We present experimental results using a passive whole-body control approach for quadruped robots that achieves dynamic locomotion while compliantly balancing the robot's trunk. We formulate the ...motion tracking as a quadratic program that takes into account the full robot rigid body dynamics, the actuation limits, the joint limits, and the contact interaction. We analyze the controller's robustness against inaccurate friction coefficient estimates and unstable footholds, as well as its capability to redistribute the load as a consequence of enforcing actuation limits. Additionally, we present practical implementation details gained from the experience with the real platform. Extensive experimental trials on the 90 kg hydraulically actuated quadruped robot validate the capabilities of this controller under various terrain conditions and gaits. The proposed approach is superior for accurate execution of highly dynamic motions with respect to the current state of the art.
In robotics, the ability of quadruped robots to perform tasks in industrial, mining, and disaster environments has already been demonstrated. To ensure the safe execution of tasks by the robot, ...meticulous planning of its foot placements and precise leg control are crucial. Traditional motion planning and control methods for quadruped robots often rely on complex models of both the robot itself and its surrounding environment. Establishing these models can be challenging due to their nonlinear nature, often entailing significant computational resources. However, a more simplified approach exists that focuses on the kinematic model of the robot’s floating base for motion planning. This streamlined method is easier to implement but also adaptable to simpler hardware configurations. Moreover, integrating impedance control into the leg movements proves advantageous, particularly when traversing uneven terrain. This article presents a novel approach in which a quadruped robot employs impedance control for each leg. It utilizes sixth-degree Bézier curves to generate reference trajectories derived from leg velocities within a planar kinematic model for body control. This scheme effectively guides the robot along predefined paths. The proposed control strategy is implemented using the Robot Operating System (ROS) and is validated through simulations and physical experiments on the Go1 robot. The results of these tests demonstrate the effectiveness of the control strategy, enabling the robot to track reference trajectories while showing stable walking and trotting gaits.
This paper details the implementation of state-of-the-art whole-body control algorithms on the humanoid robot iCub. We regulate the forces between the robot and its surrounding environment to ...stabilize a desired posture. We assume that the forces and torques are exerted on rigid contacts. The validity of this assumption is guaranteed by constraining the contact forces and torques, e.g., the contact forces must belong to the associated friction cones. The implementation of this control strategy requires the estimation of both joint torques and external forces acting on the robot. We then detail algorithms to obtain these estimates when using a robot with an iCub-like sensor set, i.e., distributed six-axis force-torque sensors and whole-body tactile sensors. A general theory for identifying the robot inertial parameters is also presented. From an actuation standpoint, we show how to implement a joint-torque control in the case of DC brushless motors. In addition, the coupling mechanism of the iCub torso is investigated. The soundness of the entire control architecture is validated in a real scenario involving the robot iCub balancing and making contact with both arms.
This paper presents the design and control of a high-speed running bipedal robot, BRAVER. The robot, which weighs 8.6 kg and is 0.36 m tall, has six active degrees, all of which are driven by custom ...back-driveable modular actuators, which enable high-bandwidth force control and proprioceptive torque feedback. We present the details of the hardware design, including the actuator, leg, foot, and onboard control systems, as well as the locomotion controller design for high dynamic tasks and improving robustness. We have demonstrated the performance of BRAVER using a series of experiments, including multi-terrains walking, up and down 15
∘
slopes, pushing recovery, and running. The maximum running speed of BRAVER reaches 1.75 m/s.
Regardless of recent advances, humanoid robots still face significant difficulties in performing locomotion tasks. Among the key challenges that must be addressed to achieve robust bipedal locomotion ...are dynamically consistent motion planning, feedback control, and state estimation of such complex systems. In this paper, we investigate the use of an external motion capture system to provide state feedback to an online whole-body controller. We present experimental results with the humanoid robot RH5 performing two different whole-body motions: squatting with both feet in contact with the ground and balancing on one leg. We compare the execution of these motions using state feedback from (i) an external motion tracking system and (ii) an internal state estimator based on inertial measurement unit (IMU), forward kinematics, and contact sensing. It is shown that state-of-the-art motion capture systems can be successfully used in the high-frequency feedback control loop of humanoid robots, providing an alternative in cases where state estimation is not reliable.
Objective:
Preservation of patient’s medical information in health care industries under Medical Sensor Networks (MSN).
