Empirical Modifications to a Phase Space Planner Which Compensates for Low Stiffness Actuation in a Planar, Point-Foot, Biped Robot

2014 ◽  
Author(s):  
Donghyun Kim ◽  
Ye Zhao ◽  
Gray Thomas ◽  
Luis Sentis
Keyword(s):  
Phase Space ◽  
Ad Hoc ◽  
Biped Robot ◽  
Open Loop ◽  
Linkage Mechanism ◽  
Space Planning ◽  
Planar Point ◽  
Flat Surfaces ◽  
Low Stiffness ◽  
Leg Movements

This paper presents an extensive experimental study of the first steps of the Hume robot. Hume is an adult sized, 20 kg, series-elastic, point-foot biped robot capable of very fast leg movements. In this study, Hume is constrained to planar motion by a linkage mechanism. We present our application of phase space planning to one, two, and three step walking, the last one over an obstacle. In the implementation, we modified the original theory and added ad-hoc adjustments since the robot could not follow the original theory’s planned walking trajectories despite their theoretical stability. We present a good correlation between the phase space plans and our various experiments, and an analysis of the robot’s final behavior. Overall the planner and ad-hoc modifications allowed us to execute very smooth gaits even over non-flat surfaces but at the same time demonstrated the shortcomings of open loop techniques.

Designing and Kinematics Analysis on Running Mechanism of Biped Robot for Water-Running

2011 ◽  
Vol 130-134 ◽  
pp. 217-221 ◽  
Author(s):  
Lin Sen Xu ◽  
Jiang Hai Zhao ◽  
Bing Li ◽  
Feng Xu
Keyword(s):  
Biped Robot ◽  
Kinematics Analysis ◽  
Linkage Mechanism ◽  
Hybrid Drive ◽  
Link Mechanism ◽  
Basilisk Lizard

A mechanism based on a Grashof crank-link mechanism and a hybrid-drive six-linkage mechanism is designed to fit its ankle and sole trajectories and imitate the function of the basilisk lizard running on water. The linkage mechanism kinematics theory and the geometric identity condition are used to analyze the mechanism kinematics, and an instance simulation is carried out to prove that the mechanism can satisfy the kinematics requirements of water-running.

scholarly journals Dynamics and stability of running on rough terrains

2019 ◽  
Vol 6 (3) ◽  
pp. 181729 ◽  
Author(s):  
Nihav Dhawale ◽  
Shreyas Mandre ◽  
Madhusudhan Venkadesan
Keyword(s):  
Sensory Feedback ◽  
Dimensionless Parameter ◽  
Sagittal Plane ◽  
Sensory Information ◽  
Open Loop ◽  
Rough Terrain ◽  
Two Dimensional ◽  
Flat Surfaces ◽  
And Control ◽  
Flat Ground

Stability of running on rough terrain depends on the propagation of perturbations due to the ground. We consider stability within the sagittal plane and model the dynamics of running as a two-dimensional body with alternating aerial and stance phases. Stance is modelled as a passive, impulsive collision followed by an active, impulsive push-off that compensates for collisional losses. Such a runner has infinitely many strategies to maintain periodic gaits on flat ground. However, these strategies differ in how perturbations due to terrain unevenness are propagated. Instabilities manifest as tumbling (orientational instability) or failing to maintain a steady speed (translational instability). We find that open-loop strategies that avoid sensory feedback are sufficient to maintain stability on step-like terrains with piecewise flat surfaces that randomly vary in height. However, these open-loop runners lose orientational stability on rough terrains whose slope also varies randomly. The orientational instability is significantly mitigated by minimizing the tangential collision, which typically requires sensory information and anticipatory strategies such as leg retraction. By analysing the propagation of perturbations, we derive a single dimensionless parameter that governs stability. This parameter provides guidelines for the design and control of both biological and robotic runners.

