Many daily tasks involve spatio-temporal coordination between two agents. Study of such coordinat... more Many daily tasks involve spatio-temporal coordination between two agents. Study of such coordinated actions in human-human and human-robot interaction has received increased attention of late. In this work, we use the mirror paradigm to study coupling of hand motion in a leader-follower game. The main aim of this study is to model the motion of the follower, given a particular motion of the leader. We propose a mathematical model consistent with the internal model hypothesis and the delays in the sensorimotor system. A qualitative comparison of data collected in four human dyads shows that it is possible to successfully model the motion of the follower.
Introduction Within the field of quadruped robot research, much focus has been put on design of l... more Introduction Within the field of quadruped robot research, much focus has been put on design of leg compliance and leg configuration , and controller design . Typically, design goals include robot speed, cost of transport, robustness against perturbations, and range of available speeds. Recently, research has started mimicking the spine of quadruped animals, both in the frontal and the sagittal plane. A widely accepted hypothesis predicts higher speed, resulting from active spine motion. Here we present results from hardware experiments with an active-spine equipped quadruped bounding robot, showing that through reduction of horizontal impulse the robot's mechanical cost of transport was reduced.
Proceedings of 2014 Ieee International Conference on Robotics and Automation, May 31, 2014
We present a data-driven method for designing parallel compliance. Designing such compliance help... more We present a data-driven method for designing parallel compliance. Designing such compliance helps the system to improve energy efficiency, mainly by reducing negative work. The core idea is to design a controller first and then find springs working in parallel with each actuator such that forcedisplacement graph is lined up around displacement axis. By doing so, we simply shape the natural dynamics for performing the task efficiently. Maximum torque reduction for actuators is a byproduct of this design method. The method can be used in different cyclic robotic application, especially in legged locomotion systems. In this paper, we design a spinal compliance for a bounding quadruped robot in Webots. The results show that the power consumption and the maximum torque are reduced significantly.
1 Introduction Having a direct impact on the energy efficiency has made the compliance a favorabl... more 1 Introduction Having a direct impact on the energy efficiency has made the compliance a favorable element in the robotic systems. Moreover, legged system can benefit from compliance for stability, speed, adaptability and robustness. Recently, we have studied the effects of compliant spine in quadrupedal robots. We have observed that having nonlinearity in the spine compliance can set a better trade-off between speed and energy efficiency; see . Similar to the spine in quadruped robots, compliance at the hip joint of bipedal robots can also improve the walking performance such as robustness; see . Here, we test the efficacy of piecewise linear hip compliance for robust bipedal walking.
2014 IEEE International Conference on Systems, Man, and Cybernetics (SMC), 2014
Many daily tasks involve spatio-temporal coordination between two agents. Study of such coordinat... more Many daily tasks involve spatio-temporal coordination between two agents. Study of such coordinated actions in human-human and human-robot interaction has received increased attention of late. In this work, we use the mirror paradigm to study coupling of hand motion in a leader-follower game. The main aim of this study is to model the motion of the follower, given a particular motion of the leader. We propose a mathematical model consistent with the internal model hypothesis and the delays in the sensorimotor system. A qualitative comparison of data collected in four human dyads shows that it is possible to successfully model the motion of the follower.
2014 IEEE International Conference on Robotics and Automation (ICRA), 2014
We present a data-driven method for designing parallel compliance. Designing such compliance help... more We present a data-driven method for designing parallel compliance. Designing such compliance helps the system to improve energy efficiency, mainly by reducing negative work. The core idea is to design a controller first and then find springs working in parallel with each actuator such that forcedisplacement graph is lined up around displacement axis. By doing so, we simply shape the natural dynamics for performing the task efficiently. Maximum torque reduction for actuators is a byproduct of this design method. The method can be used in different cyclic robotic application, especially in legged locomotion systems. In this paper, we design a spinal compliance for a bounding quadruped robot in Webots. The results show that the power consumption and the maximum torque are reduced significantly.
ABSTRACT Compliance became the essential part of locomotion in robotics. Due to ability of storin... more ABSTRACT Compliance became the essential part of locomotion in robotics. Due to ability of storing and releasing energy, compliance can be used for energy efficiency or reducing impact during ground collision and gaining robustness. On the other side, natural/passive dynamics are important because by exploiting such dynamics, energy efficiency will be assured. Therefore it is crucial to understand how compliance changes natural dynamics of a system. After this inspection, natural dynamics exploitation can be more straightforward through developing tools like adaptive oscillators.
Introduction Within the field of quadruped robot research, much focus has been put on design of l... more Introduction Within the field of quadruped robot research, much focus has been put on design of leg compliance and leg configuration , and controller design . Typically, design goals include robot speed, cost of transport, robustness against perturbations, and range of available speeds. Recently, research has started mimicking the spine of quadruped animals, both in the frontal and the sagittal plane. A widely accepted hypothesis predicts higher speed, resulting from active spine motion. Here we present results from hardware experiments with an active-spine equipped quadruped bounding robot, showing that through reduction of horizontal impulse the robot's mechanical cost of transport was reduced.
