In this paper we present the humanoid robot
LOLA, its mechatronic hardware design, simulation and real-time walking control. The goal of the
LOLA-project is to build a machine capable of stable, ...autonomous, fast and human-like walking.
LOLA is characterized by a redundant kinematic configuration with 7-DoF legs, an extremely lightweight design, joint actuators with brushless motors and an electronics architecture using decentralized joint control. Special emphasis was put on an improved mass distribution of the legs to achieve good dynamic performance. Trajectory generation and control aim at faster, more flexible and robust walking. Center of mass trajectories are calculated in real-time from footstep locations using quadratic programming and spline collocation methods. Stabilizing control uses hybrid position/force control in task space with an inner joint position control loop. Inertial stabilization is achieved by modifying the contact force trajectories.
The stress-activated protein kinase JNK plays an important role in the stability and activities of key regulatory proteins, including c-Jun, ATF2, and p53. To better understand mechanisms underlying ...the regulation of JNK activities, we studied the effect of expression of the amino-terminal JNK fragment (N-JNK; amino acids 1–206) on the stability and activities of JNK substrates under nonstressed growth conditions, as well as after exposure to hydrogen peroxide. Mouse fibroblasts that express N-JNK under tetracycline-off (tet-off) inducible promoter exhibited elevated expression of c-Jun, ATF2, and p53 upon tetracycline removal. This increased coincided with elevated transcriptional activities of p53, but not of c-Jun or ATF2, as reflected in luciferase activities ofp21Waf1/Cip1 -Luc, AP1-Luc, andJun2-Luc, respectively. Expression of N-JNK in cells that were treated with H2O2 impaired transcriptional output as reflected in a delayed and lower level of c-Jun-, limited ATF2-, and reduced p53-transcriptional activities. N-JNK elicited an increase in H2O2-induced cell death, which is p53-dependent, because it was not seen in p53 null cells yet could be observed upon coexpression of p53 and N-JNK. The ability to alter the activity of ATF2, c-Jun, and p53 and the degree of stress-induced cell death by a JNK-derived fragment identifies new means to elucidate the nature of JNK regulation and to alter the cellular response to stress.
This paper presents the 25-DOF full-size humanoid robot LOLA . Our goal is to realize fast and human-like walking. Furthermore, we want to increase the robot's autonomous, vision-guided walking ...capabilities. LOLA is characterized by a redundant kinematic configuration, an extremely lightweight design, joint actuators with brushless motors and an electronics architecture using decentralized joint control. Special emphasis was put on an improved mass distribution to achieve good dynamic performance. Center of mass trajectories are calculated in real-time from footstep locations using a spline collocation method. Reference trajectories are modified by a stabilizing control system based on hybrid force/position control with an inner joint position control loop.
Bipedal locomotion is more than dynamically stable walking. The redundant kinematic design of humanoid robots allows for complex motions in complex scenarios. One challenge of current robotic ...research is the exploitation of the capacities of redundant robots in real-time applications. In this paper, we present and evaluate methods for real-time motion generation of redundant robots. The proposed methods are based on a model-predictive approach. We propose and compare methods for optimization of robot motions defined by parameterized task-space trajectories and for redundancy resolution. The approaches are successfully combined in a novel algorithm. The methods are introduced with the help of a minimal model. It shows their applicability for a wide range of complex robotic systems. We apply and validate their effectiveness and their real-time character in several experiments with different environments with the humanoid robot
Lola
.
Autonomous navigation in dynamic and unknown environments requires real-time path planning. Solving the path planning problem for bipedal locomotion quickly and robustly is one of the main challenges ...in making humanoid robots competitive against mobile platforms. In this letter, we propose strategies to use mobile platform planners for improving the navigation of bipedal robots. These strategies combine advantageously continuous two-dimensional (2-D) paths with conventional step planners for humanoid robots. We introduce a mobile platform planner suitable for real-time navigation. It searches for multiple 2-D paths that makes the path planning more robust against limited calculation time and changing scenarios. It is combined with a step planner and integrated in the framework for autonomous navigation of our robot Lola. We evaluate different strategies in simulation and validate them in experiments in unknown dynamic environments.
State estimation for biped robots using multibody dynamics Wittmann, Robert; Hildebrandt, Arne-Christoph; Wahrmann, Daniel ...
2015 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS),
09/2015
Conference Proceeding
This paper introduces a new state estimator for biped robots fusing encoder, inertial and force torque measurements. The estimator is implemented as a Kalman filter that uses the dynamical model of ...the linear inverted pendulum with the center of mass (CoM) state as output. In order to compensate for disturbances and model errors we extend the model by a state for the external force and an additional input which is calculated from the dynamics error in pattern generation. Several simulation results underline the effectiveness of the proposed filter and show its robustness against disturbances. Experimental results and an application example validate the method under real world conditions.
In this review article, we describe some of the studies that have been performed using the surface-enhanced laser desorption ionization (SELDI) time-of-flight mass spectrometry and ProteinChip
® ...technology over the past few years, and highlight both their findings as well as limitations. Proteomic applications, such as target or marker identification and target validation or toxicology, will be addressed. We will also provide an examination of SELDI technology and go into the question of where possible future research may lead us.
In this paper we present a step-planner embedded in a framework which enables a humanoid robot to navigate among obstacles, exploiting its overall capacities. The system allows the robot to react to ...changes of user input or changes in a dynamic environment in real-time while walking at reasonable speeds. The proposed method relies neither on external sensors nor on color coding or textured surfaces. The key idea is to use a fast collision model based on swept-sphere-volumes (SSVs) for real-time generation of collision-free footsteps and whole-body trajectories. Using a SSV-based 3D approximation in all control modules enables the robot to avoid collisions with itself and the environment. Obstacles are detected with an on-board RGB-D sensor while the robot navigates through an environment which is not known in advance. A step-planner reacts to high-level user commands like desired velocity and direction or changes in the environment within less than a step. Instead of investigating only the footholds an articulated 3D approximation of the lower leg and the foot is considered to find feasible and optimal footstep locations. Additionally, it provides an initial solution for the swing-foot movement. Finally, collision-free swing-foot trajectories are created in real-time in the feedback control layer using all the foot's degrees of freedom. We validated this approach in experiments with our robot Lola.
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