Abstract: A hybrid electric hydraulic drive system, having a first cylinder (75) having a left chamber (32) and a right chamber (34) separated by a piston (22). A second cylinder (76) has a single or sole chamber (74) for receiving hydraulic fluid with the second cylinder enclosing a second piston (78). The second cylinder is substantially equal in length to the first cylinder and is rigidly attached to the first cylinder. A pump (14) is fluidly connected to the left chamber (32) by a first fluid passage (16) and is fluidly connected to the right chamber (34) by a second fluid passage (18). A third fluid passage (80) is directly connected to the right chamber (34) and to the sole fluid chamber (74) of the second cylinder (76). A first rod (30) is connected to the piston (22) and a second rod (84) is connected to the second piston (78). The first and second rods are connected by a connecting element so the rods move in unison.

Abstract: A locomotion simulator has two independently controlled movable footpads. Each footpad is positioned dynamically in three-dimensions. The top of each footpad has a controlled rotational motion, and the assembly having the two footpads is rotated under control. In operation, a user, whose feet are tracked in position and angle, walks or runs on the simulator and the footpads are controlled to simulate ground contact. Controlled rotation and translation movements permit simulation of turning, climbing, and decending.