Control of a Quadruped Robot with Bionic Springy Legs in Trotting Gait

Legged robots have better performance on discontinuous terrain than that of wheeled robots. However, the dynamic trotting and balance control of a quadruped robot is still a challenging problem, especially when the robot has multi-joint legs. This paper presents a three-dimensional model of a quadruped robot which has 6 Degrees of Freedom （DOF） on torso and 5 DOF on each leg. On the basis of the Spring-Loaded Inverted Pendulum （SLIP） model, body control algorithm is discussed in the first place to figure out how legs work in 3D trotting. Then, motivated by the principle of joint function separation and introducing certain biological characteristics, two joint coordination approaches are developed to produce the trot and provide balance. The robot reaches the highest speed of 2.0 m.s-1, and keeps balance under 250 Kg.m.s-1 lateral disturbance in the simulations. The effectiveness of these approaches is also verified on a prototype robot which runs to 0.83 m.s-1 on the treadmill, The simulations and experiments show that legged robots have good biological properties, such as the ground reaction force, and spring-like leg behavior.     

Virtual Constraint Based Control of Bounding Gait of Quadruped Robots

This paper presents a control approach for bounding gait of quadruped robots by applying the concept of Virtual Constraints (VCs).A VC is a relative motion relation between two related joints imposed to the robots in terms of a specified gait,which can drive the robot to run with desired gait.To determine VCs for highly dynamic bounding gait,the limit cycle motions of the passive dynamic model of bounding gait are analyzed.The leg length and hip/shoulder angle trajectories corresponding to the limit cycles are parameterized by leg angles using 4 th-order polynomials.In order to track the calculated periodic motions,the polynomials are imposed on the robot as virtual motion constraints by a high-level state machine controller.A bounding speed feedback strategy is introduced to stabilize the robot running speed and enhance the stability.The control approach was applied to a newly designed lightweight bioinspired quadruped robot,AgiDog.The experimental results demonstrate that the robot can bound at a frequency up to 5 Hz and bound at a maximum speed of 1.2 m·s-1 in sagittal plane with a Froude number approximating to 1.     

Organization of Efferent Sympathetic Influences Related to Cardiogenic Depressor Reflexes

In acute experiments on anesthetized dogs under open chest conditions, we studied characteristics of the efferent sympathetic influences on the heart and vessels related to realization of cardiogenic depressor vagus-mediated reflexes. Catheterization of the heart cavities and parallel recording of the mass efferent spike activities in the cardiac and vertebral sympathetic nerves and of the pressure in the aortic ventricle of the heart were used. We found that reflex shifts in the spike activity in the cardiac and vertebral nerves elicited by pharmacological stimulation of the left heart (intracoronary injections of veratrine or adrenaline) and by its nidal immune impairment resulting from injection of a cytotoxic serum demonstrate similar direction (a drop in the frequency of the efferent sympathetic activity). Yet, the dynamics of such inhibitory responses to the influence of the same stimulus and their intensity in one nerve or another and those in one and the same nerve under the influence of different stimuli are considerably dissimilar. Thus, realization of vagus-mediated cardiogenic reflexes is characterized by clear heterogeneity of the efferent sympathetic control of different regions of the cardiovascular system. Such a specificity can provide differential regulation of the heart function and functions of the vascular bed related to different cardiogenic influences (both in the norm and under conditions of formation of an injury nidus in the heart).     

Biomimetic Quadruped Robot with a Spinal Joint and Optimal Spinal Motion via Reinforcement Learning

Feline animals can run quickly using spinal joints as well as the joints that make up their four legs.This paper describes the development of a quadruped robot including a spinal joint that biomimics feline animals.The developed robot platform consists of four legs with a double 4-bar linkage type and one simplified rotary joint.In addition,Q-learning,a type of machine learning,was used to find the optimal motion profile of the spinal joint.The bounding gait was implemented on the robot system using the motion profile of the spinal joint,and it was confirmed that using the spinal joint can achieve a faster Center of Mass(CoM)forward speed than not using the spinal joint.Although the motion profile obtained through Q-learning did not exactly match the spinal angle of a feline animal,which is more multiarticular than that of the developed robot,the tendency of the actual feline animal spinal motion profile,which is sinusoidal,was similar.     

