Arm supporting exoskeleton with a variable force generator

An arm supporting exoskeleton comprising an arm link mechanism, the arm link mechanism comprising:

• a proximal link;
• a distal link, configured to rotate relative to the proximal link around a first rotational axis;
• an arm coupler, attached to the distal link and configured to couple an upper arm of a person to the distal link;
• and
• a variable force generator, comprising a first spring and a second spring, configured to create a torque between the proximal link and the distal link, and is configured to generate at least a first stiffness rate and a second stiffness rate, wherein:
• when the variable force generator is in a first force mode, the variable force generator generates the first stiffness rate defined by the first spring that supports the upper arm of the person against gravity forces and,
• when the variable force generator is in second force mode, the variable force generator generates the second stiffness rate defined by the first spring and the second spring that supports the upper arm of the person against the gravity forces.