A motion assistance apparatus comprising: a proximal support configured to support a waist or pelvis of a user; a distal support configured to support a foot of the user, the distal support comprising a first portion and a second portion ; a support assembly configured to connect the proximal support and the distal support, and configured to adjust a rotation angle of the distal support; the support assembly comprising: a first spring (S1) configured to connect the proximal support and the first portion of the distal support; and a second spring (S2) configured to connect the proximal support and the second portion of the distal support, wherein the first spring is a first virtual spring (S1) virtually connecting the proximal support to the first portion of the distal support ; the seond spring is a second virtual spring (S2) virtually connecting the proximal support to the second portion of the distal support ; it further comprises a controller configured to control the support assembly based on a virtual dual spring-mass model designed using the proximal support as a body of mass, the virtual dual spring-mass model comprising the first virtual spring (S1) and the second virtual spring (S2); in the virtual model, only the first virtual spring (S1) and the second virtual spring (S2) of said support assembly define a separation distance between the proximal support and the distal support; and wherein at least two joints (J1, J2, J3) are arranged between the waist or pelvis and the foot of the user. a proximal support configured to support a waist or pelvis of a user; a distal support configured to support a foot of the user, the distal support comprising a first portion and a second portion ; a support assembly configured to connect the proximal support and the distal support, and configured to adjust a rotation angle of the distal support; the support assembly comprising: a first spring (S1) configured to connect the proximal support and the first portion of the distal support; and a second spring (S2) configured to connect the proximal support and the second portion of the distal support, wherein a first spring (S1) configured to connect the proximal support and the first portion of the distal support; and a second spring (S2) configured to connect the proximal support and the second portion of the distal support, wherein the first spring is a first virtual spring (S1) virtually connecting the proximal support to the first portion of the distal support ; the seond spring is a second virtual spring (S2) virtually connecting the proximal support to the second portion of the distal support ; it further comprises a controller configured to control the support assembly based on a virtual dual spring-mass model designed using the proximal support as a body of mass, the virtual dual spring-mass model comprising the first virtual spring (S1) and the second virtual spring (S2); in the virtual model, only the first virtual spring (S1) and the second virtual spring (S2) of said support assembly define a separation distance between the proximal support and the distal support; and wherein at least two joints (J1, J2, J3) are arranged between the waist or pelvis and the foot of the user. <EOS>