Quadruped robots consume a lot of energy, which is one of the factors restricting their application. Energy efficiency is one of the key evaluating indicators for walking robots. The relationship between energy and el...Quadruped robots consume a lot of energy, which is one of the factors restricting their application. Energy efficiency is one of the key evaluating indicators for walking robots. The relationship between energy and elastic elements of walking robots have been studied, but different walking gait patterns and contact status have important influences on locomotion energy efficiency, and the energy efficiency considering the foot-end trajectory has not been reported. Therefore, the energy consumption and energy efficiency of quadruped robot with trot gait and combined cycloid foot trajectory are studied. The forward and inverse kinematics of quadruped robot is derived. The combined cycloid function is proposed to generate horizontal and vertical foot trajectory respectively, which can ensure the acceleration curve of the foot-end smoother and more successive, and reduce the contact force between feet and environment. Because of the variable topology mechanism characteristic of quadruped robot, the leg state is divided into three different phases which are swing phase, transition phase and stance phase during one trot gait cycle. The non-continuous variable constraint between feet and environment of quadruped robot is studied. The dynamic model of quadruped robot is derived considering the variable topology mechanism characteristic, the periodic contact and elastic elements of the robot. The total energy consumption of walking robot during one gait cycle is analyzed based on the dynamic model. The specific resistance is used to evaluate energy efficiency of quadruped robot. The calculation results show the relationships between specific resistance and gait parameters, which can be used to determine the reasonable gait parameters.展开更多
Developing efficient walking gaits for quadruped robots has intrigued investigators for years. Trot gait, as a fast locomotion gait, has been widely used in robot control. This paper follows the idea of the six determ...Developing efficient walking gaits for quadruped robots has intrigued investigators for years. Trot gait, as a fast locomotion gait, has been widely used in robot control. This paper follows the idea of the six determinants of gait and designs a trot gait for a parallel-leg quadruped robot, Baby Elephant. The walking period and step length are set as constants to maintain a relatively fast speed while changing different foot trajectories to test walking quality. Experiments show that kicking leg back improves body stability. Then, a steady and smooth trot gait is designed. Furthermore, inspired by Central Pattern Generators （CPG）, a series CPG model is proposed to achieve robust and dynamic trot gait. It is generally believed that CPG is capable of producing rhythmic movements, such as swimming, walking, and flying, even when isolated from brain and sensory inputs. The proposed CPG model, inspired by the series concept, can automatically learn the previous well-designed trot gait and reproduce it, and has the ability to change its walking frequency online as well. Experiments are done in real world to verify this method.展开更多
In order to enhance the dynamic motion capability of the bionic quadruped robot,a flying trot gait control method based on full-scale virtual model and optimal plantar force distribution is proposed.A stable flying tr...In order to enhance the dynamic motion capability of the bionic quadruped robot,a flying trot gait control method based on full-scale virtual model and optimal plantar force distribution is proposed.A stable flying trot gait is accomplished by mapping the robot torso motion to the foot trajectory.The force distribution calculated by the torso virtual model is converted into a quadratic optimization problem and solved in real time by the open source library Gurobi.The transition between the trot gait and the flying trot gait is achieved by coordinating leg motion phases.The results of the dynamic simulation verify that the proposed method can realize the 3D stable flying trot gait.Compared against the trot gait,the flying trot gait can improve the speed of the quadruped robot.Combine the trot gait and the flying trot gait,the quadruped robot can move efficiently and adapt to complex terrains.展开更多
Herein,a control method based on the optimal energy efficiency of a hydraulic quadruped robot was proposed,which not only realizes the optimal energy efficiency of flying trot gait but also ensures the stability of hi...Herein,a control method based on the optimal energy efficiency of a hydraulic quadruped robot was proposed,which not only realizes the optimal energy efficiency of flying trot gait but also ensures the stability of high-speed movement.Concretely,the energy consumption per unit distance was adopted as the energy efficiency evaluation index based on the constant pressure oil supply characteristics of the hydraulic system,and the global optimization algorithm was adopted to solve the optimal parameters.Afterward,the gait parameters that affect the energy efficiency of quadruped were analyzed and the mapping relationship between each parameter and energy efficiency was captured,so as to select the optimum combination of energy efficiency parameters,which is significant to improve endurance capability.Furthermore,to ensure the stability of the high-speed flying trot gait motion of the hydraulic quadruped robot,the active compliance control strategy was employed.Lastly,the proposed method was successfully verified by simulations and experiments.The experimental results reveal that the flying trot gait of the hydraulic quadruped robot can be stably controlled at a speed of 2.2 m/s.展开更多
