Gait synthesis for a three-legged robot using Learning Automata

Santos, Jeeves Lopes dos; Nascimento, Cairo Lúcio

doi:10.1109/icar.2011.6088586

Cited by 4 publications

(3 citation statements)

References 10 publications

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“…Crucially, minimizing the number of legs reduces the total weight of the robot, and may thus benefit agility during locomotion and allows for a better performance-weight-ratio. For reference, other three-legged designs were proposed in the literature [1], [10], [24], [26], [60], [62], [66], [68], [70]; however, those have largely different properties and target applications, as discussed in [33]. Similarly, the serialparallel (II) actuation layout is an important property, which features a 3-degrees-of-freedom (DOF) motion of the hip joints via a spherical parallel mechanism, and a 1-DOF knee joint, connected in series.…”

Section: A the Robot Conceptmentioning

confidence: 99%

Kinematics of a Novel Serial-Parallel, Compliant, Three-Legged Robot

Feller

2023

IEEE Access

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In this article, the solution to the inverse and forward kinematics of a novel three-legged, serialparallel, compliant robot are presented. The design of the robot aims to combine properties from serial and parallel architectures, thereby targeting an agile, yet precisely controllable robot that possibly allows both for dynamic locomotion and accurate manipulation tasks. The robot embodies the series connection of two parallel architectures, a planar and a spherical mechanism, realized in a highly dense mechanical assembly, allowing for lightweight, functionally redundant and compliant 4-DOF legs. A hybrid compliance behaviour is achieved, serving as a threshold between a stiff and compliant systemic state of the robot. Based on the mechanism design, the study involves the derivation of an alternative, yet complete solution for the inverse and forward kinematics of the spherical parallel manipulator (SPM). The approach utilizes spherical trigonometry and spatial vector geometry and yields a unique solution, while being both easy to implement and numerically efficient, thereby being applicable to real time implementations. Conceptually, a reduction of the mechanism assembly and working modes was directly integrated into the solution terms, drastically simplifying the expressions as they only represents the mechanically meaningful configuration relevant for actual physical systems. In addition to the active joint coordinates, the solution yields a unique set of all passively driven joints. The derived robot kinematics are furthermore verified through a 3D simulation model, showing the robot performing several motions. Thereby, the simulations portray the characteristics of the motor units by means of their corresponding phase profiles, revealing a balanced utilisation.INDEX TERMS Forward kinematics, inverse kinematics, legged robot, mechanical design, serial-parallel mechanism, spherical parallel manipulator.

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Section: A the Robot Conceptmentioning

confidence: 99%

Kinematics of a Novel Serial-Parallel, Compliant, Three-Legged Robot

Feller

2023

IEEE Access

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“…Although only a single case is presented in this article, the proposed method has also been successfully applied to nonhybrid legged robots with 2, 3 and 4 legs [6] [7] [8] [9]. Some possible directions for further work are:…”

Section: Conclusion and Further Workmentioning

confidence: 99%

“…Estimation of the probability of success for the selected solution is calculated by assigning a reinforcement signal R whose value is determined by (A.1), where R c is the calculated reinforcement signal and R G corresponds to the maximum value (a parameter set by the designer) which R c should be [7]. …”

Section: Appendixmentioning

confidence: 99%

Gait synthesis of a hybrid legged robot using reinforcement learning

Santos

Nascimento

2015

2015 Annual IEEE Systems Conference (SysCon) Proceedings

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This article is concerned with the gait synthesis problem of a hybrid robot (in this case, a four-legged robot with free wheels on its feet) considering multiple criteria. It is assumed that the position of each leg actuator over time is described by a periodic function with parameters that are determined using the learning automata reinforcement learning algorithm. Analysis of the robot morphology is used to group similar legs and decrease the number of actuator functions that must be determined. MATLAB/Simulink/SimMechanics Toolbox are used to simulate the robot gait. The simulated robot response is evaluated by the reinforcement learning algorithm considering: 1) the robot frontal speed, 2) the "smoothness" of the robot movements, 3) the largest torque required by all leg actuators, and 4) the robot energy consumption. When the reinforcement learning algorithm converges to a good solution, it is applied to the real robot which was built using the Bioloid Comprehensive Kit, an educational robot kit manufactured by ROBOTIS. The responses of the simulated and real robot are then compared and are shown to be similar.

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Dexterity, Workspace and Performance Analysis of the Conceptual Design of a Novel Three-legged, Redundant, Lightweight, Compliant, Serial-parallel Robot

Feller

2023

J Intell Robot Syst

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In this article, the mechanical design and analysis of a novel three-legged, agile robot with passively compliant 4-degrees-of-freedom legs, comprising a hybrid topology of serial, planar and spherical parallel structures, is presented. The design aims to combine the established principle of the Spring Loaded Inverted Pendulum model for energy efficient locomotion with the accuracy and strength of parallel mechanisms for manipulation tasks. The study involves several kinematics and Jacobian based analyses that specifically evaluate the application of a non-overconstrained spherical parallel manipulator as a robot hip joint, decoupling impact forces and actuation torques, suitable for the requirements of legged locomotion. The dexterity is investigated with respect to joint limits and workspace boundary contours, showing that the mechanism stays well conditioned and allows for a sufficient range of motion. Based on the functional redundancy of the constrained serial-parallel architecture it is furthermore revealed that the robot allows for the exploitation of optimal leg postures, resulting in the possible optimization of actuator load distribution and accuracy improvements. Consequently, the workspace of the robot torso as additional end-effector is investigated for the possible application of object manipulation tasks. Results reveal the existence of a sufficient volume applicable for spatial motion of the torso in the statically stable tripodal posture. In addition, a critical load estimation is derived, which yields a posture dependent performance index that evaluates the risks of overload situations for the individual actuators.

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Gait synthesis for a three-legged robot using Learning Automata

Cited by 4 publications

References 10 publications

Kinematics of a Novel Serial-Parallel, Compliant, Three-Legged Robot

Kinematics of a Novel Serial-Parallel, Compliant, Three-Legged Robot

Gait synthesis of a hybrid legged robot using reinforcement learning

Dexterity, Workspace and Performance Analysis of the Conceptual Design of a Novel Three-legged, Redundant, Lightweight, Compliant, Serial-parallel Robot

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