Optimization Synthesis on Water Running Mechanism of Biped Robot

2011 ◽  
Vol 211-212 ◽  
pp. 454-459 ◽  
Author(s):  
Lin Sen Xu ◽  
Bing Li ◽  
Feng Xu ◽  
Jiang Hai Zhao ◽  
Bao Lin Feng
Keyword(s):  
Stability Analysis ◽  
Biped Robot ◽  
Maximum Force ◽  
Critical Conditions ◽  
Kinematics Analysis ◽  
Linkage Mechanism ◽  
Hybrid Drive ◽  
Basilisk Lizard ◽  
The Stability

A mechanism based on a four-linkage mechanism and a hybrid-drive six-linkage mechanism is designed to imitate the function of the basilisk lizard running on water. The kinematics analysis of the water running mechanism is carried out by using the linkage mechanism kinematics and the D-H method. Then the stability analysis of the mechanism is carried out according to the critical conditions. At last the mechanism is simulated and optimized for getting the maximum momentum in the slap phase and the maximum force in the stroke phase. And the simulation result shows that the mechanism can satisfy the requirement of biped water running.

OPCL MIGRATION CONTROLS BETWEEN FIVE ATTRACTORS OF THE CHUA SYSTEM

1995 ◽  
Vol 05 (04) ◽  
pp. 1255-1260 ◽  
Author(s):  
E. ATLEE JACKSON
Keyword(s):  
Phase Space ◽  
Dynamic Systems ◽  
Physical System ◽  
Control Method ◽  
Resonance Method ◽  
Basins Of Attraction ◽  
Open Loop ◽  
Limited Time ◽  
Migration Control ◽  
Data Points

Jackson and Grosu [1995a] have recently proved that a new OPCL control method, involving both closed and open loop components, always has a basin of entrainment to any smooth goal dynamics, g(t) ⊂ Rn, for any dynamic system (Lipschitz flow), dx/dt = F (x, t), x ⊂ Rn. Moreover, they showed that the basins of entrainment can be made the entire phase space ("global") for many standard dynamic systems, and in particular for the Chua system [Chua et al., 1986]. In contrast to entrainment, it has been pointed out [Jackson, 1990] that migration controls, which act only for limited time and produce transfers between attractors of a multiple-attractor system, can be of great importance. The Chua system can possess five attractors, and the present study shows how it is possible to reliably produce migrations between any of these attractors using only five experimentally-obtained data points in the phase space. This migration control does not require any knowledge about the basins of attraction, nor the state of the system when the control is initiated. Moreover, the OPCL method can be used to obtain refined models of the physical system, by applying the general resonance method proposed previously [Chang et al., 1991].

Model Based Development of a 3D Printed Biped Robot

2014 ◽  
Author(s):  
Won Young Kim ◽  
Kishore Pochiraju
Keyword(s):  
3D Printing ◽  
Position Control ◽  
Biped Robot ◽  
Open Loop ◽  
Printing Technology ◽  
3D Printing Technology ◽  
Model Based ◽  
3D Printed ◽  
Link Flexibility ◽  
Printing Techniques

As 3D printing technology becomes more ubiquitous and pervasive, printed robot structures are likely to become popular. However, these 3D printed structures have inherent flexibility which causes link deflections and vibrations that lead to difficulties in maintaining gait and produce instabilities during motion. In this paper a biped robot, realized with 3D printing techniques, was modeled and its gait was simulated under position control. Spring and damper elements are used within powered joints to model the link flexibility. Servos were placed at the joints and an open-loop gait trajectory was executed by posing the robot through a series of servo angles. The gait of the printed robot was designed using the model. The printed robot’s stability and accelerations during the motion were characterized with 3-axis accelerometers and gyroscopes mounted on the robot. The acceleration measurements from the printed robot are then compared with the model behavior.

scholarly journals A Wearable Closed-Loop Insulin Delivery System Based on Low-Power SoCs

