This paper proposes the prediction error observer (PEOB) for the design of networked predictive control systems (NPCSs) with network delays and model errors, which is based on the stability criteria for closed-loop NPCSs. In the NPCSs, a prediction error occurs due to model errors. Based on a-priori predictions, the PEOB compensates for the prediction error when the controller predicts the current and future states. The proposed method improves the performance of the conventional NPC associated with network delays and model errors. Experimental results illustrate the effectiveness of the proposed control strategies.
This study deals with a robot hand based on the original finger mechanism consisting of a planetary gear system and serially connected four bar linkages. It also has a mechanism for adjusting stiffness of fingers (VSM: Variable Stiffness Mechanism), which allows to give passive gripping force to a gripping object according to the object's elasticity. The mechanism is merely driven by mechanical elements without sensory feedback from tactile or force sensors attached to fingertip or sole. The total number of motors for driving the robot hand is six, all of which are equipped in the palm. Rotation angle of motor is detected by optical encoder equipped to each motor. The robot hand achieves soft and adaptive gripping action due to VSM that adjusts the joint stiffness of the fingers by changing tension of the spring attached to the planetary gear system equipped in every finger except the thumb. Driving tests show that it achieves typical gripping and pinching motions of a human hand in daily life without any sensory feedback and also show that the VSM works effectively.
We introduce the stable walking system for the large 6 legged walking machine. The machine was developed to realize a solid and reliable walking vehicle for practical uses in forestry steep terrain with spread mechanical elements those are used in usual construction machines. It weighs about 4,000[kg] including the working machine. Owing to a mounted diesel engine and hydraulic drive system, it can walk around on the soft soil terrain and climb the steep slope of inclination up to about 30 degrees, and walk along contour line of lateral inclination up to about 41 degrees. Finally it walked well, despite it was tested on severe steep terrain where a lot of shrubs and stumps exist. We tested and evaluated the machine mainly about its significant walking method, hydraulic motion control system for walking and real-time inclination correcting system.