scholarly journals A grid gradient approximation method of energy-efficient gait planning for biped robots

2021 ◽  
Vol 18 (2) ◽  
pp. 172988142110043
Author(s):  
Lu Zhiqiang ◽  
Hou Yuanbing ◽  
Chai Xiuli ◽  
Meng Yun
Keyword(s):  
Energy Consumption ◽  
Energy Efficient ◽  
Joint Angle ◽  
Body Motion ◽  
Gradient Descent Method ◽  
Biped Robots ◽  
Gait Planning ◽  
Zero Moment Point ◽  
Zero Moment ◽  
Efficient Gait

In this article, an energy-efficient gait planning algorithm that utilizes both 3D body motion and an allowable zero moment point region (AZR) is presented for biped robots based on a five-mass inverted pendulum model. The product of the load torque and angular velocity of all joint motors is used as an energy index function (EIF) to evaluate the energy consumption during walking. The algorithm takes the coefficients of the finite-order Fourier series to represent the motion space of the robot body centroid, and the motion space is gridded by discretizing these coefficients. Based on the geometric structure of the leg joints, an inverse kinematics method for calculating grid intersection points is designed. Of the points that satisfy the AZR constraints, the point with the lowest EIF value in each network line is selected as the seed. In the neighborhood of the seed, the point with the minimum EIF value in the motion space is successively approximated by the gradient descent method, and the corresponding joint angle sequence is stored in the database. Given a distance to be traveled, our algorithm plans a complete walking trajectory, including two starting steps, multiple cyclic steps, and two stopping steps, while minimizing the energy consumption. According to the preset AZR, the joint angle sequences of the robot are read from the database, and these sequences are adjusted for each step according to the zero-moment-point feedback during walking. To determine the effectiveness of the proposed algorithm, both dynamic simulation and walking experiment in the real environment were carried out. The experimental results show that compared with algorithms based on the fixed body height or vertical body motion, our gait algorithm has a significant energy-saving effect.

scholarly journals Energy-Efficient Train Driving Strategy with Considering the Steep Downhill Segment

Processes ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 77 ◽  
Author(s):  
Wentao Liu ◽  
Tao Tang ◽  
Shuai Su ◽  
Jiateng Yin ◽  
Yuan Cao ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Energy Efficient ◽  
Solution Space ◽  
Descent Method ◽  
Urban Rail Transit ◽  
Gradient Descent Method ◽  
Transit Systems ◽  
Classical Energy ◽  
Urban Rail ◽  
Save Energy

Implementation of energy-efficient train driving strategy is an effective method to save train traction energy consumption, which has attracted much attention from both researchers and practitioners in recent years. Reducing the unnecessary braking during the journey and increasing the coasting distance are efficient to save energy in urban rail transit systems. In the steep downhill segment, the train speed will continue to increase without applying traction due to the ramp force. A high initial speed before stepping into the steep downhill segment will bring partial braking to prevent trains from overspeeding. Optimization of the driving strategy of urban rail trains can avoid the partial braking such that the potential energy is efficiently used and the traction energy is reduced. This paper presents an energy-efficient driving strategy optimization model for the segment with the steep downhill slopes. A numerical method is proposed to calculate the corresponding energy-efficient driving strategy of trains. Specifically, the steep downhill segment in the line is identified firstly for a given line and the solution space with different scenarios is analyzed. With the given cruising speed, a primary driving strategy is obtained, based on which the local driving strategy in the steep slope segment is optimized by replacing the cruising regime with coasting regime. Then, the adaptive gradient descent method is adopted to solve the optimal cruising speed corresponding to the minimum traction energy consumption of the train. Some case studies were conducted and the effectiveness of the algorithm was verified by comparing the energy-saving performance with the classical energy-efficient driving strategy of “Maximum traction–Cruising–Coasting–Maximum braking”.

Multi-level control of zero-moment point-based humanoid biped robots: a review

Robotica ◽  
2015 ◽  
Vol 34 (11) ◽  
pp. 2440-2466 ◽  
Author(s):  
Hayder F. N. Al-Shuka ◽  
B. Corves ◽  
Wen-Hong Zhu ◽  
B. Vanderborght
Keyword(s):  
Control Strategies ◽  
Humanoid Robots ◽  
Human Locomotion ◽  
Level Control ◽  
Biped Robots ◽  
Zero Moment Point ◽  
Cluttered Environments ◽  
Multi Level ◽  
Zero Moment ◽  
Autonomous Humanoid

SUMMARYResearchers dream of developing autonomous humanoid robots which behave/walk like a human being. Biped robots, although complex, have the greatest potential for use in human-centred environments such as the home or office. Studying biped robots is also important for understanding human locomotion and improving control strategies for prosthetic and orthotic limbs. Control systems of humans walking in cluttered environments are complex, however, and may involve multiple local controllers and commands from the cerebellum. Although biped robots have been of interest over the last four decades, no unified stability/balance criterion adopted for stabilization of miscellaneous walking/running modes of biped robots has so far been available. The literature is scattered and it is difficult to construct a unified background for the balance strategies of biped motion. The zero-moment point (ZMP) criterion, however, is a conservative indicator of stabilized motion for a class of biped robots. Therefore, we offer a systematic presentation of multi-level balance controllers for stabilization and balance recovery of ZMP-based humanoid robots.

