Fig. 10
From: Geometric conditions of a two-link-and-six muscle structure based on internal force stability
Minimality discrimination of the shapes of the potential at each desired posture (green circular markers indicates a local minimized potential at the posture. Red triangular markers indicates a non-minimized potential at the posture. Black circular markers indicates a local minimized potential, however, negative tensile forces are generated on the muscles. Black triangular markers indicates a non-minimized potential, and, negative tensile forces are generated on the muscles. \(\times\) indicates that “ Vector Closure ” is not satisfied)