Christian Ott - Profile on Academia.edu (original) (raw)
Papers by Christian Ott
2014 IEEE-RAS International Conference on Humanoid Robots, 2014
This paper gives an overview on the torquecontrolled humanoid robot TORO, which has evolved from ... more This paper gives an overview on the torquecontrolled humanoid robot TORO, which has evolved from the former DLR Biped. In particular, we describe its mechanical design and dimensioning, its sensors, electronics and computer hardware. Additionally, we give a short introduction to the walking and multi-contact balancing strategies used for TORO. Recently, torque control for humanoid robots has attracted increased attention. The main expected features-as compared to position control-include robust interaction with the environment and safe and compliant behavior during human robot interaction and in case of self-collisions. Amongst these, the human safety issue probably plays the most crucial role with regard to the use of humanoid robots in the human society [19], [20]. The field of torque control can
IEEE Robotics & Automation Magazine, 2016
T his article provides a theoretical and thorough experimental comparison of two distinct posture... more T his article provides a theoretical and thorough experimental comparison of two distinct posture control approaches: 1) a fully model-based control approach and 2) a biologically inspired approach derived from human observations. While the robotic approach can easily be applied to balancing in three-dimensional (3-D) and multicontact (MC) situations, the biologically inspired balancer currently only works in two-dimensional situations but shows interesting robustness properties under time delays in the feedback loop. This is an important feature when considering the signal transmission and processing properties in the human sensorimotor system. Both controllers were evaluated in a series of experiments with a torque-controlled humanoid robot (TORO). This article concludes with some suggestions for the improvement of model-based balancing approaches in robotics. A Neurorobotics Approach Neurorobotics is a relatively new interdisciplinary research field in which results from neuroscience and robotics are combined. It is inspired by the idea that the way the human brain works is interlinked with the embodiment, i.e., with the properties of the human body, by which the physical interaction with the environment is performed. In the neurorobotics approach, concepts from neuroscience are validated by robotic
Industrial Robot: An …, 2007
The paper presents a new generation of torque-controlled lightweight robots (LWR) developed at th... more The paper presents a new generation of torque-controlled lightweight robots (LWR) developed at the Institute of Robotics and Mechatronics of the German Aerospace Center. In order to act in unstructured environments and interact with humans, the robots have design features and control/software functionalities which distinguish them from classical robots, such as: load-to-weight ratio of 1:1, torque sensing in the joints, active vibration damping, sensitive collision detection, as well as compliant control on joint and Cartesian level. Due to the partially unknown properties of the environment, robustness of planning and control with respect to environmental variations is crucial. After briefly describing the main hardware features, the paper focuses on showing how joint torque sensing (as a main feature of the robot) is consequently used for achieving the above mentioned performance, safety, and robustness properties.
IFAC-PapersOnLine, 2015
In this paper a coordinate transformation is proposed that provides an inertially decoupled struc... more In this paper a coordinate transformation is proposed that provides an inertially decoupled structure for the equations of motion of a floating base robot. As the center of mass (CoM) has been used both for locomotion and balancing of legged robots because of its decoupled dynamics from the rest of the system, we expect to benefit from our coordinate transformation since it allows to separate the linear and angular centroidal dynamics from the joint dynamics. Gaining insights about the model, simpler and more effective control laws can be developed. As an example of application, the proposed transformation is used in the derivation of a humanoid balance controller.
Steps Towards Energy Efficiency in Elastically Actuated Robots
Proceedings of the 19th International Conference on CLAWAR 2016, 2016
This paper provides a theoretical and thorough experimental comparison of two distinct posture co... more This paper provides a theoretical and thorough experimental comparison of two distinct posture control approaches: a fully model-based control approach, and a biologically-inspired approach derived from human observations. While the robotic approach can easily be applied to balancing in 3D and multi-contact situations, the biologically inspired balancer works currently only in 2D but shows interesting robustness properties under time delays in the feedback loop. This is an important feature when considering the signal transmission and processing properties in the human sensorimotor system. Both controllers were evaluated in a series of experiments with a torque controlled humanoid robot. The paper concludes with some suggestions for the improvement of model-based balancing approaches in robotics.
We address the problem of generating and stabilising a periodic walking pattern for a biped robot... more We address the problem of generating and stabilising a periodic walking pattern for a biped robot. A novel control framework based on adaptive oscillators combined with dynamic movement primitives was proposed. The proposed control system is a multi step process, where in the first step the system learns the dynamic walking trajectory which is demonstrated by imitating a spring loaded inverted pendulum (SLIP) controller. The learning process is completely autonomous and it is done in real time. In the second step the periodic dynamic pattern is executed using a low gain feedback controller combined with feed forward torque/force control signals. This allows compliant behaviour, smooth interaction with unstructured environment and generates stable ”open-loop” walking pattern. Compared with the SLIP walking control the proposed approach is more robust since it can produce stable walking pattern on a wider interval of forward walking velocity. The proposed control also allows smooth mo...
