In this paper, we designed an attitude controller for a quadcopter based on sliding mode control. Autonomous flight experiments on a straight line path were conducted in the outdoors. The control performance of the conventional PID control method and the sliding mode control method designed in this paper was compared at a wind speed of 3 m/s. In the case of PID control, the maximum errors of the lateral direction, roll angle, pitch angle, and yaw angle were 34.6 cm, 2.59 deg, 5.61 deg, and 15.02 deg, respectively, on the other hand, in the case of sliding mode control, they were 20.5 cm, 1.49 deg, 1.43 deg, and 5.62 deg, respectively. Therefore, under a wind speed of 3.0 m/s, the results of position and attitude angle errors indicate that sliding mode control is effective in improving the robustness of the system.

To improve the productivity of individuals, this study proposes a method to identify stress, which is also divided into positive or negative one. The method takes features in the time course into account. The paper presents important variables to estimate stress states. Whether the proposed method can identify stress states is confirmed through experiments, whose details are explained in the paper. The paper also discusses how to use non-invasive and low-cost wearable sensors along with the method.

During walking with trans-femoral prostheses, lower limb amputees have risks of tripping due to knee bending, in which the knee joint unexpectedly flexes. Since the trips lead to serious injuries such as broken bones, knee bending affects daily life quality. In recent years, robotic technology has been used to develop trans-femoral prostheses that don’t cause the knee bending. In general, in order to avoid tripping, even when the foot contact the ground with the knee joint in flexion, it is important to return to normal walking after stepping on the prosthetic leg. However, since the conventional robotic prostheses doesn’t control the flexion angle of the knee joint that enables the prevention of tripping, they have risks of tripping when the amputees unexpectedly lost their balance. Therefore, in this study, we constructed trip-avoidance strategy based on a mathematical formulation of the flexion angle of the prosthetic knee joint according to the assumed knee bending pattern during walking and designed a new knee bending prevention system for robotic knee prostheses. Finally, we conducted experiments that simulate knee bending by a user of trans-femoral prosthesis and showed the effectiveness of proposed method.