In this paper, we present a flatness-based robust adaptive tracking control for a mobile robot. In recent years, many cars are equipped with automatic driving systems. However, the design of control law for mobile robots is difficult because they are non-holonomic systems. To improve the safety of automatic driving, the control law considering robustness for mobile robots is required. In the conventional study for robust control, a robust adaptive tracking control is proposed for single input linear systems with matched disturbance and the simulation results shows its robustness and effectiveness. In addition, the conventional control law can be applied for nonlinear systems if the nonlinearity satisfies the matching condition. However, the conventional control law can't be applied for systems that has multiple input or its nonlinearity doesn't satisfy the matching condition. So the conventional control law can't be applied for a mobile robot because a mobile robot has two inputs and its nonlinearity don't satisfy the matching condition. Therefore, we linearize a mobile robot by flatness and regard the linear system as two single input linear subsystems. The conventional control law requires that the system matrix has the solution of Lyapnov equation, in other words, the system matrix is hurwitz. However, the system matrix obtained by flatness doesn't has the solution of Lyapnov equation. So, carefully to satisfy certain condition, we redesign a new system matrix which is hurwitz. As a result, we guarantee the stability considering robustness by dealing with the influence of the system matrix error as matched disturbance. Simulation results show the effectiveness of the proposed control law.

A transportation simulation of multiple objects to the appropriate goals by a robotic swarm has been performed with learning ability of the swarm. It is often observed that each insect in a colony seems to have its own agenda, and the group as a whole appears to be highly organized. By swarming, social insects achieve difficult tasks that an insect cannot manage alone. This collective behavior emerged from a group of social insects has been called “swarm intelligence”. Applications of swarm intelligence show high robustness and scalability, but, when it comes to applying to some intelligent task, the adjusting process of the parameters for a desired cooperative behavior may be a difficult, time-consuming task for a human designer. On the other hand, the artificial neural networks are known to have the learning ability. In this study, the swarm behavior in nature was simulated by “Boids” model. Boids model was known to be able to simulate the motion of a flock of birds by simple rules. Using this model, a cooperative transportation task has been simulated. The cooperative transportation task is to transport some objects by a swarm. In addition, the task of decision-making problem about transportation goal has been added. In this problem, the swarm of Boids makes a decision about the goal from the size of an object, considering each Boids as a unit of artificial neural networks, the network of Boids maps to the transportation destinations. Additionally, the back-propagation method has been applied to learn the appropriate goals. As a result, it is shown that the artificial swarm acquires the learning ability how to decide an appropriate goal for given objects.

This paper proposes a method to control vibrations of an automotive drive system which has backlash. Backlash of the differential gear in automotive drive systems exacerbates the vibration control performance. Concretely, a shock torque generated by dead zone band characteristics amplifies the vibration amplitude and prevents the model-based controller from suppressing transient responses completely. Especially, when engine torque changes drastically, torsional vibration is excited due to the backlash and disturbs driving performance and riding comfort. Therefore, it is necessary to develop a vibration control method to suppress the adverse effect due to backlash. The purpose of this research is to verify a convenient control logic suitable for implementation using experiments, which can evaluate the nonlinearity of backlash. In this study, a basic experimental device, which is dynamically equivalent to the original automotive drive system, is constructed to verify control systems. The structure of the device emphasizes the vibration problems due to backlash in actual vehicles. To design a model-based controller, functional modeling approach is applied for system modeling. Using this approach, a nonlinear system can be modeled in the form of a linear state equation. Then, a controller is designed based on the linear model-based controller. Regarding proposed compensation for backlash, a convenient control mode switching technique, which utilizes characteristics of actual vehicles such as a dead time, is applied to the model-based controller. Finally, the control system is verified by experiments using the basic experimental device.

This paper deals with simultaneous control between tilting and vibration of a railway vehicle using air springs. Conventional control system of railway vehicle has been carried out by a tilting control and a vibration control separately. In this research, equations of motion including coupling motion between tilting motion and vibration were formulated to realize the simultaneous control. Moreover, simultaneous controller using linear quadratic integral was designed. Control simulations using the simultaneous controller and the conventional controller were carried out. As the result, the good control performance was obtained by the simultaneous controller than the conventional controller.

This study proposes a vibration isolating bed for ambulance using an inerter. The structure of the bed is assumed to consist of the foundation fixed to the floor of the ambulance and movable table on which the stretcher is to be placed, the foundation and table are connected only by the suspension including the inerter in the direction of the foot and the left and right. Since the inerter can lower the gain of the high frequency band and delay the response, acceleration can be reduced in a limited space. We consider the bed as a plant and suspension as a controller, and we construct the state equation from this formulation. In order to reduce the acceleration within the movable range of the bed, the controller that minimizes the H_∞ norm of the transfer function from the external force acting on the foundation to the bed is calculated as a Bilinear matrix inequality (BMI) and we determine the structure and coefficient of the suspension from the transfer function. The usefulness of the proposed bed is verified from numerical simulations.

