Time-optimal control of robotic manipulators with limit heat characteristics of the actuatorMa, Shugen
doi: 10.1163/15685530260174502pmid: N/A
In this paper, we present a time-optimal control scheme for a robot manipulator to track a predefined geometric path, subject to constraints due to the limit heat characteristics of the actuator (the DC motor was assumed to be the actuator used). Constraints due to the rated torque bounds and the rated velocity bounds of the motor would not be valid for continuous use of the manipulator, since the required mechanical output of the actuator (DC motor) exceeds its maximum power capacity and greatly exceeds its heat-converted power limit. The heat-converted power of the DC motor is thus considered as the actuation bound and the time-optimal trajectories are generated subject to this bound. Computer simulation was also executed to demonstrate the effectiveness of the proposed scheme in comparison to former schemes that used the rated torque and the rated velocity.
Final-state control of a two-link cat robotWeng, Zhiqiang; Nishimura, Hidekazu
doi: 10.1163/15685530260174511pmid: N/A
In this study, we deal with the twisting motion of a falling cat robot by means of two torque inputs around her waist. The cat robot consists of two rigid columns and has two internal actuators at the joint to generate torque inputs around normal coordinates. This system is a nonholonomic system whose angular momentum is conserved. We formulate the state equation that has torque inputs to the joint by using the nonholonomic constraint and the Lagrange-d'Alembert principle. Then, we transform the system into a linear parameter varying system. In order to improve error learning of a final-state control method, we provide the initial inputs in order to determine the appropriate rotation direction in the early stage of the twisting motion. Next, we introduce the method of the artificial potential function to the final-state control in order to make the maximum bending angle small. The feedforward torque inputs can be obtained by the final-state control in order to bring the system from the initial state to the final state in the desired time. In simulations, we also demonstrate that the twolink cat robot can land on her feet by using the 2-d.o.f. control system even when her waist damping coefficient varies.
Robust motion control with the consideration algorithm of joint torque saturation for a redundant manipulatorOhishi, Kiyoshi; Nozawa, Hideo
doi: 10.1163/15685530260174520pmid: N/A
As each joint actuator of a robot manipulator has a limit value of torque, the motion control system should consider the torque saturation. In order to consider the torque saturation in a transient state, this paper proposes a new redundant motion control system using the autonomous consideration algorithm on torque saturation. A Jacobian matrix of a redundant robot manipulator can select the optimal one considering its motion energy in the steady state. When the motion control system carries out fast motion and quick disturbance suppression, a high joint torque is required in a transient state. In the experimental results, under the condition of having a large payload torque and a fast motion reference, the proposed redundant manipulator control realizes the quick robot motion robustly and smoothly.
Stabilization control for biped follow walkingLim, Hun-Ok; Yamamoto, Yousuke; Takanishi, Atsuo
doi: 10.1163/15685530260174539pmid: N/A
This paper proposes a follow-walking motion for biped humanoid robots based on a stabilization control and a complete walking-motion pattern. To follow human motion, the unit patterns of the trunk, the waist and the lower limbs are generated and synthesized. During the follow motion, the biped robots are balanced by the stabilization control that calculates the combined motion of the trunk and the waist that compensates for the moments produced by the motion of the lower limbs. For confirmation of the follow-walking motion, we have developed a life-sized humanoid robot, WABIAN-RII (WAseda BIped humANoid robot-Revised II). It has a total of 43 mechanical d.o.f.; two 6-d.o.f. legs, two 10-d.o.f. arms, a 4-d.o.f. neck, 4-d.o.f. in the eyes and a torso with a 3-d.o.f. waist.