Ground level service access to logging machines has become commonplace.

One of the most interesting new technologies being developed in forest engineering is monitoring the fatigue and concentration of machine operators.

By Andrew McEwan
andrew@cmo.co.za

We are well aware that long shifts, especially at night, can result in operator fatigue. This does not only result in accidents due to a lapse in concentration, but also machine damage and a loss of productivity.

Technologies have been developed in the automotive industry that track where the operator is looking and can detect when a driver/operator is distracted or nodding off to sleep. An alarm is triggered that gets their attention back to the task or serves as a reminder to take a rest.

However, it is often off-site activities that result in fatigue at the workplace. Being able to determine how rested an operator is when he/she arrives at the worksite allows machine owners to proactively manage this risk.

Technology such as wrist warn actigraphy allows this off-site information to be collected and the data can be used along with in-cab data to determine the fatigue risk. However, there are ethical boundaries as to how much off-site intrusion into an operator’s personal life can take place.

Considering the fact that operator fatigue is one of the biggest safety and productivity risks, these technologies hold much potential.

All loggers are aware of the dangers posed by people or machines being too close to other machines. Even though this risk is well known and training and on-site risk assessments focus on this, there are still an unacceptably high number of incidents and accidents which take place. Forestry machines, especially tracked machines, have restricted visibility from the cab. If a person or machine approaches this machine and is not in the operator’s field of vision, then there is a high risk of contact taking place due to machine slewing or movement.

People or machines entering the blind spot of operators in large logging machines are problematic.

This is also a problem in the mining and construction industries due to the size of the machines. These industries have realised that training and risk assessments alone are not sufficient to mitigate the risk.
Technologies such as cameras, proximity sensors (radar and camera) and GPS are used to monitor machines and people and their proximity to each other. The technology either provides the operator with awareness for the blind spots and hazard proximity (e.g. cameras and monitor screens), or senses the machines and people as they approach and warns the operator of the danger.

Connectivity between machines also assists by communicating the danger without operator intervention.

Another common source of injuries is when the operator or maintenance technician is climbing on or off the machine, or working on the machine. Technologies being developed provide more ground level access for components which need regular attention, minimising the requirement to climb onto the machine. There will be improved ergonomic paths for machine mounting, dismounting and maintenance. This will include foot and hand positions and non-slip surfaces. The covers of areas such as the engine compartment will be opened by electric motors thus eliminating the need for people to exert themselves in a high risk position.

Many technologies are being developed to either improve the stability of machines, or to make the operator aware that a machine is at the limits of its capabilities when working on steep slopes.

Inclinometer and accelerator sensors determine when a danger point is being reached regarding machine instability before the operator is even aware of the risk. Dynamic stability systems prevent machine tip-over by monitoring the forces at play and learn the machine’s limits based on load dynamics, height, weight, slope and speed. A computer will automatically stop the machine when danger thresholds are reached.

Even a system of shifting counterweights at the rear of excavators to balance the forces that cause machine instability, has been considered. However the cost is prohibitive.

Stability control systems are increasingly being developed to keep machines and operators safe.

What is beginning to emerge on wheeled machines is chassis levelling. Current seat and cabin levelling options on wheeled machines assist with operator ergonomics, but do little to improve stability, as the centre of gravity is not changed. Technology that is able to level the chassis through hydraulic cylinders will create increased stability.

Of course the final safety technology intervention to protect operators is to remove them from the machine completely, especially under high risk conditions such as steep slopes.

The clearest trend is a move towards tele-operation, whereby the operator is separated from the machine in a safe location and remotely operates the machine from there. This technology is becoming quite common in mining environments but the data processing requirements for a forest environment is more complex.

In order to remotely control a logging machine, a full tele-operational command and control platform needs to be stationed close enough to allow adequate communication with the machine. The system must supply situational awareness and provide relevant operation information (e.g. fuel levels, temperatures, pressures) to the operator.

It will probably be some time before tele-operations become cost competitive and it will only be used in high risk areas.

Automation allows the machine to carry out certain tasks – or all tasks – independently of the operator. The use of robotics is now possible due to the sensors that are available (e.g. 3D laser, GPS, stereo camera, 3D cameras, inertial measurement unit, and odometry). It is now also possible to combine information from multiple modalities, and machine learning of tasks is possible.

Portable computing makes it possible to perform many advanced tasks in real-time. However, automated tasks (path following) require good localisation. Therefore a good map is needed for localisation (digital terrain models) and it is far more productive if the exact location of the tree is known. Technology such as LiDAR, vision and GPS can be used to create these maps. However the development of this technology in a forestry application is expensive and could take time.

Non-slip surfaces and adequate handles are critical for safe cab entry and exit.

*First published in SA Forestry magazine, April 2017