Optimization of a Planar Quadruped Dynamic Leap

2008 ◽  
Author(s):  
Subhrajit Bhattacharya ◽  
Sachin Chitta ◽  
Vijay Kumar ◽  
Daniel Lee
Keyword(s):  
Quadruped Robot ◽  
Experimental Results ◽  
Walking Robots ◽  
Rough Terrain

Quadruped walking robots need to handle high obstacles like steps that are often not kinematically reachable. We present a dynamic leap that allows a quadruped robot to put its front legs up onto a high rock or ledge, a motion we have found is critical to being able to locomote over rough terrain. The leaping motion was optimized using a simulated planar quadruped model. We present experimental results for the implementation of this optimized motion on a real quadruped robot.

Design of a Four Legged Parallel Mechanism to Improve the Dexterity of Walking Robot

2009 ◽  
Author(s):  
ChiHyo Kim ◽  
KunWoo Park ◽  
TaeSung Kim ◽  
MinKi Lee
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Jacobian Matrix ◽  
Topology Design ◽  
Condition Numbers ◽  
Walking Robots ◽  
Rough Terrain ◽  
Parallel Mechanisms ◽  
Walking Robot ◽  
Intermediate Mechanism

This paper designs a four legged parallel mechanism to improve the dexterity of three layered parallel walking robot. Topology design is conducted for a leg mechanism composed of four legs, base and ground, which constitute a redundant parallel mechanism. This mechanism is subdivided into four sub-mechanism composed of three legs. A motor vector is adopted to determine the 6×8 Jacobian of the redundant parallel mechanism and the 6×6 Jacobian of the sub-mechanisms, respectively. The condition number of the Jacobian matrix is used as an index to measure a dexterity. We analyze the condition numbers of the Jacobian over the positional and orientational walking space. The analytical results show that a sub-mechanism has lots of singularities within workspace but they are removed by a redundant parallel mechanism improving the dexterity. This paper presents a parallel typed walking robot to enlarge walking space and stability region. Seven types of three layered walking robots are designed by inserting an intermediate mechanism between the upper and the lower legged parallel mechanisms. They provide various types of gaits to walk rough terrain and climb over a wall with small degrees of freedom.

scholarly journals Learning the Cost Function for Foothold Selection in a Quadruped Robot

Sensors ◽  
2019 ◽  
Vol 19 (6) ◽  
pp. 1292 ◽  
Author(s):  
Xingdong Li ◽  
Hewei Gao ◽  
Fusheng Zha ◽  
Jian Li ◽  
Yangwei Wang ◽  
...  
Keyword(s):  
Cost Function ◽  
Weight Vector ◽  
Quadruped Robot ◽  
Training Data ◽  
Rough Terrain ◽  
Weighted Sum ◽  
Data Set ◽  
Tof Camera ◽  
The Cost ◽  
Terrain Features

This paper is focused on designing a cost function of selecting a foothold for a physical quadruped robot walking on rough terrain. The quadruped robot is modeled with Denavit–Hartenberg (DH) parameters, and then a default foothold is defined based on the model. Time of Flight (TOF) camera is used to perceive terrain information and construct a 2.5D elevation map, on which the terrain features are detected. The cost function is defined as the weighted sum of several elements including terrain features and some features on the relative pose between the default foothold and other candidates. It is nearly impossible to hand-code the weight vector of the function, so the weights are learned using Supporting Vector Machine (SVM) techniques, and the training data set is generated from the 2.5D elevation map of a real terrain under the guidance of experts. Four candidate footholds around the default foothold are randomly sampled, and the expert gives the order of such four candidates by rotating and scaling the view for seeing clearly. Lastly, the learned cost function is used to select a suitable foothold and drive the quadruped robot to walk autonomously across the rough terrain with wooden steps. Comparing to the approach with the original standard static gait, the proposed cost function shows better performance.

Implementation of a Quadruped Robot Pronking/Bounding Gait Using a Multipart Controller

2010 ◽  
Author(s):  
Alexandros Nikolakakis ◽  
Ioannis Kontolatis ◽  
Nicholas Cherouvim ◽  
Panagiotis Chatzakos ◽  
Evangelos Papadopoulos
Keyword(s):  
High Speed ◽  
Quadruped Robot ◽  
Experimental Results ◽  
High Speed Camera ◽  
Apex Height ◽  
Bounding Gait

This paper presents a multipart pronking/bounding controller for a quadruped robot, as well as the corresponding experimental results. The controller achieves given apex height and forward velocity in a quadruped robot with only one actuator per leg. A quadruped is designed and built and described in some detail. Experimental results obtained using internal sensors and high-speed camera captions show that the implemented quadruped robot performs pronking gaits and achieves bounding gaits with the desired characteristics.

