Traditional Cruise Control vs Adaptive Cruise Control
Traditional Cruise Control.
Most drivers are familiar with this basic cruise control which can only maintain set speed. The driver determines the desired speed and then switches on the cruise control to maintain that current speed. The cruise control disengages once the driver presses any of the car's paddles; namely the accelerator, brake or clutch.
- it takes over the routine depression of the accelerator from the driver.
- improves fuel efficiency of the motor vehicle by avoiding uneven acceleration.
- it is generally easy to use after reading the manual or brief training.
- need for continual resetting of cruising speed once it is disengaged.
- unsafe braking distances with the leading car as drivers try to avoid disengaging and resetting the cruise control.
- lack of mode awareness i.e. drivers often forgot which speed they were travelling in as shown by hard braking and travelling over allowed zone speed limits.
Adaptive Intelligent Cruise Control.
The AICC is mostly managed by exception whereby the driver sets the required following gap and set the braking options. It operates semi-autonomously by maintaining the following gap and light braking when the lead vehicle reduces speed. The driver however intervenes in cases that require heavy braking, needs to adjust the speed according to road set limits or decides to operate the speed controls manually.
Additionally, the deceleration is only down to a specified speed thus the driver must come back into the loop and take over the speed controls of the vehicle.This system is called by different names such as adaptive cruise control, intelligent cruise control and others call it autonomous cruise control.The car uses sensors to detect the lead vehicle and maintains the following speed using complicated algorithm calculations.
- It significantly reduces workload by taking over monotonous task such as accelerator pedal depression.
- The reduction of speed by the cruise control depending on the leading vehicle reduces rear end collisions.
- it reduces vehicle wear and tear through smooth acceleration or braking.
- It may reduce physical workload but significantly increase mental workload since the system requires constant monitoring.
- Many authors are now beginning to suggest that under load can be at least as detrimental to performance as overload (Young & Stanton, 2002).
- AICC can end up causing under load which leads to poor reaction by the driver in cases of emergency due to depleted attentional resources
Countering the shortfalls
- Mental workload caused by AICC can be reduced by providing auditory feedback so that it does not compete with the visual resources required for the motor vehicle direction control. This explains why navigation systems with auditory feedback are safer to use than visual ones.
Challenges in assessing the usability of AICC.
Primary Behavioural Techniques
These are based on the assumption that performance degrades as workload increases. The number of errors committed when the driver is using an AICC or not are evaluated. If more errors are committed when drivers are not using the AICC it implies that the AICC has addon advantages on driving accuracy.
However, such techniques may not be used to evaluate driving workload in real situations in which any mistake can be catastrophic or fatal. Exposing subjects to dangerous situations is not ethical for example the British Psychological Ethics guidelines clearly stipulates that such studies can not be sanctioned. Without an objective measurement on how the AICC may reduce or balance both cognitive and physical workload its efficacy remains questionable.
Secondary behavioural techniques
The proponents of such techniques posit that demands on cognitive resources by a primary task may lead to poor performance on a secondary task. Such techniques include telling the driver to answer audio questions while performing a driving task with the AICC's assistance or without AICC and then comparing the number of errors made under each condition. The more the errors, the more the cognitive load.
Although they are useful, like their counterparts discussed above they are too intrusive to be used on drivers in real life situations.
Driver self reports
These are more feasible , safe and cheap to administer. The methods include questionnaires or interviews to assess the driver's perceived cognitive overload soon after completion of the driving task.
Self reports are often subjective and drivers may report having experience little cognitive overload to protect their self esteem. The recency effect on memory may lead to drivers only remembering incidents that occurred in the last lap of the driving task thereby offering a biased overall assessment of what happened throughout the task.
Subject Matter Experts (SEMS) observe drivers as they perform the task, ask questions and write notes on observed behaviour which will be used to assess cognitive or behavioural overload. Hard breaking, traveling above stated speed limits, not checking blind spots and so forth will be recorded as indicators of overload. The number of errors between participants using the AICC and those driving without assistance of the AICC.
There is danger of the Hawthorne effect (people behave differently when being observed). We all likely to drive differently in front of a marked traffic police car. Drivers may drive differently to please the observers. Observers are not spared from human weaknesses such as sympathising with the driver and not recording errors judged as unavoidable.
They include measurement of heart rate, blood pressure and so forth on the assumption that higher scores indicate high driving overload. They tend to be relatively easy to collect and do not intrude on task performance.
However, they are not diagnostic (you cannot tell what causes any increase/decrease in driver's workload) and are often confounded by other factors not related to task demands. High temperatures may lead to increased heart rate and increased blood pressure, which implies that relating such increases to driver's workload will be misleading.
Both the traditional and adaptive cruise controls are useful in reducing driver's workload if used according to the manufacturer's specifications. They can both take over the strenuous depressing of the vehicle's accelerator on long journeys. Users need to be made aware of the limitations of these motor vehicle speed regulators to reduce accidents likely to be caused by driver-cruise control interaction errors. There is need for more advanced testing measures to assess the safety of using such devices and improve the user interface. This is my opinion, you express yours by participating in the poll below or entering a comment in the box below the poll.