Dynamics and control of separable coupled rigid body systems.

This paper explores the dynamics of separable coupled rigid body systems, a special class of constrained rigid body systems. These are defined as two systems that interact with each other by forces of contact, resulting in a reduction in dimensionality and complexity. The mechanics and consequences of this reduction are investigated here.

A model of the basal ganglia in voluntary movement and postural reactions.

A basal ganglia central pattern generator (CPG) is developed and its role in voluntary movements on the ground and postural reactions on a disturbed platform are studied and analysed by simulation. Biped dynamics and platform kinematics are utilised. The effects of agonist-antagonist muscular co-activation and joint stiffness are formulated.

Central mechanisms for force and motion--towards computational synthesis of human movement.

Anatomical, physiological and experimental research on the human body can be supplemented by computational synthesis of the human body for all movement: routine daily activities, sports, dancing, and artistic and exploratory involvements. The synthesis requires thorough knowledge about all subsystems of the human body and their interactions, and allows for integration of known knowledge in working modules. It also affords confirmation and/or verification of scientific hypotheses about workings of the central nervous system (CNS).

A simple strategy for jumping straight up.

Jumping from a stationary standing position into the air is a transition from a constrained motion in contact with the ground to an unconstrained system not in contact with the ground. A simple case of the jump, as it applies to humans, robots and humanoids, is studied in this paper. The dynamics of the constrained rigid body are expanded to define a larger system that accommodates the jump.

The effect of resistance level and stability demands on recruitment patterns and internal loading of spine in dynamic flexion and extension using a simple trunk model.

The effects of external resistance on the recruitment of trunk muscles in sagittal movements and the coactivation mechanism to maintain spinal stability were investigated using a simple computational model of iso-resistive spine sagittal movements. Neural excitation of muscles was attained based on inverse dynamics approach along with a stability-based optimisation. The trunk flexion and extension movements between 60° flexion and the upright posture against various resistance levels were simulated.

Control of constraint forces and trajectories in a rich sensory and actuation environment.

A simple control strategy is proposed and applied to a class of non-linear systems that have abundant sensory and actuation channels as in living systems. The main objective is the independent control of constrained trajectories of motion, and control of the corresponding constraint forces. The peripheral controller is a proportional, derivative and integral (PID) controller.

Dynamic stability of spine using stability-based optimization and muscle spindle reflex.

A computational method for simulation of 3-D movement of the trunk under the control of 48 anatomically oriented muscle actions was developed. Neural excitation of muscles was set based on inverse dynamics approach along with the stability-based optimization. The effect of muscle spindle reflex response on the trunk movement stability was evaluated upon the application of a perturbation moment.

Quantitative analysis of the ankle strategy under translational platform disturbance.

The ankle strategy is one of the postural adjustment maneuvers humans utilize when the support platform is disturbed. This paper presents a quantitative analysis of the ankle strategy. A three-link sagittal biped model is considered.

Dynamics, stability, and control of stepping.

The dynamics, stability, and control of stepping are considered. The role of internal models is elaborated. The main objective of the paper is to provide a better understanding of the machinery and processing in the central nervous system (CNS) that relates to stepping.

Rhythmic Movement of a Pair of One-Link Arms: Coordination by Intermittent Control.

This paper considers the coordination and control of periodic movements of a pair of one-link arms. The system consists of two one-link arms each controlled by two muscle-like actuators. The muscle-like actuators are activated by simulated neural inputs.