Control of walking robots based on manipulation of the zero moment point

Robotica ◽  
2000 ◽  
Vol 18 (6) ◽  
pp. 651-657 ◽  
Author(s):  
K. Mitobe ◽  
G. Capi ◽  
Y. Nasu
Keyword(s):  
Control Method ◽  
Walking Robots ◽  
Control Law ◽  
Real Time Control ◽  
Biped Robots ◽  
Zero Moment Point ◽  
Time Control ◽  
Point Control ◽  
Zero Moment ◽  
Robot Body

In this paper, a new application of the ZMP (Zero Moment Point) control law is presented. The objective of this control method is to obtain a smooth and soft motion based on a real-time control. In the controller, the ZMP is treated as an actuating signal. The coordinates of the robot body are fed back to obtain its position. The proposed control method was applied on two different biped robots, and its validity is verified experimentally.

Design of a Biped Toy Robot with an Automatic Center of Gravity Shifting Mechanism

2010 ◽  
Vol 118-120 ◽  
pp. 670-674
Author(s):  
Pai Shan Pa ◽  
Jinn Bao Jou
Keyword(s):  
Degrees Of Freedom ◽  
Biped Robot ◽  
Center Of Gravity ◽  
Biped Robots ◽  
Zero Moment Point ◽  
Single Motor ◽  
Mechanical Products ◽  
Zero Moment ◽  
Crank Mechanism

The design of the biped toy robot in this study, presents a brand new concept compared to that of the conventional mechanical biped robots on the market. These conventional mechanical products rely mainly on a large sole area to stabilize the wobbling movement during walking. In this design walking stability is not achieved by large sole areas, but by having more degrees of freedom and automatically shifting the center of gravity as the robot walks. A single motor is used to drive the biped toy robot trunk so that the center of gravity is automatically shifted to achieve walking stability. The two feet are driven by four connecting rods for striding and leg-lifting action. More particularly, an equal parallel crank mechanism is provided that uses a single motor to drive the connecting rods, thereby swinging the center of gravity of the toy robot in time with striding frequency. In addition, the concept of the zero moment point is utilized in the shifting of the center of gravity allowing the biped robot to lift its legs, change step, and move forward in balance. This study also discusses the use of the four connecting rods, and the shifting of the center of gravity of the robot, as an alternative to the servomotors commonly used in conventional robots which are bulky, expensive and hard to control.

Rotational Stability Index (RSI) point: postural stability in planar bipeds

Robotica ◽  
2010 ◽  
Vol 29 (5) ◽  
pp. 705-715 ◽  
Author(s):  
Goswami Dip ◽  
Vadakkepat Prahlad
Keyword(s):  
Postural Stability ◽  
Stability Index ◽  
Rotational Stability ◽  
Stability Criteria ◽  
Flat Foot ◽  
Biped Robots ◽  
Zero Moment Point ◽  
Foot Posture ◽  
Zero Moment ◽  
The Stability

SUMMARYThe postural stability of bipedal robots is investigated in perspective of foot-rotation during locomotion. With foot already rotated, the biped is modeled as an underactuated kinematic structure. The stability of such biped robots is analyzed by introducing the concept of rotational stability. The rotational stability investigates whether a biped would lead to a flat-foot posture or the biped would topple over. The rotational stability is quantified as a ground reference point named “rotational stability index (RSI)” point. Conditions are established to achieve rotational stability during biped locomotion using the concept of the RSI point. The applicability of the RSI point is illustrated through experimentation for the landing stability analysis of the bipedal jumping gaits.The traditional stability criteria such as zero-moment point (ZMP) [M. Vukobratovic and B. Borovac, “Zero-moment point – thirty five years of its life,” Int. J. Humanoid Robot. 1(1), 157–173 (2004)] and foot-rotation indicator (FRI) [A. Goswami, “Postural stability of biped robots and the foot-rotation indicator (FRI) point,” Int. J. Robot. Res. 18(6), 523–533 (1999)] are not applicable to analyze biped's postural stability when foot is already rotated. The RSI point is established as a stability criteria for planar bipedal locomotion in presence of foot rotation.

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