentrates on three important points: the selection of the suitable direct method used for suboptimal control of the biped robot, the selection of the appropriate nonlinear programming (NLP) algorithm that searches for the global minimum rather than the local minimum, and the effect of different constraints on the energy of the biped robot. To perform the mentioned points, the advantages and disadvantages of the optimal control methods were illustrated. The inverse-dynamics based optimization is preferred because of the ability to convert the original optimal control into algebraic equations which are easy to deal with. The inverse-dynamics-based optimization was classified as spline and the finite difference based optimization. Due to the easy use of the latter, it was used for investigating seven cases with different constraints for 6-DOF biped robot during the single support phase (SSP). Hybrid genetic-sequential quadratic programming (GA-SQP) was used for simulation of the target robot with MATLAB. It can be concluded that more imposed constraints on the biped robot, more energy is needed. In general, more energy can be required in the case of (1) restriction of the swing foot to be level to the ground and (2) reducing the hip height or constraining the hip to move in constant height.Index Terms-Biped robot, dynamic optimization suboptimal control, walking patterns.
“…One of the important issues of the biped locomotion is the generation of the desired paths that ensure stability and avoid collision with obstacles . Numerous approaches have been used to generate the motion of the biped robot as detailed in .…”
Abstract-One of the clear problems encountered in the dynamic response of the biped robot is the discontinuity of the actuating torques/ground reaction forces at the transition instances during transferring form single support phase to double support phase and vice versa. Therefore, this paper suggests the linear transition function used in the biomechanics field for estimating the ground reaction forces during the double support phase such that gradual increase/decrease of the ground reaction forces can occur. The closure loop of the biped robot at the transition instances during DSP can be broken using the mentioned strategy. Consequently, the continuous dynamic response can be achieved. Two cases are simulated using the optimal control theory. The inverse dynamics-based optimization is preferred as a direct suboptimal tool because it can show less computation and easinessthan other optimal control approaches. Due to easiness of the finite difference approach, it is used for discretization of the dynamic equations and the imposed constraints to convert the dynamic optimal control problem into parameter optimization. The simulated case 1 have been used repeatedly in the literature, whereas the case 2 adopts the linear transition function of the ground reaction forces keeping the same generalized coordinates of the biped configuration at the transition instances. The results show the superiority of the suggested method to guarantee continuous actuating torques/ground reaction forces at the transition instances.
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