Normalized Energy Stability Margin Based Analysis of Omni-Directional Static Walking of a Quadruped Robot on Rough Terrain

2011 ◽  
Vol 383-390 ◽  
pp. 7401-7405
Author(s):  
Lei Zhang ◽  
Shan Gao
Keyword(s):  
Stability Criterion ◽  
Simulation Experiment ◽  
Stability Margin ◽  
Quadruped Robot ◽  
Center Of Gravity ◽  
Energy Stability ◽  
Rough Terrain ◽  
The Stability

With Normalized Energy Stability Margin(Sne ) as stability criterion, this paper studies the tumbles of omni-directional static walking of a quadruped robot around the line connecting two adjacent supporting legs on rough terrain, proposes the method to improve the stability of quadruped robot by increasing the (Sne ) value, which is realized by lowering the height of center of gravity(COG), and finally substantiates the feasibility of the method through a simulation experiment.

scholarly journals Self-Stabilising Quadrupedal Running by Mechanical Design

2009 ◽  
Vol 6 (1) ◽  
pp. 73-85 ◽  
Author(s):  
Panagiotis Chatzakos ◽  
Evangelos Papadopoulos
Keyword(s):  
Mechanical System ◽  
Mechanical Design ◽  
Quadruped Robot ◽  
The Self ◽  
Rough Terrain ◽  
Stable Regime ◽  
Quadruped Robots ◽  
The Stability ◽  
Running Robots ◽  
Body Inertia

Dynamic stability allows running animals to maintain preferred speed during locomotion over rough terrain. It appears that rapid disturbance rejection is an emergent property of the mechanical system. In running robots, simple motor control seems to be effective in the negotiation of rough terrain when used in concert with a mechanical system that stabilises passively. Spring-like legs are a means for providing self-stabilising characteristics against external perturbations. In this paper, we show that a quadruped robot could be able to perform self-stable running behaviour in significantly broader ranges of forward speed and pitch rate with a suitable mechanical design, which is not limited to choosing legs spring stiffness only. The results presented here are derived by studying the stability of the passive dynamics of a quadruped robot running in the sagittal plane in a dimensionless context and might explain the success of simple, open loop running controllers on existing experimental quadruped robots. These can be summarised in (a) the self-stabilised behaviour of a quadruped robot for a particular gait is greatly related to the magnitude of its dimensionless body inertia, (b) the values of hip separation, normalised to rest leg length, and leg relative stiffness of a quadruped robot affect the stability of its motion and should be in inverse proportion to its dimensionless body inertia, and (c) the self-stable regime of quadruped running robots is enlarged at relatively high forward speeds. We anticipate the proposed guidelines to assist in the design of new, and modifications of existing, quadruped robots. As an example, specific design changes for the Scout II quadruped robot that might improve its performance are proposed.

Steering a quadruped robot: Simulation and experimental results

2014 ◽  
Author(s):  
Alessandro Paolone de Medeiros ◽  
Jeeves Lopes dos Santos ◽  
Cairo Lucio Nascimento Junior
Keyword(s):  
Quadruped Robot ◽  
Experimental Results ◽  
Robot Simulation

scholarly journals Hierarchically Planning Static Gait for Quadruped Robot Walking on Rough Terrain

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Xingdong Li ◽  
Hewei Gao ◽  
Jian Li ◽  
Yangwei Wang ◽  
Yanling Guo
Keyword(s):  
Hierarchical Structure ◽  
Classical Model ◽  
Quadruped Robot ◽  
Rough Terrain ◽  
Simulation Environment ◽  
Terrain Features ◽  
2D Space ◽  
Robot Body

Quadruped robot has great potential to walk on rough terrain, in which static gait is preferred. A hierarchical structure based controlling algorithm is proposed in this paper, in which trajectory of robot center is searched, and then static gaits are generated along such trajectory. Firstly, cost map is constructed by computing terrain features under robot body and cost of selecting footholds at default positions, and then the trajectory of robot center in 2D space is searched using heuristic A⁎ algorithm. Secondly, robot state is defined from foothold and robot pose, and then state series are searched recursively along the trajectory of robot center to generate static gaits, where a tree-like structure is used to store such states. Lastly, a classical model for quadruped robot is designed, and then the controlling algorithm proposed in the paper is demonstrated on such robot model for both structured terrain and complex unstructured terrain in a simulation environment.

scholarly journals Static Gait Planning Method for Quadruped Robot Walking on Unknown Rough Terrain

IEEE Access ◽  
2019 ◽  
Vol 7 ◽  
pp. 177651-177660 ◽  
Author(s):  
Shuaishuai Zhang ◽  
Ming Liu ◽  
Yanfang Yin ◽  
Xuewen Rong ◽  
Yibin Li ◽  
...  
Keyword(s):  
Quadruped Robot ◽  
Planning Method ◽  
Rough Terrain ◽  
Gait Planning

Design of Vertebrae-Inspired Trunk Mechanism for Robust and Directive Quadruped Locomotion on Rough Terrain Without Requiring Sensing and Actuation

2017 ◽  
Vol 29 (3) ◽  
pp. 546-555 ◽  
Author(s):  
Takashi Takuma ◽  
◽  
Yoshiki Murata ◽  
Wataru Kase
Keyword(s):  
Rigid Body ◽  
Success Rate ◽  
Design Principle ◽  
Quadruped Robot ◽  
Rough Terrain ◽  
Elastic Coefficient ◽  
Sensors And Actuators ◽  
Quadruped Locomotion ◽  
Trunk Posture ◽  
Simulation Results

[abstFig src='/00290003/10.jpg' width='300' text='Quadruped robot equipping a vertebrae-inspired trunk mechanism' ] Quadrupedal animals adaptively change their trunk posture in order to avoid falling down and to facilitate directive locomotion even on rough terrain. This paper focuses on an animal-like trunk mechanism which has passive viscoelastic joints. The effect of the trunk mechanism is observed by changing the elasticity and configuration of joints. Simulation results showed that the locomotion success rate of a robot equipped with the trunk mechanism on rough terrain is higher than the locomotion success rate of a robot equipped with a rigid body. In addition, the distribution of the success rate changes according to the elastic coefficient, number, configuration, and type of joints. These results suggest a design principle for the trunk mechanism of a quadruped robot in order to obtain robust and directive locomotion without requiring sensors and actuators.

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