Granular tapioca was thermally blended with poly(lactic acid) (PLA). All blends were prepared using a plasti-corder and characterized for tensile properties, thermal properties and morphology. Scanning electron micrographs showed that phase separation occurred, leading to poor tensile properties. Therefore, methylenediphenyl diisocyanate (MDI) was used as an interfacial compatibilizer to improve the mechanical properties of PLA/tapioca blends. The addition of MDI could improve the tensile strength of the blend with 60 wt% tapioca, from 19.8 to 42.6 MPa. In addition, because PLA lacked toughness, acetyl tributyl citrate (ATBC) was added as a plasticizer to improve the ductility of PLA. A significant decrease in the melting point and glass-transition temperature was observed on the basis of differential scanning calorimetry, which indicated that the PLA structure was not dense after ATBC was added. As such, the brittleness was improved, and the elongation at break was extended to several hundred percent. Therefore, mixing ATBC with PLA/tapioca/MDI blends did exhibit the effect of plasticization and biodegradation. The results also revealed that excessive plasticizer would cause the migration of ATBC and decrease the tensile properties.

The rapid prototyping technique has been developed over several decades. As the application becomes more widespread, the qualities of the parts produced by a rapid prototyping system must be considered. The area-forming rapid prototyping system is an emerging technology. This system has the advantage of a short build time but displays a weakness in the dimensional accuracy and surface roughness. To improve these weaknesses and simultaneously maintain a short build time, this study optimizes the process parameters using the grey relational Taguchi method. From the results, the best combinations of process parameters both for each quality and for multiple qualities are discovered. The optimization of process parameters is verified using the extra samples.

As part of compliant motion control for a robot arm, the force sensor is usually installed at the wrist of the robot arm to measure the force/moment caused by the external force and the load (the end-effector and the extra object). The robot arm will fail to achieve the desired compliance if the effect of the load is not considered. In this study, a strategy of joint position-based impedance control with load compensation method for the robot arm is proposed, even if the load is unknown. It will distinguish between the external force and the gravitational effect of the load in compliant motion control. Experimental results show that the proposed control method can successfully remove the effect caused by the load, and the robot arm performs compliant motion correctly, in accordance with the impedance characteristic.

The randomized Hough transform (RHT) is a useful tool to locate patterns in an image. In this study, we propose a modified RHT to detect circles/circular arcs efficiently. First, we segment an image into sub‐images based on edge information, then we use the proposed circular arc analysis and density check rule to modify RHT for circle/circular arc detection. In the experiments, real images are used to show the capability of the proposed method.