This paper proposes a metamorphic quadruped robot with a moveable trunk, called Origaker I. From the angle view of bionics, the robot can imitate the natural quadrupeds to twist its trunk. As we all know, most natural...This paper proposes a metamorphic quadruped robot with a moveable trunk, called Origaker I. From the angle view of bionics, the robot can imitate the natural quadrupeds to twist its trunk. As we all know, most natural quadrupeds twist their trunk when running. The twisting trunk must bring significant benefits to their locomotion. Nevertheless there are few researches focusing on running gaits with twisting trunk of quadruped robots. Therefore, this paper investigates the trot gait with twisting trunk. One gait cycle of a lizard with twisting trunk is observed. Apart from the observation, the gait is designed based on the Zero Moment Point （ZMP） method and by con- sidering three points related to the twisting trunk. A simulation and an experiment are carried out to verify the efficiency of the trot gait with twisting trunk. It is found that the twisting trunk helps the quadruped robot get larger stride length and further perform higher lo- comotion speed than that with rigid trunk.展开更多
The dynamic stability of a quadruped robot trotting on slope was analyzed.Compared with crawl gait,trot gait can improve walking speed of quadruped robots.When a quadruped robot trots,each leg is in the alternate stat...The dynamic stability of a quadruped robot trotting on slope was analyzed.Compared with crawl gait,trot gait can improve walking speed of quadruped robots.When a quadruped robot trots,each leg is in the alternate state of swing phase or supporting phase,and two legs in the diagonal line are in the same phase.The feet in the supporting phase form a supporting region on the ground.When a quadruped robot walks on slope,the vertical distance from zero moment point(ZMP) to the supporting diagonal line is defined as ZMP offset distance.Whether this distance is less than the maximum offset distance or not,the stability of robot trotting on slope can be judged.The foot trajectory was planned with the sinusoidal function.Based on the kinematic analysis,the ZMP offset distance of quadruped robot under different slope angles,step length and step height was calculated,then the reasonable slope angle,step length and step height for quadruped robot trotting on slope to keep dynamic stability can be determined.On the other hand,the posture angle of quadruped robot should be controlled within the desired range.Computer simulations were executed to verify the theoretical analysis.The study will provide reference for determining reasonable step parameters of the quadruped robot.展开更多
基金supported by National Natural Science Foundation of China(Grant No.51375289)Shanghai Municipal National Natural Science Foundation of China(Grant No.13ZR1415500)Innovation Fund of Shanghai Education Commission of China(Grant No.13YZ020)
文摘Quadruped robots consume a lot of energy, which is one of the factors restricting their application. Energy efficiency is one of the key evaluating indicators for walking robots. The relationship between energy and elastic elements of walking robots have been studied, but different walking gait patterns and contact status have important influences on locomotion energy efficiency, and the energy efficiency considering the foot-end trajectory has not been reported. Therefore, the energy consumption and energy efficiency of quadruped robot with trot gait and combined cycloid foot trajectory are studied. The forward and inverse kinematics of quadruped robot is derived. The combined cycloid function is proposed to generate horizontal and vertical foot trajectory respectively, which can ensure the acceleration curve of the foot-end smoother and more successive, and reduce the contact force between feet and environment. Because of the variable topology mechanism characteristic of quadruped robot, the leg state is divided into three different phases which are swing phase, transition phase and stance phase during one trot gait cycle. The non-continuous variable constraint between feet and environment of quadruped robot is studied. The dynamic model of quadruped robot is derived considering the variable topology mechanism characteristic, the periodic contact and elastic elements of the robot. The total energy consumption of walking robot during one gait cycle is analyzed based on the dynamic model. The specific resistance is used to evaluate energy efficiency of quadruped robot. The calculation results show the relationships between specific resistance and gait parameters, which can be used to determine the reasonable gait parameters.
基金This research was supported by the National Basic Research Program of China，China Postdoctoral Science Foundation
文摘Developing efficient walking gaits for quadruped robots has intrigued investigators for years. Trot gait, as a fast locomotion gait, has been widely used in robot control. This paper follows the idea of the six determinants of gait and designs a trot gait for a parallel-leg quadruped robot, Baby Elephant. The walking period and step length are set as constants to maintain a relatively fast speed while changing different foot trajectories to test walking quality. Experiments show that kicking leg back improves body stability. Then, a steady and smooth trot gait is designed. Furthermore, inspired by Central Pattern Generators （CPG）, a series CPG model is proposed to achieve robust and dynamic trot gait. It is generally believed that CPG is capable of producing rhythmic movements, such as swimming, walking, and flying, even when isolated from brain and sensory inputs. The proposed CPG model, inspired by the series concept, can automatically learn the previous well-designed trot gait and reproduce it, and has the ability to change its walking frequency online as well. Experiments are done in real world to verify this method.
