EXAMINATION OF THE LAMBDA-EQUILIBRIUM-POINT HYPOTHESIS WHEN APPLIED TO SINGLE DEGREE-OF-FREEDOM MOVEMENTS PERFORMED WITH DIFFERENT INERTIALLOADS

One of the theories of human motor control is the lambda Equilibrium P oint Hypothesis. It is an attractive theory since it offers an easy co ntrol scheme where the planned trajectory shifts monotionically from a n initial to a final equilibrium state. The feasibility of this model was tested by reconstructing the virtual trajectory and the stiffness profiles for movements performed with different inertial loads and exa mining them. Three types of movements were tested: passive movements, targeted movements, and repetitive movements. Each of the movements wa s performed with five different inertial loads. Plausible virtual traj ectories and stiffness profiles were reconstructed based on the lambda Equilibrium Point Hypothesis for the three different types of movemen ts performed with different inertial loads. However, the simple contro l strategy supported by the model, where the planned trajectory shifts monotonically from an initial to a final equilibrium state, could not be supported for targeted movements performed with added inertial loa d. To test the feasibility of the model further we must examine the pr obability that the human motor control system would choose a trajector y more complicated than the actual trajectory to control.