This paper takes up the issue of semi-autonomous control design in the crawler robots with sub-crawlers of the robot for disaster and we describe the issue of compliance control rotation angle of sub-crawler. Remote-controlled mobile robots are useful for searching around and inside buildings that have collapsed in a disaster. Disaster response robots should have high mobility on rough terrain. As widely known, the crawler robots with active sub-crawlers have the high traversability to get over on rough terrain. In the present circumstances, it is hard for the operator to control its active sub-crawlers in remote control. Therefore, operators must be well trained to achieve high mobility by using remote control. Because many researchers realize high traversability on foot performance by simple control for an operator, semi-autonomous control system is studied. On the other hand, a crawler robot with passive sub-crawlers is only necessary to control the movement direction and driving speed, unlike in the case of controlling active sub-crawlers. We have been examining ground adaptability of the ground adaptive crawler robot so far. As a result, it is known that the posture of the robot varies depending on the change in the angle of the sub-crawler of the robot and the shape of the obstacle, so that the roughness of the robot greatly affects the performance depending on the posture of the robot. In this paper, by modeling as a beam model, we try to interpret compliance as a problem of the length of the rod and the position of the center of gravity varying with the attitude of the crawler robot.

This paper presents a vehicle velocity control strategy for a mobile robot comprising two modules: a normal vehicle with wheels and auxiliary mass module to control the vehicle dynamics by changing the center of gravity. For this strongly nonlinear plant, the authors propose a vehicle velocity control applying input-output linearization together with integral sliding mode control to achieve robust performance in the presence of model uncertainties and disturbances. In addition, the resulting control system is analyzed in terms of the modelling error with respect to ground condition.

This paper presents a control strategy for a wheeled mobile robot with variable pitch blades which make it highly mobile over irregular terrain. In our previous work, a mathematical model with respect to pitching motion of the robot necessary to climb a stair was developed, and a servo controller for the pitching motion was proposed under the assumption that the desired lift and down force can be precisely generated without any delay. In this paper, taking the actuator dynamics into account, the controller is redesigned applying backstepping method, and its effectiveness is shown by numerical simulation.

A passive walker can walk down a slope without any actuators, using energy efficiently and with a natural walking style that is similar to that of any human. We may be able to manufacture an efficient walking robot if we investigate passive walking. This study investigates a passive walker having ankles and flat feet. First, we investigate the relation between the slope angle and gait; the higher the slope angle, the greater will be the step length and the walking speed. Second, we studied the relation between the ankle stiffness and gait; the greater the ankle stiffness, the shorter will be the contact time between the sole and the slope. The step length and walking speed also increased with an increasing ankle stiffness. However, when the ankle stiffness surpassed the threshold, the amount of changes in these parameters was observed to reduce. Further, the step period was constant despite changing the ankle stiffness and the slope angle.

In this study, a very small mass-spring system was constructed and its damping characteristic was studied experimentally. In the field of dynamics, the dominant theory will change depending on the size of an object. The mathematical model relevant to the motion of an object is called Newtonian dynamics, but it is only an approximation. Even in the case the size is not so small as governed by quantum mechanics, the influence of inertia, viscous force, or electro-static force will change when a dynamic system is miniaturized. Therefore, it is necessary to estimate these dynamic effects quantitatively to treat a very small physical system as represented by micro-machine. In this paper, a small mass-spring system was constructed and the free vibration experiment in the vacuum chamber was conducted to clarify its damping properties. The diameter of wire of the coil spring was around 20 μm, and the diameter of coil spring was around 400 μm. As a result, it was revealed experimentally that the air resistance is too large to ignore in micro scale.

Elucidation of the Moon and Mars environment is important for humans in pursuing space exploration. Moon and Mars exploration plans have previously existed, primarily adopting an excavation method using drills and scoops for soil sample collection mechanisms. Luna 16 (1970) excavated lunar soil using a drill and was the first unmanned mission to return it to Earth, and rovers Curiosity and Opportunity collected Mars soil using drills and scoops and analyzed it on-site. However, as this method is executed with mechanical remote control, its demerits include the requirement of accurate control, high malfunction risks, and the existence of many complex mechanical driving parts. We developed a particle sampling system using magnetic force since its control and mechanism are simpler, it is more reliable, and lunar and Mars soil are magnetic. High possibility of implementation is expected with the existence of past papers on flight phenomenon of magnetic particles due to magnetic force, and research plans of particle transportation on the Moon. Furthermore, we believe that our mechanism can be implemented as particle transportation device for ISRU (In-Situ Resource Utilization), which supposes future long-term manned missions to the Moon to generate water and oxygen from lunar regolith. This paper investigates the development of a multi-layer magnetic sampling and transportation system using multiple electromagnetic coils, which expects usage in space environment and long-distance transportation. We evaluated the system performance through 1-m length magnetic particle transportation experiments and particle behavior analysis using numerical calculations.

