In this paper, an integrated ankle torque sensor and mechanism (Foot Link) of a Tendon driven-type wearing walking aid robot were designed. The foot link consists of an ankle torque sensor and a mechanism connected to the footrest. The size of the sensing part of the ankle torque sensor was designed through structural analysis and assembled by attaching a strain gauge. As a result, the reproducibility error and the nonlinearity error were within 0.04%, respectively. And the calibration result of the ankle torque sensor, reproducibility error, and non-linearity error were identified to be within 1%, respectively. Therefore, it is proposed that the ankle torque sensor presented in this paper can be used to measure the torque acting on the tendon-driven walking aid robot.

In this paper, the design and fabrication of the calf-link with knee joint torque sensor of a tandem-driven walking-assist robot is described. Tendon-driven walking-assist robots should be designed and constructed with a wire wheel and a torque sensor, as one body to reduce the weight of the calf link. The torque sensor consists of four plate sensing parts crossed 90° around the wire wheel. Structural analysis was performed to determine the size of the torque sensor sensing part, and a torque sensor was built by attaching a strain gauge to the sensing part. As a result of the characteristics test, the reproducibility error and the nonlinearity error of the manufactured torque sensor were less than 0.03% and 0.04%, respectively. As a result of the calibration, the reproducibility error and the nonlinearity error were less than 0.08%, respectively. Thus, it is considered that the knee joint torque sensor of the calf link can be attached to the tandem-driven walking-assist robot.

In this paper, we designed and fabricated a hip joint torque sensor that can measure the torque applied to the hip joint of a walking assistant robot that can be used by a leg patient. To do this, we modeled the structure of the hip joint torque sensor so that it can be connected to the thigh link and the body of the walking assist robot. We calculated the rated torque of the hip joint torque sensor using computer simulation and determined the size of the torque sensor using a finite element program. The hip joint torque sensor was made by constructing a Wheatstone bridge and attaching a strain gauge. The characteristic test of the fabricated torque sensor was performed using a calibration device, and the reproducibility error and the nonlinearity error of the torque sensor were both less than 0.04%. Therefore, it is proposed that the developed hip joint torque sensor can be attached to the thigh link of the wearable walking assist robot, and the torque sensor can accurately measure the torque applied to the hip joint.