We studied the effect of the control of an active spine versus a fixed spine, on a quadruped robo... more We studied the effect of the control of an active spine versus a fixed spine, on a quadruped robot running in bound gait. Active spine supported actuation led to faster locomotion, with less foot sliding on the ground, and a higher stability to go straight forward. However, we did no observe an improvement of cost of transport of the spine-actuated, faster robot system compared to the rigid spine.
ABSTRACT We compare the effects of linear and piecewise linear compliant spines on locomotion per... more ABSTRACT We compare the effects of linear and piecewise linear compliant spines on locomotion performance of quadruped robots in terms of energy efficiency and locomotion speed through a set of simulations and experiments. We first present a simple locomotion system that behaviorally resembles a bounding quadruped with flexible spine. Then, we show that robots with linear compliant spines have higher locomotion speed and lower cost of transportation in comparison with those with rigid spine. However, in linear case, optimal speed and minimum cost of transportation are attained at very different spine compliance values. Moreover, it is verified that fast and energy efficient locomotion can be achieved together when the spine flexibility is piecewise linear. Furthermore, it is shown that the robot with piecewise linear spine is more robust against changes in the load it carries. Superiority of piecewise linear spines over linear and rigid ones is additionally confirmed by simulating a quadruped robot in Webots and experiments on a crawling two-parts robot with flexible connection.
The ability to follow one another’s gaze plays an important role in our social cognition; especi... more The ability to follow one another’s gaze plays an important role in our social cognition; especially when we synchronously perform tasks together. We investigate how gaze cues can improve performance in a simple coordination task (i.e., the mirror game), whereby two players mirror each other’s hand motions. In this game, each player is either a leader or follower. To study the effect of gaze in a systematic manner, the leader’s role is played by a robotic avatar. We contrast two conditions, in which the avatar provides or not explicit gaze cues that indicate the next location of its hand. Specifically, we investigated (a) whether participants are able to exploit these gaze cues to improve their coordination, (b) how gaze cues affect action prediction and temporal coordination, and (c) whether introducing active gaze behavior for avatars makes them more realistic and human-like (from the user point of view).
Many daily tasks involve spatio-temporal coordination between two agents. Study of such coordinat... more Many daily tasks involve spatio-temporal coordination between two agents. Study of such coordinated actions in human-human and human-robot interaction has received increased attention of late. In this work, we use the mirror paradigm to study coupling of hand motion in a leader-follower game. The main aim of this study is to model the motion of the follower, given a particular motion of the leader. We propose a mathematical model consistent with the internal model hypothesis and the delays in the sensorimotor system. A qualitative comparison of data collected in four human dyads shows that it is possible to successfully model the motion of the follower.
Introduction Within the field of quadruped robot research, much focus has been put on design of l... more Introduction Within the field of quadruped robot research, much focus has been put on design of leg compliance and leg configuration , and controller design . Typically, design goals include robot speed, cost of transport, robustness against perturbations, and range of available speeds. Recently, research has started mimicking the spine of quadruped animals, both in the frontal and the sagittal plane. A widely accepted hypothesis predicts higher speed, resulting from active spine motion. Here we present results from hardware experiments with an active-spine equipped quadruped bounding robot, showing that through reduction of horizontal impulse the robot's mechanical cost of transport was reduced.
Proceedings of 2014 Ieee International Conference on Robotics and Automation, May 31, 2014
We present a data-driven method for designing parallel compliance. Designing such compliance help... more We present a data-driven method for designing parallel compliance. Designing such compliance helps the system to improve energy efficiency, mainly by reducing negative work. The core idea is to design a controller first and then find springs working in parallel with each actuator such that forcedisplacement graph is lined up around displacement axis. By doing so, we simply shape the natural dynamics for performing the task efficiently. Maximum torque reduction for actuators is a byproduct of this design method. The method can be used in different cyclic robotic application, especially in legged locomotion systems. In this paper, we design a spinal compliance for a bounding quadruped robot in Webots. The results show that the power consumption and the maximum torque are reduced significantly.
1 Introduction Having a direct impact on the energy efficiency has made the compliance a favorabl... more 1 Introduction Having a direct impact on the energy efficiency has made the compliance a favorable element in the robotic systems. Moreover, legged system can benefit from compliance for stability, speed, adaptability and robustness. Recently, we have studied the effects of compliant spine in quadrupedal robots. We have observed that having nonlinearity in the spine compliance can set a better trade-off between speed and energy efficiency; see . Similar to the spine in quadruped robots, compliance at the hip joint of bipedal robots can also improve the walking performance such as robustness; see . Here, we test the efficacy of piecewise linear hip compliance for robust bipedal walking.
