Masamiki Kawase

Walking up and down stairs carrying a human by a biped locomotor with parallel mechanism

This paper describes the means of tuning-up method of the walking parameters to go up and down stairs for a biped robot with leg mechanisms using Stewart platforms. It has been confirmed that the stroke range of use could be reduced by tuning up the waist yaw trajectory and preset ZMP trajectories for motion pattern generation. By using the developed method, a walking experiment involving movement up and down a stair with the rise of 250 mm and certain walking experiments ascending and descending stairs carrying a human were successfully completed. Through these experiments, the effectiveness of the proposed method was confirmed.

Biped landing pattern modification method with nonlinear compliance control

Many researchers have been studied on acceleration control algorithms for biped robots to deal with uneven terrain. However, the control algorithms are difficult to be used for human-carrying biped walking robots because of modeling errors. In this paper, a landing pattern modification method is proposed which based on nonlinear compliance control. Theoretical compliance displacements calculated from a walking pattern are compared with the actual compliance displacements, while a robots foot touches slightly uneven terrain. In result, the height of landing terrain is detected, and the preset walking pattern is modified. Using this method, a human-carrying biped robot would be able to walk stably on uneven terrain. This pattern modification method does not need any special sensors except force sensors. Through various walking experiments, the effectiveness of the method is confirmed

Realization by Biped Leg-wheeled Robot of Biped Walking and Wheel-driven Locomotion

Biped walking is easily adaptable to rough terrain such as stairs and stony paths, but the walk speed and energy efficiency on the flat ground is not so effective compared with wheeled locomotion. In this paper, we propose a biped robot to be able to walk or wheel according to the ground conditions. For wheeled locomotion, WS-2 (Waseda Shoes -No. 2) is developed which is composed of a DC motor, a spherical caster and two rubber pads on each foot. WS-2 is attached to the feet of WL-16 (Waseda Leg -No. 16) that is the worlds first biped-walking robot capable of carrying a human. Also, a path planning for wheeled locomotion is presented. Through hardware experiments, the effectiveness of this foot module is confirmed.

Walking Control Method of Biped Locomotors on Inclined Plane

This paper describes a walking control method on inclined planes for a biped locomotor. The walking control consists of a position control, virtual compliance control and posture control. Parameters of the compliance control are changed continuously in support and swing phases. The orientation of robot’s waist is kept level by posture control. Several walking experiments on inclined planes are conducted using WL-16R (Waseda Leg - No. 16 Refined). WL-16R has achieved stable walking on unknown inclined planes using the walking control method, and the effectiveness of the walking control is confirmed.

New Foot System Adaptable to Convex and Concave Surface

Many control methods have been studied on the assumption that the feet of biped robots contact the ground with four points. However, it is difficult for almost all of such biped robots to maintain four-point contact on uneven terrains because they have rigid and flat soles. In order to solve the problem, foot mechanisms should be studied. In 2003, we developed WS-1R (Waseda Shoes - No.1 Refined) which is able to maintain four-point contact. However, it is difficult to deal with the concave or convex ground because of the problems of the contact detection and sideways slip. So, WS-5 (Waseda Shoes - No.5) has been developed. To avoid the slip of the foot, a cam-slider locking system consisting of a solenoid and a cam is constructed and installed at the foot. Also, linear encoders are employed to measure the position of the foot sliders. Through walking experiments on uneven terrains, the effectiveness of WS-5 is confirmed.

Support torque reduction mechanism for biped locomotor with parallel mechanism

This paper describes the development of the support torque reduction mechanism for a biped locomotor with leg mechanisms using Stewart platforms, designed for heavy payload and low power consumption during walking. The basic design of this mechanism was decided through preliminary experiments. Each leg of the robot is equipped with this mechanism consisting of 2 gas springs with different reaction forces, which are switched according to the swing/support phase. The experiment measuring motor current during walking with payload and the walking experiment with maximum payload confirmed the effectiveness of this mechanism.

Realization of Stable Biped Walking on Public Road with New Biped Foot System Adaptable to Uneven Terrain

To date, many control methods have been researched on the assumption that the soles of a biped walking robot contact the ground as four points. It is difficult for almost all biped robots to maintain four-point-contact on uneven terrain because they have rigid and flat soles. It means that the biped robots can lose their balance. To solve this kind of problem, not only stability controls but also foot mechanisms should be studied. So, we developed a foot system, WS-1 (Waseda Shoes - No.1) that can maintain four-point-contact on uneven terrain, different from conventional foot systems. However, since WS-1 has some problems, an improved foot system, WS-1R (Waseda Shoes - No.1 Refined) is developed. Through hardware experiments, the effectiveness of WS-1R is confirmed

Landing Pattern Modification Method with Predictive Attitude and Compliance Control to Deal with Uneven Terrain

Many researchers have been studying on walking control methods for biped robots. However, the effectiveness of these control methods was not verified in outdoor environments such as pedestrian roads and gravel roads. In this paper, a landing pattern modification method adaptable to uneven terrain in a real environment is proposed which is based on a predictive attitude compensation control and a nonlinear compliance control. This method does not require any other sensors except force sensors. Also, a new biped foot system is described which can form larger support polygons on uneven terrain than conventional biped foot systems. Using the modification method and the foot system, WL-16RII (Waseda Leg-No.16 Refined II) achieved a stable walk on bumpy terrain with 20 mm height and 10 degrees inclination. Furthermore, a stable dynamic walk was realized on a paved road, when a human rode it. Through various walking experiments, the effectiveness of the method was confirmed

Development of foot system of biped walking robot capable of maintaining four-point contact

To date, many control methods have been studied, assuming that the soles of a biped walking robot contact the ground as four points. It is difficult for a biped robot with rigid and flat soles to maintain four-point contact on uneven terrain. It means that the biped robot can lose its balance. To solve this kind of problem, we should study not only stability control methods but also foot mechanisms. In this paper, a new foot system, WS-1 (Waseda shoes

Development of a Biped Locomotor with the Double Stage Linear Actuator

no.1), is proposed to maintain four-point contact. This foot system consists of cam-type locking mechanism. WS-1 is attached to the feet of WL-16 (Waseda leg - no.16) that is the worlds first biped-walking robot capable of carrying a human. Through hardware experiments, the effectiveness of the foot system is confirmed.