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Article
Publication date: 21 August 2009

Fei Wang, Chengdong Wu, Xinthe Xu and Yunzhou Zhang

The purpose of this paper is to present a coordinated control strategy for stable walking of biped robot with heterogeneous legs (BRHL), which consists of artificial leg…

Abstract

Purpose

The purpose of this paper is to present a coordinated control strategy for stable walking of biped robot with heterogeneous legs (BRHL), which consists of artificial leg (AL) and intelligent bionic leg (IBL).

Design/methodology/approach

The original concentrated control in common biped robot system is replaced by a master‐slave dual‐leg coordinated control. P‐type open/closed‐loop iterative learning control is used to realize the time‐varying gait tracking for IBL to AL.

Findings

The new control architecture can simplify gait planning scheme of BRHL system with complicated closed‐chain mechanism and mixed driving mode.

Research limitations/implications

Designing and constructing a suitable magneto‐rheological damper can greatly improve the control performance of IBL.

Practical implications

Master‐slave coordination strategy is suitable for BRHL stable walking control.

Originality/value

The concepts and methods of dual‐leg coordination have not been explicitly proposed in single biped robot control research before. Master‐slave coordinated control strategy is suitable for complicated BRHL.

Details

Industrial Robot: An International Journal, vol. 36 no. 5
Type: Research Article
ISSN: 0143-991X

Keywords

Article
Publication date: 20 June 2016

Lei Wang, Yongde Zhang, Shuanghui Hao, Baoyu Song, Minghui Hao and Zili Tang

To eliminate the angle deviation of magnetic encoder, this paper aims to propose a compensation method based on permanent magnet synchronous motor (PMSM) sensorless…

Abstract

Purpose

To eliminate the angle deviation of magnetic encoder, this paper aims to propose a compensation method based on permanent magnet synchronous motor (PMSM) sensorless control. The paper also describes the experiments performed to verify the validity of this proposed method.

Design/methodology/approach

The proposed method uses PMSM sensorless control method to get high precision virtual angle value, and then get the deviation value between virtual position and magnetic angle which is used as compensation table. Oversampling linear interpolation tabulation method has been proposed to eliminate the noise signals. Finally, a magnetic encoder with precision (repeatability) 0.09° and unidirectional motion precision 0.03 is realized. The control system with an encoder running at 14,000 and 0.01 r/min showing high motion resolution is also realized.

Findings

Higher value of current in PMSM leads to a magnetic encoder with higher precision. When using oversampling linear interpolation to tabulate the compensation table, it is understood that more oversampling does not lead to a better result. Finally, validated by experiments, using eight intervals to calculate the mean value of angle deviation leads to the best result.

Practical implications

The angle deviation compensation method proposed in this paper has a great practical implication and a good commercial application. The method proposed in this paper could be effectively used to self-correct the magnetic encoder using arctangent method and also correct any rotary encoder sensor.

Originality/value

This paper originally proposes an adaptive correction method for a rotary encoder based on PMSM sensorless control. To eliminate the noise signals in an angle compensation table, over-sampling linear interpolation tabulation method has been proposed which also guarantees the precision of the compensation table.

Details

Sensor Review, vol. 36 no. 3
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 1 September 1999

Olivia Yu and Lening Zhang

Studies suggest that official crime statistics are more than a measure of criminal activity. Generated by police, crime figures also reflect the behavior and concerns of…

1237

Abstract

Studies suggest that official crime statistics are more than a measure of criminal activity. Generated by police, crime figures also reflect the behavior and concerns of police. Our case study renders evidence to this argument. A national survey of the crime recording by police was conducted in China in the late 1980s and early 1990s. The results reveal significant under‐representation of crime in the police‐produced statistics and clearly identify the police as the source of errors. Our study presents the survey and examines the findings. We explore systemic and social factors that affect the underpresentation problem and assess possible impact of the findings on the police’s action in crime recording.

Details

Policing: An International Journal of Police Strategies & Management, vol. 22 no. 3
Type: Research Article
ISSN: 1363-951X

Keywords

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