Electronics ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 612 ◽  
Author(s):  
Jesús Berián ◽  
Ignacio Bravo ◽  
Alfredo Gardel ◽  
José Luis Lázaro ◽  
Sergio Hernández
Keyword(s):  
Embedded System ◽  
Closed Loop ◽  
Ad Hoc ◽  
Glucose Sensor ◽  
Insulin Pump ◽  
Insulin Delivery ◽  
Open Loop ◽  
Number Of Patients ◽  
Do It Yourself ◽  
Conventional Manner

The number of patients living with diabetes has increased significantly in recent years due to several factors. Many of these patients are choosing to use insulin pumps for their treatment, artificial systems that administer their insulin and consist of a glucometer and an automatic insulin supply working in an open loop. Currently, only a few closed-loop insulin delivery devices are commercially available. The most widespread systems among patients are what have been called the “Do-It-Yourself Hybrid Closed-Loop systems.” These systems require the use of platforms with high computing power. In this paper, we will present a novel wearable system for insulin delivery that reduces the energy and computing consumption of the platform without affecting the computation requirements. Patients’ information is obtained from a commercial continuous glucose sensor and a commercial insulin pump operating in a conventional manner. An ad-hoc embedded system will connect with the pump and the sensor to collect the glucose data and process it. That connection is accomplished through a radiofrequency channel that provides a suitable system for the patient. Thus, this system does not require to be connected to any other processor, which increases the overall stability. Using parameters configured by the patient, the control system will make automatic adjustments in the basal insulin infusion thereby bringing the patient’s glycaemia to the target set by a doctor’s prescription. The results obtained will be satisfactory as long as the configured parameters faithfully match the specific characteristics of the patient. Results from the simulation of 30 virtual patients (10 adolescents, 10 adults, and 10 children), using a python implementation of the FDA-approved (Food and Drug Administration) UVa (University of Virginia)/Padova Simulator and a python implementation of the proposed algorithm, are presented.

scholarly journals Leg amputation modifies coordinated activation of the middle leg muscles in the cricket Gryllus bimaculatus

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Dai Owaki ◽  
Hitoshi Aonuma ◽  
Yasuhiro Sugimoto ◽  
Akio Ishiguro
Keyword(s):  
Ground Surface ◽  
Gryllus Bimaculatus ◽  
Flat Surfaces ◽  
Leg Muscles ◽  
Control Paradigm ◽  
Before And After ◽  
Tripod Gait ◽  
Leg Movement ◽  
Leg Amputation ◽  
Leg Movements

AbstractInsects alter their walking pattern in order to respond to demands of an ever-changing environment, such as varying ground surface textures. They also exhibit resilient and flexible ability to retain the capacity to walk even after substantial changes in their body properties, e.g. leg amputation. While the motor control paradigm governing the inter-leg coordination in such adaptive walking has been extensively described in past studies, the mechanism remains unknown. Here, we examined this question by using the cricket (Gryllus bimaculatus), which shows a tetrapod/tripod gait on a flat surfaces, like many other insects. We performed leg amputation experiments to investigate modifications of leg movements and coordination of muscle activities. We simultaneously recorded (1) the leg movements, locomotion velocity, and body rotation and (2) the leg movements and leg muscles activities before and after leg amputation. Crickets displayed adaptive coordination of leg movement patterns in response to amputations. The activation timings of levator muscles in both middle legs tended to synchronize in phase when both legs were amputated at the coxatrochanteral joint. This supports the hypothesis that an intrinsic contralateral connection within the mesothoracic ganglion exists, and that mechanosensory feedback from the legs override this connection, resulting in the anti-phase movement of a normal gait.

scholarly journals Open-Loop Spatial Multiplexing and Diversity Communications in Ad Hoc Networks

2011 ◽  
Vol 57 (1) ◽  
pp. 317-344 ◽  
Author(s):  
Raymond H. Y. Louie ◽  
Matthew R. McKay ◽  
Iain B. Collings
Keyword(s):  
Ad Hoc Networks ◽  
Ad Hoc ◽  
Open Loop ◽  
Spatial Multiplexing ◽  
Hoc Networks
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