Dependence of the Magnitude of Postural Reactions in Humans on the Strength of Unilateral Galvanic Anodal and Cathodal Vestibular Stimulations

In 13 healthy volunteers, we recorded stabilographic postural reactions (side inclinations of the body) to unilateral galvanic vestibular stimulation (GVS) by rectangular current pulses (4 sec long, 2, 3, 4, 5, or 6 mA). For the cathodal GVS, the dependence of the magnitude of reaction was linear within this range. The corresponding dependence for the anodal GVS was close to linear at small currents, but the increment of the magnitude became smaller with further increase in the stimulation intensity, and a plateau was formed. A significant divergence between the two curves was observed with stimulation currents 4 mA and higher. This difference can be explained considering modern concepts on the mechanism of GVS-induced effects (an increase or a decrease in the level of tonic impulsation in fibers of the vestibular nerve under the influence of polarization). Anodal GVS continues to suppress tonic activity up to the moment where all GVS-sensitive vestibular afferents stop to generate impulses; a further increase in the intensity of hyperpolarizing current is not accompanied by a decrease in the activity in the vestibular nerve and, consequently, by an increase in the magnitude of postural reactions. The tested approach can be used for qualitative estimation of the vestibular tone in humans. Neirofiziologiya/Neurophysiology, Vol. 37, No. 2, pp. 169–176, March–April, 2005.     

Optimal Control of a Mackerel-Mimicking Robot for Energy Efficient Trajectory Tracking

A robotic fish, BASEMACK1, is designed and fabricated by mimicking the shape of a live mackerel. Three DC servo-motors are serially linked together and actuated to mimic the mackerel＇s Carangiform motion. Hydrodynamic characteristics of a fish-mimetic test model are experimentally identified and utilized in order to numerically simulate fish swimming. The discrete set of kinematic and dynamic parameters are obtained by considering required horizontal and lateral forces and minimum energy consumption. Using the optimized parameter set, optimal control of the robot is studied.     

Biomimetic Design and Optimal Swing of a Hexapod Robot Leg

Biological inspiration has spawned a wealth of solutions to both mechanical design and control schemes in the efforts to develop agile legged machines. This paper presents a compliant leg mechanism for a small six-legged robot, HITCR-ll, based on abstracted anatomy from insect legs. Kinematic structure, relative proportion of leg segment lengths and actuation system were analyzed in consideration of anatomical structure as well as muscle system of insect legs and desired mobility. A spring based passive compliance mechanism inspired by musculoskeletal structures of biological systems was integrated into distal segment of the leg to soften foot impact on touchdown. In addition, an efficient locomotion planner capable of generating natural movements for the legs during swing phase was proposed. The problem of leg swing was formulated as an optimal control procedure that satisfies a series of locomotion task terms while minimizing a biologically-based objective function, which was solved by a Gauss Pseudospectral Method （GPM） based numerical technique. We applied this swing generation algorithm to both a simulation platform and a robot prototype. Results show that the proposed leg structure and swing planner are able to successfully perform effective swing movements on rugged terrains.     

Anthropomorphic Control of a Dexterous Artificial Hand via Task Dependent Temporally Synchronized Synergies

Despite the recent influx of increasingly dexterous prostheses, there remains a lack of sufficiently intuitive control methods to fully utilize this dexterity. As a solution to this problem, a control framework is proposed which allows the control of an arbitrary number of Degrees of Freedom （DOF） through a single electromyogram （EMG） control input. Initially, the joint motions of nine test subjects were recorded while grasping and catching a cylinder. Inherent differences emerged depending upon whether the cylinder was grasped or caught. These data were used to form a distinct synergy for each task, described as the families of parametric functions of time that share a mutual time vector. These two Temporally Synchronized Synergies （TSS） were derived to reflect the task dependent control strategies adopted by the initial participants. These synergies were then mapped to a dexterous artificial hand that was subsequently controlled by two subjects with transradial amputations. The EMG signals from these subjects were used to replace the time vector shared by the synergies, enabling the subjects to perform both tasks with a dexterous artificial hand using only a single EMG input. After a ten minute training period, the subjects learned to use the dexterous artificial hand to grasp and catch the cylinder with 100.0% and 65.0% average success rates, respectively.     

Control of an Escherichia coli mixed culture via affinity binding

A chemostat with population specific recycle was employed to alter the dynamics of a competitive mixed culture of Escherichia coli. Based on differential expression of a functional maltoporin, the two populations were separated by specific adhesion on starch-Sepharose. The slower growing population was the recycled to the reactor. The specific recycle was successful in maintaining the slower growing population at a high level than in comparable reactors without recycle.     

