Haruyuki Yoshida

Mobile manipulation of humanoids-real-time control based on manipulability and stability

A real-time control method for a humanoid in mobile manipulation, doing tasks with its arms while moving, is proposed. The arm tips always follow their desired position with external force applied by impedance control, for carrying out a given task with the arms. An evaluation function consisting of not only stability but also arm manipulability-both are important for mobile manipulation-is defined; the humanoid controls its body and legs so that this evaluation may be optimal. As a result, the humanoid autonomously steps or keeps standing, coordinating with the arm tips motion. The effectiveness and usefulness of the proposed method are ascertained by computer simulations on a humanoid of human-size and experiments using a small experimental robot.

Mobile manipulation of humanoid robots-optimal posture for generating large force based on statics

The optimal posture of a humanoid robot for generating large desired force at its hands is discussed. The robot is required to stand stably and to support the force and its weight under the constraint of maximum joint torques. Furthermore, it is important to keep the robot controllable against sudden change in the force. From this point of view, an evaluation function for the task with large force based on statics is proposed; we focus on Jacobian matrices of two arms and legs to give the robot adaptability to force change. Then the method of obtaining the optimal posture, footholds and joint torques of the robot is described. Effectiveness of the method are verified through computer simulations.

Mobile manipulation of humanoid robots-a method of adjusting leg motion for improvement of arm's manipulability

A control method of mobile manipulation for a humanoid robot by integrated motion centered arm manipulation is proposed. This method makes the arms carry out the manipulation, and the legs assist manipulation by adjusting its motion in order to keep the arms manipulability high. Firstly, the arm tips always follow their desired position under the condition with external force by impedance control. Secondly, the shoulder is controlled so that manipulability and stability can be improved. Moreover, we define three functions; they are an average of manipulability measure, and an average and a minimum of stability margin in a locomotion cycle. We utilize their values in a locomotion cycle rather than the values of them at every moment, because manipulability and stability vary with robot motion. Then, we define the total evaluation function expressed by the sum of them. Step length and timing of step motion are determined so that the function can be optimized. The effectiveness of the proposed method is ascertained through the computer simulations.

Mobile Manipulation of Limbed Robots — Proposal on Mechanism and Control —

Abstract Two proposals on mobile manipulation of “limbed robots”-defined as robots which have both arms and legs-are described. 1) “Limb Mechanism”, using one linkage for both legged locomotion and arm manipulation, enlarges arms working space and augments arms versatility in mobile manipulation. Based on this concept, a six-limb robot is developed. 2) Coordinating with the arm motion for performing objective tasks, the legs autonomously change some motion patterns such as standing and stepping; that enables dexterous, stable and efficient manipulation by the arms. This control method is applied to humanoid robots, which have two arms and two legs.

Mobile manipulation of humanoid robots-analysis of manipulability and stability in mobile manipulation

This paper describes mobile manipulation of humanoid robots. A humanoid robot is a kind of integrated machines: two arm and two leg mechanism. It could be well applied to mobile manipulation in nonroutine task automation. The main objective of the mobile manipulation is to obtain versatile and efficient manipulation by the arms. In this respect the legs are required to assist the arms obtaining their high manipulability by changing step length and timing of step motion. Accordingly, the required motion of the legs in mobile manipulation is different from conventional biped locomotion. From this point of view, the relationship between manipulability of the arm and various leg motions is analyzed and evaluated by computer simulations.