Neural muscular delays in Equilibrium Point model of human arm trajectory

The aim of this paper is to investigate the human arm´s sensory-motor control mechanism in the trajectory planning of arm movement in the transverse plane. According to the equilibrium point hypothesis, the equilibrium configuration of joint angles and muscle torques are defined as a single variable called the equilibrium point (EP). Further, control systems reset the EP by shifting the invariant characteristic (IC) which initiates muscle activation and movement. The duration and sequences of shifting, however, are unclear. This work utilizes the spike triggering averaging (STA) technique integrated with simultaneous EMG and joint positions to find the sequences, but the nature of EMG signal does not favor the STA. The raw EMG signals were used to project sequences and time delay for the model of simulation. Our results exhibit an improvement in trajectory accuracy with decreased time delay.