A Flexible and Ultrahigh Energy Density Capacitor via Enhancing Surface/Interface of Carbon Cloth Supported Colloids

Pseudocapacitors are now reaching the energy density limits set by the surface redox reaction of their electrode materials, requiring new cation paradigms for a fast cation Faradaic reaction with high capacitance. In this work, a flexible and ultrahigh energy density capacitor is reported via enhancing surface/interface of active colloids and supported carbon cloth. A flexible asymmetrical capacitor assembled with Ni²⁺ colloidal cathode and Fe³⁺ colloidal anode displays a high energy density of 353 W h kg^?1 at the power density of 2250 W kg^?1, outperforming recent reported pseudocapacitors, and shows superior cycling stability after 10 000 charge–discharge cycles at current density of 30 A g^?1. This work demonstrates that the optimized surface/interface of carbon cloth and colloids can lead to the enhancement of both stability and activity of colloidal electrode.     

The Impact of Energy Management Control Systems on Energy Efficiency in the German Manufacturing Industry

Although previous studies point to much (untapped) potential for energy efficiency enhancement in industry, empirical research that adapts findings of environmental control to the context of energy management remains widely neglected. Specifically, previous environmental research suggests that the implementation of energy management control systems (EnMCS) could be an effective lever for companies to enhance their production systems and operations toward energy efficiency. Yet, empirical evidence for this theoretical proposition is rather missing; thus, debate continues regarding whether the high investments to set up a comprehensive EnMCS pay off in the long run. Based on a sample of 236 German manufacturing companies, this study combines primary data that capture the configuration of EnMCS with secondary data that were used to calculate energy efficiency. The results provide evidence that the extent of EnMCS implementation positively relates to firms’ energy efficiency. Findings from additional moderation analysis suggest that companies might enhance the relationship of EnMCS and energy efficiency performance by establishing a full‐time energy manager or by using external energy consulting support.     

鹤山马占相思人工林的能量现存量及能量流动

通过测定广东鹤山一个马占相思（Ａｅａｅｉａ ｍａｎｇｉｕｎ）人工林的辐射能环境,优势种的净光合速率、呼吸速率和生产力,群落的生物量及热值,定量地刻划了太阳辐射能被马占相思群群吸收、固定、转化、损耗、积累和分配的生物能量学过程。全年抵达林冠上层的总太阳辐射能力４３５１．４ＭＪ．ｍ＾－２．ｓ＾－１,能量量为１４．８ＭＪ．ｍ＾－２．ｓ＾－１,折合光能利用效率为０．３４％,群落的能量正面量为１９３．９ＭＪ     

Energy and greenhouse gas balance of bioenergy production from poplar and willow: a review

Short‐rotation woody crops (SRWC) such as poplar and willow are an important source of renewable energy. They can be converted into electricity and/or heat using conventional or modern biomass technologies. In recent years many studies have examined the energy and greenhouse gas (GHG) balance of bioenergy production from poplar and willow using various approaches. The outcomes of these studies have, however, generated controversy among scientists, policy makers, and the society. This paper reviews 26 studies on energy and GHG balance of bioenergy production from poplar and willow published between 1990 and 2009. The data published in the reviewed literature gave energy ratios (ER) between 13 and 79 for the cradle‐to‐farm gate and between 3 and 16 for cradle‐to‐plant assessments, whereas the intensity of GHG emissions ranged from 0.6 to 10.6 g CO₂ Eq MJ_biomass^?1 and 39 to 132 g CO₂ Eq kWh^?1. These values vary substantially among the reviewed studies depending on the system boundaries and methodological assumptions. The lack of transparency hampers meaningful comparisons among studies. Although specific numerical results differ, our review revealed a general consensus on two points: SRWC yielded 14.1–85.9 times more energy than coal (ER_coal～0.9) per unit of fossil energy input, and GHG emissions were 9–161 times lower than those of coal (GHG_coal～96.8). To help to reduce the substantial variability in results, this review suggests a standardization of the assumptions about methodological issues. Likewise, the development of a widely accepted framework toward a reliable analysis of energy in bioenergy production systems is most needed.     

Analysis of reflex modulation with a biologically realistic neural network

In this study, a neuromusculoskeletal model was built to give insight into the mechanisms behind the modulation of reflexive feedback strength as experimentally identified in the human shoulder joint. The model is an integration of a biologically realistic neural network consisting of motoneurons and interneurons, modeling 12 populations of spinal neurons, and a one degree-of-freedom musculoskeletal model, including proprioceptors. The model could mimic the findings of human postural experiments, using presynaptic inhibition of the Ia afferents to modulate the feedback gains. In a pathological case, disabling one specific neural connection between the inhibitory interneurons and the motoneurons could mimic the experimental findings in complex regional pain syndrome patients. It is concluded that the model is a valuable tool to gain insight into the spinal contributions to human motor control. Applications lay in the fields of human motor control and neurological disorders, where hypotheses on motor dysfunction can be tested, like spasticity, clonus, and tremor. Action Editor: Karen Sigvardt