Automation can address labor shortage and enhance worker safety in construction. However, workers continue to perform majority of the work at construction sites that can be automated. Construction machinery require force control for automation, which can absorb external shocks and provide appropriate forces along with environmental forces. This study proposes a force-controlled excavator that fulfills these requirements by replacing the hydraulic system with a series elastic actuator (SEA). Few studies have applied SEA to large high-output construction machinery. We designed the structure of the SEA to deliver high output power in a compact form that can be mounted on an excavator. A 2.5-T class excavator equipped with this SEA is designed, which achieved a force resolution of 15–35 N at the tip. The effectiveness of this excavator in automating a major portion of the manual work is demonstrated.

We develop a flying robot with a new pantograph-based variable wing mechanism for horizontal-axis rotorcrafts (cyclogyro rotorcrafts). A key feature of the new mechanism is to have a unique trajectory of variable wings that not only change angles of attack but also expand and contract according to wing positions. As a first step, this paper focuses on demonstrating the possibility of the flying robot with this mechanism. After addressing the pantograph-based variable wing mechanism and its features, a simulation model of this mechanism is constructed. Next, we present some comparison results (between the simulation model and experimental data) for a prototype body with the proposed pantograph-based variable wing mechanism. Both simulation and experimental results show that the flying robot with this new mechanism can generate enough lift forces to keep itself in the air. Furthermore, we construct a more precise simulation model by considering rotational motion of each wing. As a result of optimizing design parameters using the precise simulation model, flight performance experimental results demonstrate that the robot with the optimal design parameters can generate not only enough lift forces but a 155 gf payload as well.

We develop a flying robot with a new pantograph-based variable wing mechanism for horizontal-axis rotorcrafts (cyclogyro rotorcrafts). A key feature of the new mechanism is a unique trajectory of variable wings that not only change angles of attack but also expand and contract according to wing positions. Experimental results show that the developed flying robot can generate 144% lift force for its own weight (equivalently 100 gf payload). Furthermore, as a result of optimizing design parameters of the robot through computer simulation, we arrive at the optimal design parameters with 200 gf payload. Both simulation and experimental results show the utility of the developed flying robot with the new mechanism.

A new method of estimating coding peak signal-to-noise ratio (PSNR) without the use of reference signals is presented. Although PSNR is commonly used as a measure of the picture degradation of digitally coded video, the calculation requires source signals as a reference.Therefore, the usage of PSNR is restricted to particular applications or systems. The proposed method enables PSNR estimation based on the probability density functions of quantized discrete cosine transform (DCT) coefficients extracted from an MPEG-2 bit stream. We experimented with MPEG-2 video coding bit streams under varying quantization scheme and evaluate a new method with comparing estimated PSNRs with actual PSNRs. Experimental results indicate that the determination coefficients are higher than 0.9 This method can apply to both SDTV and HDTV, and can evaluate PSNR of every frame coded by different picture types.