Safety and Productivity Advantages of Using Remote Control Technology to Operate Construction Machinery
By Dr. Friederike Brendel and Jeff Allan, Construction Executive
Controlling machinery via radio communication offers many safety advantages, such as the ability to operate equipment from safer grounds and with better vantage points, and at reduced levels of noise or vibration. In turn, this allows for greater ease of machine operation, less operator fatigue, and increased efficiency and productivity. On the other hand, radio remote control brings about its unique characteristics related to the physical properties of radio transmission and wireless control, such as limited range and signal coverage, coexistence with other radio users, or battery life.
Radio systems can be used in any application where there is an advantage for the operator to have the freedom of movement, including concrete pumping trucks where operators can position themselves at the end of the boom, tower cranes where the operator can directly work with the load and drilling equipment where the operator can be safely removed from hazardous activities. Other examples include truck cranes, rock crushers, paving machinery, wheel loaders and bulldozers. In general, radio control is realizing a higher rate of adoption in numerous industries and is now being applied to an even wider range of applications and activities. As a result, the demand for broader customization is rapidly increasing.
By working directly with a number of international original equipment manufacturers (OEMs), the radio control interface can be optimized as a quality extension of the machine. For some OEMs, the use of remote controls has become a necessity rather than an option. With the remote-control system being the main human interface to control the equipment, and in many cases the only touchpoint for their customers, machine manufacturers rely on products that can match their quality and durability requirements.
Long-term partnerships with machine manufacturers are crucial to offering the highest level of reliability with solutions that best fit the operator’s ergonomics and working conditions. Functional safety concepts are usually addressed in an early stage, as they determine much of the underlying structure of the radio remote control system. As part of a risk analysis, some of the key questions to be answered when equipping a piece of construction machinery with a safe remote control system are:
- What is the safe state of the machine?
- How is the emergency stop signal processed on the machine or at the interface between radio receiver and machine?
- How should the machine react in case of a radio signal drop-out?
- Is it beneficial for the machine control to differentiate between a stop following a signal drop-out, and an active stop signal triggered by the operator?
- Are there other safety-relevant functions?
The primary safety function is usually the emergency stop function, as it enables the operator to take the machine into a safe state immediately. However, depending on the specific needs of the application, additional safety-relevant considerations may be necessary. In the context of machine control, safety functions can be assessed according to different normative concepts, such as the Safety Integrity Level (SIL) or the Performance Level (PL). The specification of a performance level is a first indicator of the reliability of a radio remote control system—or, more precisely, its safety concept. Most technical standards for construction machinery require a performance level “d” for the emergency stop function, implying that the theoretical probability of a dangerous failure of this function is at most 10-6 per hour (i.e., only one failure occurring in at least 114 years).
When designing a safety function, it is crucial to consider the whole signal chain from the operating element (e.g., a joystick on the operator’s console) to the respective actuator on the machine, and all of the hardware and software in the chain. In order to achieve the required level of safety, the design of the interface between radio receiver and the machine becomes a critical issue. Here is where applications and operators benefit most from a strong partnership between machine and radio manufacturers.
For applications where feedback and machine diagnostics are critical, multiple transmitters can be equipped with innovative, configurable color displays. With this option, the operator can access live machine feedback data during operation, such as oil pressure, wind speed, load weight and sling length, to name a few. Another innovation allows a video camera to be mounted in an ideal position, where it can then wirelessly supply the operator with live video feeds back to the control—giving the operator greater visibility of his or her working environment. In short, access to relevant information on the job enables the operator to make the right decisions at the right moment, which is the key to increasing productivity.