Optimal trajectory formation of constrained human arm reaching movements

Abstract

Opening a door, turning a steering wheel, and rotating a coffee mill are typical examples of human movements that are constrained by the physical environment. The constraints decrease the mobility of the human arm and lead to redundancy in the distribution of actuator forces (either joint torques or muscle forces). Due to this actuator redundancy, there is an infinite number of ways to form a specific arm trajectory. However, humans form trajectories in a unique way. How do humans resolve the redundancy of the constrained motions and specify the hand trajectory? To investigate this problem, we examine human arm movements in a crank-rotation task. To explain the trajectory formation in constrained point-to-point motions, we propose a combined criterion minimizing the hand contact force change and the actuating force change over the course of movement. Our experiments show a close matching between predicted and experimental data.

Manipulability analysis of human arm movements during the operation of a variable-impedance controlled robot

“…Most of these studies, however, deal with free movements, although human movements in daily activities are often constrained by task environments. There have been some reports on human arm movements during a crank rotation task restricted on the horizontal plane [2], [3], which is an example of the constrained tasks, but they do not take into account of the influence of environmental constraints, such as dynamic properties and a operational trajectory determined by the constrained mechanism, on human arm movements and operational feeling.…”

A theoretical analysis of the influence of wheelchair seat position on upper extremity demand

“…A simulated annealing optimization algorithm (Goffe et al, 1994) was used to find the optimal muscle excitation parameters that simulated wheelchair propulsion and minimized the change in hand force and torques (Ohta et al, 2004), with the cost function defined as:…”

“…Therefore, the cost function that minimized the change in hand force and torques used to generate the simulations may not be the one used by the nervous system during wheelchair propulsion. However, similar dynamic cost functions (minimizing change in torque and/or hand force) have frequently been used to successfully reproduce upper extremity movements (e.g., Uno et al, 1989;Nakano et al, 1999;Ohta et al, 2004;Svinin et al, 2005). In addition, the cost function used ensured a smooth, stable motion in both the joint and handrim coordinate frames while limiting co-contraction similarly to functions that are based on reduction of muscle activations, forces or stresses.…”

Genesis of booster curves in Electric Power Assistance Steering systems

“…They can be divided in two main classes: dynamic and kinematic criteria. Dynamic optimization criteria aim to minimize quantities like the energy or the power ( [12], [13]), the torque and the torque change [14] exerted during a movement. The most common kinematic criterion is based on the minimization of the jerk [29].…”

“…For example, to optimize the muscular effort during a one degree-of-freedom repetitive exercise motion, authors in ( [12], [13]) choose to maximize the power spent by the user. To explain the trajectory formation in a constrained point-to-point motion, in [14] authors propose a combined criterion minimizing the variation of the hand contact force and the change of the actuating force over the course of the movement. In the case of a planar horizontal movements with one mechanical degree of freedom [15], the authors find an analytical expression for the predicted minimum torque change trajectories.…”