Feedback gains for correcting small perturbations to standing posture

A dynamical model of the neuromusculoskeletal mechanics of a cat hind limb has been developed and used to investigate the feedback regulation of standing posture under small perturbations. The model is a three-joint limb, moving only in the sagittal plane and driven by ten musculotendon actuators each having response dynamics dependent on activation kinetics and muscle kinematics. Under small perturbations the nonlinear postural regulation mechanism is approximately linear, and sensors that could provide state feedback exist. Thus, the linear quadratic regulator is proposed as a model for the structure of the feedback controller for regulation of small perturbations. System states are chosen to correspond to the known outputs of physiological sensors: muscle forces, a combination of muscle lengths and velocities, joint angles and velocities, and motoneuron activities. Thus the feedback gain matrices computed can be related to the spinal neural circuits. It is shown that a strategy of regulating all the states leads to controllers that best mimic the externally measured behavior of real cats.<<ETX>>

[1]  C. Sherrington.  Flexion‐reflex of the limb, crossed extension‐reflex, and reflex stepping and standing , 1910, The Journal of physiology.

[2]  P. Rack,et al.  The effects of length and stimulus rate on tension in the isometric cat soleus muscle , 1969, The Journal of physiology.

[3]  G. C. Joyce,et al.  The mechanical properties of cat soleus muscle during controlled lengthening and shortening movements , 1969, The Journal of physiology.

[4]  D. Jacobson,et al.  Studies of human locomotion via optimal programming , 1971 .

[5]  G. Orlovsky.  The effect of different descending systems on flexor and extensor activity during locomotion. , 1972, Brain research.

[6]  A. Laub.  A schur method for solving algebraic Riccati equations , 1978, 1978 IEEE Conference on Decision and Control including the 17th Symposium on Adaptive Processes.

[7]  J C Houk,et al.  Regulation of stiffness by skeletomotor reflexes. , 1979, Annual review of physiology.

[8]  H. Forssberg.  Phasic gating of cutaneous reflexes during locomotion , 1981 .

[9]  E. Jankowska,et al.  Common interneurones in reflex pathways from group 1a and 1b afferents of ankle extensors in the cat. , 1981, The Journal of physiology.

[10]  P. Matthews.  Proprioceptors and the Regulation of Movement , 1981 .

[11]  J. Stein.  An introduction to neurophysiology , 1982 .

[12]  P. Matthews.  Where does Sherrington's "muscular sense" originate? Muscles, joints, corollary discharges? , 1982, Annual review of neuroscience.

[13]  C. Gans.  Fiber architecture and muscle function. , 1982, Exercise and sport sciences reviews.

[14]  Richard B. Stein,et al.  What muscle variable(s) does the nervous system control in limb movements? , 1982, Behavioral and Brain Sciences.

[15]  F. Zajac,et al.  Neuromuscular and Musculoskeletal Control Models for the Human Leg , 1983, 1983 American Control Conference.

[16]  G. Loeb.  The Control and Responses of Mammalian Muscle Spindles During Normally Executed Motor Tasks , 1984, Exercise and sport sciences reviews.

[17]  Thomas A. McMahon,et al.  Muscles, Reflexes, and Locomotion , 1984 .

[18]  Gerald E. Loeb,et al.  What the Cat’s Hindlimb Tells the Cat’s Spinal Cord , 1985 .

[19]  G E Loeb,et al.  Activity of spindle afferents from cat anterior thigh muscles. I. Identification and patterns during normal locomotion. , 1985, Journal of neurophysiology.

[20]  D. McCrea.  Spinal cord circuitry and motor reflexes. , 1986, Exercise and sport sciences reviews.

[21]  D. McCloskey,et al.  The role of joint receptors in human kinaesthesia when intramuscular receptors cannot contribute. , 1987, The Journal of physiology.

[22]  Ronald F. Zernicke,et al.  Predictions for neural control based on limb dynamics , 1987, Trends in Neurosciences.

[23]  D G Stuart,et al.  Animal solutions to problems of movement control: the role of proprioceptors. , 1988, Annual review of neuroscience.

[24]  F. Zajac.  Muscle and tendon: properties, models, scaling, and application to biomechanics and motor control. , 1989, Critical reviews in biomedical engineering.