基金This work was supported by the National Key R&D Program of China(Grant No.2017YFC0806505)the National High-tech R&D Program of China(Grant No.2015AA042201)+1 种基金National Natural Science Foundation of China(Grant Nos.U1613223 and 61603216)the Key R&D Program of Shandong(Grant No.2017CXGC0901).
文摘In order to enhance the dynamic motion capability of the bionic quadruped robot,a flying trot gait control method based on full-scale virtual model and optimal plantar force distribution is proposed.A stable flying trot gait is accomplished by mapping the robot torso motion to the foot trajectory.The force distribution calculated by the torso virtual model is converted into a quadratic optimization problem and solved in real time by the open source library Gurobi.The transition between the trot gait and the flying trot gait is achieved by coordinating leg motion phases.The results of the dynamic simulation verify that the proposed method can realize the 3D stable flying trot gait.Compared against the trot gait,the flying trot gait can improve the speed of the quadruped robot.Combine the trot gait and the flying trot gait,the quadruped robot can move efficiently and adapt to complex terrains.
文摘Herein,a control method based on the optimal energy efficiency of a hydraulic quadruped robot was proposed,which not only realizes the optimal energy efficiency of flying trot gait but also ensures the stability of high-speed movement.Concretely,the energy consumption per unit distance was adopted as the energy efficiency evaluation index based on the constant pressure oil supply characteristics of the hydraulic system,and the global optimization algorithm was adopted to solve the optimal parameters.Afterward,the gait parameters that affect the energy efficiency of quadruped were analyzed and the mapping relationship between each parameter and energy efficiency was captured,so as to select the optimum combination of energy efficiency parameters,which is significant to improve endurance capability.Furthermore,to ensure the stability of the high-speed flying trot gait motion of the hydraulic quadruped robot,the active compliance control strategy was employed.Lastly,the proposed method was successfully verified by simulations and experiments.The experimental results reveal that the flying trot gait of the hydraulic quadruped robot can be stably controlled at a speed of 2.2 m/s.
基金This work was supported by the Natural Science Foundation of China （Project Nos. 51535008 and 51721003） and the Talent Scheme under Grant No. B 16034.
文摘This paper proposes a metamorphic quadruped robot with a moveable trunk, called Origaker I. From the angle view of bionics, the robot can imitate the natural quadrupeds to twist its trunk. As we all know, most natural quadrupeds twist their trunk when running. The twisting trunk must bring significant benefits to their locomotion. Nevertheless there are few researches focusing on running gaits with twisting trunk of quadruped robots. Therefore, this paper investigates the trot gait with twisting trunk. One gait cycle of a lizard with twisting trunk is observed. Apart from the observation, the gait is designed based on the Zero Moment Point （ZMP） method and by con- sidering three points related to the twisting trunk. A simulation and an experiment are carried out to verify the efficiency of the trot gait with twisting trunk. It is found that the twisting trunk helps the quadruped robot get larger stride length and further perform higher lo- comotion speed than that with rigid trunk.
基金Supported by the National Natural Science Foundation of China(No.51375289)Shanghai Municipal National Natural Science Foundation of China(No.13ZR1415500)Innovation Fund of Shanghai Education Commission(No.13YZ020)
文摘The dynamic stability of a quadruped robot trotting on slope was analyzed.Compared with crawl gait,trot gait can improve walking speed of quadruped robots.When a quadruped robot trots,each leg is in the alternate state of swing phase or supporting phase,and two legs in the diagonal line are in the same phase.The feet in the supporting phase form a supporting region on the ground.When a quadruped robot walks on slope,the vertical distance from zero moment point(ZMP) to the supporting diagonal line is defined as ZMP offset distance.Whether this distance is less than the maximum offset distance or not,the stability of robot trotting on slope can be judged.The foot trajectory was planned with the sinusoidal function.Based on the kinematic analysis,the ZMP offset distance of quadruped robot under different slope angles,step length and step height was calculated,then the reasonable slope angle,step length and step height for quadruped robot trotting on slope to keep dynamic stability can be determined.On the other hand,the posture angle of quadruped robot should be controlled within the desired range.Computer simulations were executed to verify the theoretical analysis.The study will provide reference for determining reasonable step parameters of the quadruped robot.