2014 IEEE-RAS International Conference on Humanoid Robots, 2014
This paper gives an overview on the torquecontrolled humanoid robot TORO, which has evolved from ... more This paper gives an overview on the torquecontrolled humanoid robot TORO, which has evolved from the former DLR Biped. In particular, we describe its mechanical design and dimensioning, its sensors, electronics and computer hardware. Additionally, we give a short introduction to the walking and multi-contact balancing strategies used for TORO. Recently, torque control for humanoid robots has attracted increased attention. The main expected features-as compared to position control-include robust interaction with the environment and safe and compliant behavior during human robot interaction and in case of self-collisions. Amongst these, the human safety issue probably plays the most crucial role with regard to the use of humanoid robots in the human society [19], [20]. The field of torque control can
IEEE Robotics & Automation Magazine, 2016
T his article provides a theoretical and thorough experimental comparison of two distinct posture... more T his article provides a theoretical and thorough experimental comparison of two distinct posture control approaches: 1) a fully model-based control approach and 2) a biologically inspired approach derived from human observations. While the robotic approach can easily be applied to balancing in three-dimensional (3-D) and multicontact (MC) situations, the biologically inspired balancer currently only works in two-dimensional situations but shows interesting robustness properties under time delays in the feedback loop. This is an important feature when considering the signal transmission and processing properties in the human sensorimotor system. Both controllers were evaluated in a series of experiments with a torque-controlled humanoid robot (TORO). This article concludes with some suggestions for the improvement of model-based balancing approaches in robotics. A Neurorobotics Approach Neurorobotics is a relatively new interdisciplinary research field in which results from neuroscience and robotics are combined. It is inspired by the idea that the way the human brain works is interlinked with the embodiment, i.e., with the properties of the human body, by which the physical interaction with the environment is performed. In the neurorobotics approach, concepts from neuroscience are validated by robotic
Industrial Robot: An …, 2007
The paper presents a new generation of torque-controlled lightweight robots (LWR) developed at th... more The paper presents a new generation of torque-controlled lightweight robots (LWR) developed at the Institute of Robotics and Mechatronics of the German Aerospace Center. In order to act in unstructured environments and interact with humans, the robots have design features and control/software functionalities which distinguish them from classical robots, such as: load-to-weight ratio of 1:1, torque sensing in the joints, active vibration damping, sensitive collision detection, as well as compliant control on joint and Cartesian level. Due to the partially unknown properties of the environment, robustness of planning and control with respect to environmental variations is crucial. After briefly describing the main hardware features, the paper focuses on showing how joint torque sensing (as a main feature of the robot) is consequently used for achieving the above mentioned performance, safety, and robustness properties.
IFAC-PapersOnLine, 2015
In this paper a coordinate transformation is proposed that provides an inertially decoupled struc... more In this paper a coordinate transformation is proposed that provides an inertially decoupled structure for the equations of motion of a floating base robot. As the center of mass (CoM) has been used both for locomotion and balancing of legged robots because of its decoupled dynamics from the rest of the system, we expect to benefit from our coordinate transformation since it allows to separate the linear and angular centroidal dynamics from the joint dynamics. Gaining insights about the model, simpler and more effective control laws can be developed. As an example of application, the proposed transformation is used in the derivation of a humanoid balance controller.
Steps Towards Energy Efficiency in Elastically Actuated Robots
Proceedings of the 19th International Conference on CLAWAR 2016, 2016
This paper provides a theoretical and thorough experimental comparison of two distinct posture co... more This paper provides a theoretical and thorough experimental comparison of two distinct posture control approaches: a fully model-based control approach, and a biologically-inspired approach derived from human observations. While the robotic approach can easily be applied to balancing in 3D and multi-contact situations, the biologically inspired balancer works currently only in 2D but shows interesting robustness properties under time delays in the feedback loop. This is an important feature when considering the signal transmission and processing properties in the human sensorimotor system. Both controllers were evaluated in a series of experiments with a torque controlled humanoid robot. The paper concludes with some suggestions for the improvement of model-based balancing approaches in robotics.
We address the problem of generating and stabilising a periodic walking pattern for a biped robot... more We address the problem of generating and stabilising a periodic walking pattern for a biped robot. A novel control framework based on adaptive oscillators combined with dynamic movement primitives was proposed. The proposed control system is a multi step process, where in the first step the system learns the dynamic walking trajectory which is demonstrated by imitating a spring loaded inverted pendulum (SLIP) controller. The learning process is completely autonomous and it is done in real time. In the second step the periodic dynamic pattern is executed using a low gain feedback controller combined with feed forward torque/force control signals. This allows compliant behaviour, smooth interaction with unstructured environment and generates stable ”open-loop” walking pattern. Compared with the SLIP walking control the proposed approach is more robust since it can produce stable walking pattern on a wider interval of forward walking velocity. The proposed control also allows smooth mo...