Methods:
This paper proposes a novel key management technique known as k- ...secure with FBKM, which generates a robust key to allow communication between sensors present in the Body Sensor Units (BSU) and Body Central Unit (BCU). This proposed work strengthens the FBKM technique which is placed between BCU and the point accessible to medical experts at a remote place in the overall health care monitoring environment.
Results:
The FBKM technique has proved its success in authentication and security by improving genuine acceptance rate, false rejection rate, and declining false acceptance rate.
Conclusion:
The k- secure with FBKM scheme enhances the performance of the existing FBKM scheme in Medical Sensor Networks.
A Study on the conceptual structure of judo's kakehiki ARIYAMA, Atsutoshi; YAMAMOTO, Koji; HOSYO, Takashi ...
Taiikugaku kenkyu (Japan Journal of Physical Education, Health and Sport Sciences),
2023, 2023-00-00, Volume:
68
Journal Article
Open access
This study aimed to clarify the conceptual structure of the kakehiki movements in judo (offense and defense involving tactical intent leading up to a technique designed to create an advantageous ...situation) through the construction of a movement measurement scale. Until now, beginners have rarely been taught the kakehiki movements that are necessary to master the offensive and defensive movements typical of judo. This is because the kakehiki movements have been sidelined to tips and instincts of the best competitors, and no effort has been made to conceptualize them as formal knowledge that can be shared and understood by everyone. This study involved a 3-stage survey of judo competitors. The results revealed that kakehiki comprises 4 types of movement: kumite (movements for advantageous judo grips), hyoshi (movements related to rhythm and timing), ma-ai (movements related to psychological distance), and kehai offense and defense (movements to explore the other party's condition). This made it possible to structure the offensive and defensive movements of judo as a general-purpose learning program applicable to beginners as well, which has previously been relegated to tips and instincts of skilled players. By utilizing this scale, it was possible to grasp the abstract aspects of learning, such as judo offense and defense, as a comparable numerical value.
Humanoid service robots in domestic environments have to interact with humans and their surroundings in a safe and reliable way. One way to manage that is to equip the robotic systems with ...force-torque sensors to realize a physically compliant whole-body behavior via impedance control. To provide mobility, such robots often have wheeled platforms. The main advantage is that no balancing effort has to be made compared to legged humanoids. However, the nonholonomy of most wheeled systems prohibits the direct implementation of impedance control due to kinematic rolling constraints that must be taken into account in modeling and control. In this paper we design a whole-body impedance controller for such a robot, which employs an admittance interface to the kinematically controlled mobile platform. The upper body impedance control law, the platform admittance interface, and the compensation of dynamic couplings between both subsystems yield a passive closed loop. The convergence of the state to an invariant set is shown. To prove asymptotic stability in the case of redundancy, priority-based approaches can be employed. In principle, the presented approach is the extension of the well-known and established impedance controller to mobile robots. Experimental validations are performed on the humanoid robot Rollin’ Justin. The method is suitable for compliant manipulation tasks with low-dimensional planning in the task space.
We propose a locomotion framework for bipedal robots consisting of a new motion planning method, dubbed trajectory optimization for walking robots plus (TOWR+), and a new whole-body control method, ...dubbed implicit hierarchical whole-body controller (IHWBC). For versatility, we consider the use of a composite rigid body (CRB) model to optimize the robot’s walking behavior. The proposed CRB model considers the floating base dynamics while accounting for the effects of the heavy distal mass of humanoids using a pre-trained centroidal inertia network. TOWR+ leverages the phase-based parameterization of its precursor, TOWR, and optimizes for base and end-effectors motions, feet contact wrenches, as well as contact timing and locations without the need to solve a complementary problem or integer program. The use of IHWBC enforces unilateral contact constraints (i.e., non-slip and non-penetration constraints) and a task hierarchy through the cost function, relaxing contact constraints and providing an implicit hierarchy between tasks. This controller provides additional flexibility and smooth task and contact transitions as applied to our 10 degree-of-freedom, line-feet biped robot DRACO. In addition, we introduce a new open-source and light-weight software architecture, dubbed planning and control (PnC), that implements and combines TOWR+ and IHWBC. PnC provides modularity, versatility, and scalability so that the provided modules can be interchanged with other motion planners and whole-body controllers and tested in an end-to-end manner. In the experimental section, we first analyze the performance of TOWR+ using various bipeds. We then demonstrate balancing behaviors on the DRACO hardware using the proposed IHWBC method. Finally, we integrate TOWR+ and IHWBC and demonstrate step-and-stop behaviors on the DRACO hardware.
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