Development of operator interfaces for a heavy maintenance manipulator

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Development of operator interfaces for a

heavy maintenance manipulator

A dissertation submitted by

Peter Milani

BE(Mech), GradCert (EngTech), Dip. Pers Man

For the award of

Master of Engineering Research

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i. Abstract

This dissertation details the development of an intuitive operator interface for a complex serial manipulator, to be used in heavy maintenance tasks. This interface allows the operator to control the manipulator in the 'task-space', with software handling the conversion to 'joint-space'. Testing of the interfaces shows operator task-space control to be most effective in reducing operator workload and improving the ease of use of a complex machine. These methods are applicable in concept, to a wider range of manipulators and other machines.

A number of operator interfaces were developed: a Joystick Interface, a Master Arm interface and a 6-D Mouse Interface. The Joystick Interface made use of a task space to joint space transformation implemented in software. The Master Arm utilised a scale model to conduct the transformation. Finally, a 3D mouse Interface utilised sensors in an Android Device with a software based task to joint space transformation. These interfaces were tested and the Joystick Interface proved most suitable according to the operator's subjective opinion. Quantitative measurement also showed that it accurately reproduced the operator's commands.

The software transformation developed for the Joystick and 6-D Mouse interfaces utilised the Jacobian Matrix to complete the task-space to joint-space conversion. However, since the manipulator contained a redundant joint, an additional algorithm was required to handle the redundancy. This additional algorithm also improved manipulator safety, as it navigated the arm away from singularities which could result in large joint movement. The novelty of this algorithm is based on its pragmatic approach, and could be modified to achieve a number of safety or performance goals.

The control strategy centred on the operator specifying commands to the arm in the frame of the task. The developed algorithm enabled the control strategy by ensuring that viable solutions for joint velocity could be found in a manipulator that has redundant joints. Furthermore, this algorithm utilised a cost function that minimised the chances of large joint movements due to singularities, improving the safety of the device.

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ii. Certification

I hereby certify that the work contained in the dissertation is the bonafide work of myself and that the work has not been previously submitted for an award. To the best of the candidate's knowledge and belief, the dissertation contains no material previously published or written by another person except where due acknowledgement and reference has been made in the dissertation to that work.

Peter Milani Date:

Supervisor Signature:

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iii. Acknowledgements

The following people contributed to the development of the project:

Terry Milani, for assistance in the construction of the prototype and troubleshooting problems along the way.

David Patch, for educating the team about Dragline Maintenance and the initial proposer of the manipulator idea.

Brad Glenwright, for facilitating the site visits and assisting the team with experimental audiences and providing good feedback for the project.

Noel Zahra for support and championing of the project within BMA, particularly with the transition of the project from Norwich Park to Peak Downs Mine.

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iv.

Glossary

The following terms acronyms are used in this dissertation: 2D – two dimensional, describing a position on a plane 3D – three dimensional, describing a position in a volume

6D – six dimensional, describes position in a volume as well as orientation ADC – Analog to Digital Converter

CLK – Clock signal line in an SPI communications channel CPU – Central Processing Unit

CS, CSN – Chip Select line in an SPI communications channel

GAZEBO – the Gazebo robot simulation program by the Open Source Robotics Foundation

HMI – Human Machine Interface

HSEC – Health, Safety, Environment, and Community IOIO – ioio digital acquisition board for java programs JAVA – Java programming language

LCD – Liquid Crystal Display

MISO – Master In Slave Out line in an SPI communications channel MOSI – Master Out Slave In line in an SPI communications channel PID – Proportional Integral Derivative control methodology

PLC – Programmable Logic Controller PWM – Pulse Width Modulation ROS – Robot Operating System

SPI – Serial Peripheral Interface, a communications standard UI – User Interface

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Development of operator interfaces for a heavy maintenance manipulator