This paper presents the design and evaluation of the LOPES exoskeleton robot, a gait rehabilitation device that combines a freely translatable and 2-D-actuated pelvis segment with a leg exoskeleton containing three actuated rotational joints: two at the hip and one at the knee. The joints are impedance-controlled to allow bidirectional mechanical interaction between the robot and the training subject. The device allows both "patient-in-charge" and "robot-in-charge" modes, where the robot follows or guides the patient, respectively. Electromyography (EMG) measurements show that free walking in the device closely resembles treadmill walking, indicating its potential for task-specific gait training. However, position measurements are not accurate enough for inverse-dynamical gait analysis. The LOPES robot is designed to allow near-normal free walking and provide a wide range of training content while ensuring safety. It features eight actuated degrees of freedom (DOFs), including two for horizontal pelvis translation and three rotational joints per leg. The robot is impedance-controlled, using position sensing combined with force actuation. The exoskeleton is physically connected to an actuated support at pelvis height, allowing for weight compensation and external corrective forces. The robot uses Bowden-cable driven series elastic actuators for low weight "pure" force sources. The prototype uses Kollmorgen/Danaher AKM22C servomotors, Neugart Planetary gearheads, and Linmot linear actuators. The robot is tested with hardware tests and EMG measurements, showing that free treadmill walking and walking in the LOPES device are similar. The robot's performance is evaluated in terms of force and torque measurements, and the results indicate that the device can provide a wide range of force and torque capabilities. The robot's orientation and position are measured to ensure accurate control and use as a measurement device. The results show that the LOPES robot is a functional and safe gait rehabilitation device, capable of providing task-specific gait training and supporting various training modes. However, further research is needed to improve the accuracy of position measurements for inverse-dynamical gait analysis.This paper presents the design and evaluation of the LOPES exoskeleton robot, a gait rehabilitation device that combines a freely translatable and 2-D-actuated pelvis segment with a leg exoskeleton containing three actuated rotational joints: two at the hip and one at the knee. The joints are impedance-controlled to allow bidirectional mechanical interaction between the robot and the training subject. The device allows both "patient-in-charge" and "robot-in-charge" modes, where the robot follows or guides the patient, respectively. Electromyography (EMG) measurements show that free walking in the device closely resembles treadmill walking, indicating its potential for task-specific gait training. However, position measurements are not accurate enough for inverse-dynamical gait analysis. The LOPES robot is designed to allow near-normal free walking and provide a wide range of training content while ensuring safety. It features eight actuated degrees of freedom (DOFs), including two for horizontal pelvis translation and three rotational joints per leg. The robot is impedance-controlled, using position sensing combined with force actuation. The exoskeleton is physically connected to an actuated support at pelvis height, allowing for weight compensation and external corrective forces. The robot uses Bowden-cable driven series elastic actuators for low weight "pure" force sources. The prototype uses Kollmorgen/Danaher AKM22C servomotors, Neugart Planetary gearheads, and Linmot linear actuators. The robot is tested with hardware tests and EMG measurements, showing that free treadmill walking and walking in the LOPES device are similar. The robot's performance is evaluated in terms of force and torque measurements, and the results indicate that the device can provide a wide range of force and torque capabilities. The robot's orientation and position are measured to ensure accurate control and use as a measurement device. The results show that the LOPES robot is a functional and safe gait rehabilitation device, capable of providing task-specific gait training and supporting various training modes. However, further research is needed to improve the accuracy of position measurements for inverse-dynamical gait analysis.