Despite impressive advances of humanoid robotics, the autonomous planning of whole-body loco-manipulation actions in unknown environments is still an open problem. In our previous work, we addressed two fundamental aspects related to this problem: 1) the autonomous detection of end-effector contact opportunities in unknown environments and 2) the goal-directed planning of multi-contact pose sequences, which can serve as the starting point for motion planning and control approaches of reduced complexity. Both problems suffer from the extensive amounts of possible solutions, particularly due to the complexity of humanoid robots and the multitude of available contact opportunities. In this paper, we propose a method for the planning of whole-body multi-contact tasks based on our previous work on vision-based detection of loco-manipulation affordances and whole-body multi-contact pose sequence planning. We demonstrate a combined approach for planning multi-contact pose sequences with a focus on the utilization of available end-effectors for stabilizing contacts with the environment during loco-manipulation tasks. The method is evaluated in simulation in multiple exemplary scenarios based on actual sensor data and the humanoid robot ARMAR-4.

Intuitive exoskeleton control is fundamental since it contributes to improved user acceptance and wearability comfort. This requires the detection of user's motion intention and its incorporation into the exoskeleton control system. In this work, we propose a classification system based on Hidden Markov Models (HMMs), which facilitates the online classification of multi-modal sensor data acquired from a lower-limb exoskeleton based on previously defined motion patterns. For classification of these motion patterns at each time step, we consider the most recent sensor measurements by using a sliding window approach. We collected a training data set from a total number of 10 subjects performing 13 different motions with a passive exoskeleton equipped with 7 3D-force sensors and 3 inertial measurement units (IMUs). Our evaluation includes an analysis of the time needed for correct classification (latency), a validation for a training set containing all subjects and a leave-one-out validation to assess the generalization performance of the approach. The results indicate that our approach can classify motions of subjects included in the training set with an average accuracy of 92.80% and is able to achieve a generalization performance of 84.46%. With the selected parameters an average latency of 368.97 ms is achieved.

We present a novel approach for generating sequences of whole-body poses with multi-contacts for humanoid robots, which is inspired by techniques from natural language processing. To this end, we propose a probabilistic n-gram language model learned from observation of human locomotion tasks. Human motion data is automatically segmented according to detected contacts of the body with the environment to provide support, that is, support poses, which are further subdivided with regard to whole-body configuration. These poses are subsequently used to train a language model, whose words are the poses, and whose sentences represent sequences of poses. Then, we propose a planning algorithm that, given the constraints imposed by a task, finds the sequence of transitions with the highest probability according to our language model. We have applied our approach to 140 motion capture recordings of locomotion tasks that involve using one or both hands for support. The evaluation demonstrates that our approach is able to generate complex sets of pose transitions, and shows promising results regarding its application to more complex tasks.

Large-scale human motion databases are key for research questions ranging from human motion analysis and synthesis, biomechanics of human motion, data-driven learning of motion primitives, and rehabilitation robotics to the design of humanoid robots and wearable robots such as exoskeletons. In this paper we present a large-scale database of whole-body human motion with methods and tools, which allows a unifying representation of captured human motion, and efficient search in the database, as well as the transfer of subject-specific motions to robots with different embodiments. To this end, captured subject-specific motion is normalized regarding the subject's height and weight by using a reference kinematics and dynamics model of the human body, the master motor map (MMM). In contrast with previous approaches and human motion databases, the motion data in our database consider not only the motions of the human subject but the position and motion of objects with which the subject is interacting as well. In addition to the description of the MMM reference model, we present procedures and techniques for the systematic recording, labeling, and organization of human motion capture data, object motions as well as the subject–object relations. To allow efficient search for certain motion types in the database, motion recordings are manually annotated with motion description tags organized in a tree structure. We demonstrate the transfer of human motion to humanoid robots and provide several examples of motion analysis using the database.