Postural balance using a disturbance rejection method

Zielińska, Teresa; Gao, Zhingiang; Zurawska, Magdalena; Zheng, Qian; Mergner, Thomas; Lippi, Vittorio

doi:10.1109/romoco.2017.8003888

Cited by 5 publications

(3 citation statements)

References 13 publications

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“…Considering that robots and exoskeletons do not usually have a full body sensor input for contact forces, the identification of unexpected contacts with the environment should be performed on the basis of the available sensors exploiting the knowledge of the dynamics. This, for example, can be performed using a Luenberger observer with an extended state vector featuring the external force as an additional state variable [36] or, in order to cover more general nonlinear cases, a particle filter [37]. In the case of the DEC, the contact force is represented as an extra torque applied on a joint.…”

Section: Human-inspired Control System In Robotic Platformmentioning

confidence: 99%

A Challenge: Support of Standing Balance in Assistive Robotic Devices

Lippi

Mergner

2020

Applied Sciences

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Neurological patients using a powered lower-body exoskeleton for rehabilitation of standing and walking skills in an upright body pose face the safety challenge of postural instability and fall. Current research, therefore, develops exoskeletons with self-balancing functions. This study suggests basing the exoskeleton’s stabilization of standing posture on a human-derived postural control mechanism. A corresponding control system has previously been successfully tested with specific balancing tasks in humanoid robots. Here, we provide a short introduction into the control method and, using a lightweight robot, present as a test of the balancing an experimental shift in the body weight distribution (as if, e.g., a human exoskeleton user was raising an arm or leaning the upper body or lifting an external weight). An overview of other specific balancing tests previously already investigated in humans and humanoids is also briefly mentioned. Overall, the tests will allow the quantification of the capabilities of self-balancing exoskeletons developed for patients with partial paralysis of lower body sensorimotor functions.

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Section: Human-inspired Control System In Robotic Platformmentioning

confidence: 99%

A Challenge: Support of Standing Balance in Assistive Robotic Devices

Lippi

Mergner

2020

Applied Sciences

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“…The TFS dimensions and the system parameters are given in Table 1. System has 80% of the maximum torque of the ankle [12].…”

Section: Torsional Flat Springmentioning

confidence: 99%

Human postural ankle torque control model during standing posture with a series elastic muscle-tendon actuator

2020

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The main motivation behind the creation of a compliant actuation system is to provide safety, capability of storing energy, and improved performance levels in dynamic behavior of the mechanical human ankle. In this paper, a torsional flat spring (TFS) is proposed to provide high compliance and deformation values for human ankle series elastic muscletendon actuator system (HA-SEMTAS). The proposed torsional flat spring uses two torsional flat spiral spring in opposite directions, as the torsional flat spiral spring generates torque only in one direction. First, we present the characteristics of the TFS for an ankle joint, and the design and modeling of the HA-SEMTAS are developed. Modelling of the HA-SEMTAS simulates the responses of fluctuations in the center of mass and center of pressure and offers the possibility of measuring sensor activation, decomposition of reactive torque and participation of each set of muscle groups to balance posture. In order to control ankle angles and torque of Human system, torque controllers (PID and PD-feedforward) are generated for (HA-SEMTAS). The controller inputs are torsional flat spring position errors and error rates. Feedforward and integral action were applied to reduce the steady-state error of the system. It is seen that PID + ff of the system developed here is robust to step and ramp-type disturbances. Real-time controllers are embedded in GoogolTech GT-800 Industrial PC. Experimental results confirm that the step tracking of human upright posture behavior is satisfactory and overall system stability has improved using the proposed controller and compliant actuation system. It is also shown that PD + feedforward yields better performance than PID controller.

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“…In Alexandrov et al and Lippi et al, 1,22 the mechanism of human balance was investigated using the LIP model. Zielinska et al 45 employed a disturbance rejection controller for postural balancing taking into account the standard double pendulum model.…”

Section: Introductionmentioning

confidence: 99%

Variable Inverted Pendulum Applied to Humanoid Motion Design

Zielińska

Coba²,

2021

Robotica

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SUMMARY Double inverted pendulum model, stationary or on a cart, is computationally the simplest out of the range of reasonable models used for anthropomorphic robots motion synthesis. However, it is still not sufficient for describing more complex situations. The novel concept of variable double inverted pendulum (VDIP) for static postures and VDIP on cart (VDIPC) for dynamic cases is proposed. It provides a simplified but a sufficiently accurate tool for planning the human-like static and dynamic robot postures. Its variable parameters enable the description of both human static postures and motion dynamics. The variable length of the lower link is essential for the representation of postures attained by bending legs. The studies of a set of static and dynamic postures were used for deducing and verifying the locations of lower and upper joint of a double pendulum and the point masses. To justify the concept, human body and pendulum behaviors are compared taking into account a typical model of the human body. Static analysis was conducted by considering static human postures. Dynamic conditions were analyzed using the data acquired from human motion and thus the VDIPC definition was established. The zero moment point trajectories of the human and of VDIPC were compared, validating the correctness of VDIPC in dynamic situations. The formal description of VDIPC is provided together with the torques equilibrium condition needed for evaluating the dynamic postural stability, with the VDPIC representing the robot configuration. The VDPIC state equations are formulated in a form required by the predictive control method. The paper contributes to the motion synthesis methods of anthropomorphic robots taking into account postural control.

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Postural balance using a disturbance rejection method

Cited by 5 publications

References 13 publications

A Challenge: Support of Standing Balance in Assistive Robotic Devices

A Challenge: Support of Standing Balance in Assistive Robotic Devices

Human postural ankle torque control model during standing posture with a series elastic muscle-tendon actuator

Variable Inverted Pendulum Applied to Humanoid Motion Design

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