A powered lower extremity orthotic, configured to be coupled to first and second lower limbs of a person, comprising, for each of said first and second lower limbs, a respective first and second leg including: a shank link (105; 305) configured to be attached to a person; a thigh link (103; 307) configured to be attached to a person; a torso link configured to be attached to a person; a knee mechanism (107; 306) interconnecting said thigh link and said shank link, said knee mechanism allowing flexion and extension movements of said thigh link and said shank link relative to each other; a knee torque generator configured to generate torque between said shank link and said thigh link; a knee angle sensor creating a knee angle signal representing an angle between said shank link and said thigh link; a hip mechanism interconnecting said thigh link and said torso link, said hip mechanism allowing flexion and extension movements of said thigh link and said torso link relative to each other; a hip torque generator configured to generate torque between said shank link and said torso link; a hip angle sensor creating a hip angle signal representing an angle between said torso link and said thigh link; and a power source configured to provide electric power; a signal processor connected to the power source, the knee torque generator, the hip torque generator, the knee angle sensor and the hip angle sensor for each of said first and second legs, wherein said signal processor, for each of said first and second legs, receives signals from the knee and hip sensors, and controls the angles between said shank link and said thigh link and between said thigh link and said torso link through the knee torque and hip torque generators respectively such that a reference point on the first leg not touching a ground surface follows a predetermined trajectory that is defined by at least one Cartesian coordinate, characterized in that a position of said reference point being determined from an orientation of the second leg which is in contact with the ground surface. a shank link (105; 305) configured to be attached to a person; a thigh link (103; 307) configured to be attached to a person; a torso link configured to be attached to a person; a knee mechanism (107; 306) interconnecting said thigh link and said shank link, said knee mechanism allowing flexion and extension movements of said thigh link and said shank link relative to each other; a knee torque generator configured to generate torque between said shank link and said thigh link; a knee angle sensor creating a knee angle signal representing an angle between said shank link and said thigh link; a hip mechanism interconnecting said thigh link and said torso link, said hip mechanism allowing flexion and extension movements of said thigh link and said torso link relative to each other; a hip torque generator configured to generate torque between said shank link and said torso link; a hip angle sensor creating a hip angle signal representing an angle between said torso link and said thigh link; and a power source configured to provide electric power; a signal processor connected to the power source, the knee torque generator, the hip torque generator, the knee angle sensor and the hip angle sensor for each of said first and second legs, wherein said signal processor, for each of said first and second legs, receives signals from the knee and hip sensors, and controls the angles between said shank link and said thigh link and between said thigh link and said torso link through the knee torque and hip torque generators respectively such that a reference point on the first leg not touching a ground surface follows a predetermined trajectory that is defined by at least one Cartesian coordinate, characterized in that a position of said reference point being determined from an orientation of the second leg which is in contact with the ground surface.