Posture Control for Personal Mobility Robot Using Feedback Compensation with Unstable Pole

Abstract

SUMMARYThis paper presents a novel posture control approach using feedback compensation with an unstable pole. For a narrow and small personal mobility robot (PMR), this is needed in order to control its posture for achieving quick turning and high acceleration. However, in the conventional control approach that uses the posture angle as a controlled variable, the zero moment point (ZMP) does not settle to the desired point in the following cases: an unknown disturbance force given to the PMR, a fluctuation in the center of gravity of the PMR, and a change in the conditions between the tires and the road surface. In this paper, a novel control method using feedback compensation with an unstable pole is proposed to achieve the desired ZMP in the steady state. The proposed controller changes the control input for the actuator of posture control to zero in order to achieve the desired posture angle. The effectiveness of the proposed approach is verified through experiments using a prototype of the PMR. C⃝ 2015 Wiley Periodicals, Inc. Electr Eng Jpn, 193(1): 33-42, 2015; Published online in Wiley Online Library (wileyonlinelibrary.com).

Posture Stabilization Control of Personal Robot Based on Model Predictive Control

“…Here, c 1 , c 2 , c 3 , c 4 , c 5 , and c 6 are as follows: Thus, if the predictive model in Eqs. (21) and (23) is used, then the predicted value for the state at the N p step can be represented using an affine function of the input signal Δu[k] at the N u step.…”

“…Thus, we have developed the robot in Fig. 1 to follow a person and carry his/her belongings [4][5][6][7][8]. Walking for 30 min several times per week is reported to contribute to maintaining health and improving quality of life [9].…”

“…In Refs. [5], [6], and [10] through [13], methods to achieve both (1) and (2) by actively controlling the roll angle of the robot are proposed. However, what is primarily given attention in these methods is only posture control in the steady state.…”