This paper proposes a hybrid type VTOL UAV which is constructed with a quad tilt rotor and a tailless wing for level flight. Tailless wing has a simple profile and a low cost production but also a low drag aerodynamics and enabling long endurance time in level flight. Previous paper shows the design concept of tailless wing that is combined with vertical wing for stability of the longitudinal motion and the reflex shape wing profile reducing pitching moment. The other hand a quadrotor system is already realized stable hovering and horizontal flight, and has suitable geometry to combine into the tailless wing. This paper develops VTOL tailless wing with quad tilt rotor for the rescue and surveying tasks. In order to demonstrate the VTOL performance 90°tilt mechanism is designed and installed into the fuselage. Control model in PX4 is compiled with the mixer file and source files as tailless VTOL with quad tilt rotor. Experimental result demonstrates the vertical take-off, the transition to horizontal flight, the high speed cruise, the transition to vertical flight and the landing.

This paper discusses a surveying methods using multi beam type 3D-LIDAR which is used for autonomous car and robots. In general, one beam type 3D Laser scanner is used, so it takes lot of time to measure. Authors developed swing mechanism for multi beam type 3D-LIDAR. In order to increase the scanning line between beam to beam. This mechanism validate for taking data at the stationary. As a method of creating maps by combining data acquired by this system, we report on the experiment of combining data by ICP.

Multistage tensegric robot arm is already presented to realize gigantic robot over 10m height. In the previous research, advantage of multistage robot to ease stress is confirmed and its control algorithm is discussed. However, its mechanical property has not been investigated yet. This paper discusses about mechanical properties, namely stress on cables and yielding load of the arm body, is theoretically investigated. These results would be useful to design real gigantic multistage robot arm.

Building a gigantic robot with ordinary structure is difficult because of the Square-cube law. Tensegric structure could be a suitable solution of building such gigantic robot. This paper deals with a novel robot arm based on the idea of Multi-Stage Tensegric structure. Two-dimensional Tensegric arm model taking the shape of frame and connecting wires into account is already presented, while three-dimentional behavior has not been investigated yet. Two type of wire tensioning are discussed, parallel or cross tensioning. Numerical simulation is carried out. It is shown that cross tensioning can ease wire stress than parallel tensioning.

A previous study has depicted that the behavior of the swinging leg before the walking collision is affected by the walking stability. Here, we consider a walking biped model with a torso and an actuator on the hip to control the torso and the swinging leg. The controller of this model uses an angular feedback as well as an angular velocity feedback. We analyzed the walking properties, such as stability, when the control gain was altered. We depicted that the desired torso angle and the angular feedback gain influenced the walking speed. We discovered that we can vary the degree of retraction during walking by changing the angular velocity feedback gain. If the gait is stable, the model returns to a periodic gait cycle when the angular velocity is perturbed immediately after the walking collision. From our analysis, we can conclude that appropriate protraction is the most stable.

Adaptive Cruise Control (ACC) system should be designed to behave like driver in various driving situations. We define the desired performance for ACC system as the “following” and the “approaching”. In the conventional control, it is difficult to design these performance independently. In this paper, we propose the new control structure. The proposed control has two controllers for each performance, and these controllers can be designed independently. It is demonstrated from the simulation results that the proposed control system achieves the desired performance in both “following” and “approaching” scene.

Currently, personal mobility vehicles (PMVs) are attracting attention as intermediate- or short-range transportation. Bicycles are familiar PMVs that are also environmentally friendly and convenient. A small-wheel bicycle saves space and is easy to carry. However, a small-wheel bicycle running at low speed has poor upright stability and maneuverability. The purpose of this study was to improve its running stability by adopting a steer-by-wire system, which independently operates the steering gear and driving tire. Sensors obtain the handle angle and actuators, instead of force from a mechanical connection, change the steering wheel angle. In this study, we carried out two experiments. First, we carried out straight running experiments to confirm the steering accuracy, upright stability, and maneuverability on a straight course. Second, we carried out turning experiments to confirm the upright stability and maneuverability on a course requiring changes in driving direction. It was confirmed that the proposed mechanism enhanced the upright stability compared with that of a conventional small-wheel bicycle. However, the maneuverability evaluations by the drivers showed that a conventional small wheel bicycle was better than the proposed steer-by-wire bicycle. The delay of motor control and the moment of inertia of the gearing might be the causes of this performance issue.

Antilock braking system (ABS) is used to control the damping force of a brake to prevent from locking. ABS based on a digital PID control law is most popular. However, the effectiveness of ABS is strongly dependent on the friction characteristic between a tire and a road surface. This characteristic changes every moment, while a vehicle moves. Therefore, the practical applicability of the conventional ABS is low. In this paper, a new ABS based on an accelerometer is proposed. First, both vehicle and wheel velocity are acquired in real time and a slip ratio is continuously calculated from these data. Second, the maximum value of accelerometer within a definite period of time is calculated, this slip ratio obtained at this moment is defined as a reference value of a slip ratio. Finally, a vehicle is controlled by the conventional PID control so that this reference value of a slip ratio is kept. The reference value changes with time. Simulation results show that the effectiveness of the proposed ABS with PID control is verified; since the stopping distance becomes shorter than the case of a conventional ABS. Therefore, the proposed method is easily implemented due to simple architecture and low cost.