A robotic joint comprises a first link, a middle link, a torque generator, a second link, and a locking mechanism. Different ends of the middle link are rotatably coupled to the first link and the second link. The torque generator is coupled to the first link and the middle link and is configured to produce torque between these links. The locking mechanism is switchable between a locking state and an unlocking state. In the unlocking state, the locking mechanism allows free rotation of the second link relative to the middle link in the first and second rotation directions. In the locking state, the locking mechanism is configured to impede rotation of the second link relative to the middle link in the first rotation direction and to allow rotation of the second link relative to the middle link in the second rotation direction opposite of the first rotation direction.