2014 IEEE International Conference on Systems, Man, and Cybernetics (SMC), 2014
Many daily tasks involve spatio-temporal coordination between two agents. Study of such coordinat... more Many daily tasks involve spatio-temporal coordination between two agents. Study of such coordinated actions in human-human and human-robot interaction has received increased attention of late. In this work, we use the mirror paradigm to study coupling of hand motion in a leader-follower game. The main aim of this study is to model the motion of the follower, given a particular motion of the leader. We propose a mathematical model consistent with the internal model hypothesis and the delays in the sensorimotor system. A qualitative comparison of data collected in four human dyads shows that it is possible to successfully model the motion of the follower.
2014 IEEE International Conference on Robotics and Automation (ICRA), 2014
We present a data-driven method for designing parallel compliance. Designing such compliance help... more We present a data-driven method for designing parallel compliance. Designing such compliance helps the system to improve energy efficiency, mainly by reducing negative work. The core idea is to design a controller first and then find springs working in parallel with each actuator such that forcedisplacement graph is lined up around displacement axis. By doing so, we simply shape the natural dynamics for performing the task efficiently. Maximum torque reduction for actuators is a byproduct of this design method. The method can be used in different cyclic robotic application, especially in legged locomotion systems. In this paper, we design a spinal compliance for a bounding quadruped robot in Webots. The results show that the power consumption and the maximum torque are reduced significantly.
ABSTRACT Compliance became the essential part of locomotion in robotics. Due to ability of storin... more ABSTRACT Compliance became the essential part of locomotion in robotics. Due to ability of storing and releasing energy, compliance can be used for energy efficiency or reducing impact during ground collision and gaining robustness. On the other side, natural/passive dynamics are important because by exploiting such dynamics, energy efficiency will be assured. Therefore it is crucial to understand how compliance changes natural dynamics of a system. After this inspection, natural dynamics exploitation can be more straightforward through developing tools like adaptive oscillators.
Introduction Within the field of quadruped robot research, much focus has been put on design of l... more Introduction Within the field of quadruped robot research, much focus has been put on design of leg compliance and leg configuration , and controller design . Typically, design goals include robot speed, cost of transport, robustness against perturbations, and range of available speeds. Recently, research has started mimicking the spine of quadruped animals, both in the frontal and the sagittal plane. A widely accepted hypothesis predicts higher speed, resulting from active spine motion. Here we present results from hardware experiments with an active-spine equipped quadruped bounding robot, showing that through reduction of horizontal impulse the robot's mechanical cost of transport was reduced.
We studied the effect of the control of an active spine versus a fixed spine, on a quadruped robo... more We studied the effect of the control of an active spine versus a fixed spine, on a quadruped robot running in bound gait. Active spine supported actuation led to faster locomotion, with less foot sliding on the ground, and a higher stability to go straight forward. However, we did no observe an improvement of cost of transport of the spine-actuated, faster robot system compared to the rigid spine.
ABSTRACT We compare the effects of linear and piecewise linear compliant spines on locomotion per... more ABSTRACT We compare the effects of linear and piecewise linear compliant spines on locomotion performance of quadruped robots in terms of energy efficiency and locomotion speed through a set of simulations and experiments. We first present a simple locomotion system that behaviorally resembles a bounding quadruped with flexible spine. Then, we show that robots with linear compliant spines have higher locomotion speed and lower cost of transportation in comparison with those with rigid spine. However, in linear case, optimal speed and minimum cost of transportation are attained at very different spine compliance values. Moreover, it is verified that fast and energy efficient locomotion can be achieved together when the spine flexibility is piecewise linear. Furthermore, it is shown that the robot with piecewise linear spine is more robust against changes in the load it carries. Superiority of piecewise linear spines over linear and rigid ones is additionally confirmed by simulating a quadruped robot in Webots and experiments on a crawling two-parts robot with flexible connection.
The ability to follow one another’s gaze plays an important role in our social cognition; especi... more The ability to follow one another’s gaze plays an important role in our social cognition; especially when we synchronously perform tasks together. We investigate how gaze cues can improve performance in a simple coordination task (i.e., the mirror game), whereby two players mirror each other’s hand motions. In this game, each player is either a leader or follower. To study the effect of gaze in a systematic manner, the leader’s role is played by a robotic avatar. We contrast two conditions, in which the avatar provides or not explicit gaze cues that indicate the next location of its hand. Specifically, we investigated (a) whether participants are able to exploit these gaze cues to improve their coordination, (b) how gaze cues affect action prediction and temporal coordination, and (c) whether introducing active gaze behavior for avatars makes them more realistic and human-like (from the user point of view).
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Papers by Mahdi Khoramshahi