Table 1. During a complete test procedure, i.e. observation, each of tasks 1–8 were repeated four times in the order shown. Only the first two of four identical repetitions (rep.), i.e. the first half of complete test procedures, are shown below. Task numbers 8 were later removed from the dataset. Consequently, four repetitions of task numbers 1–7 constituted one complete observation for statistical analyses. In column ‘Act’, ‘Incl.’ = task included in the study, ‘Excl.’ = task completely excluded from the study.
Task Description Act Rep.
1 Red log lifted from the ground and placed in the load-space. Incl. 1
2 Boom steered from the load-space, without holding any log in the grapple, to the blue log on the ground. Incl.1
3 Blue log lifted from the ground and placed in the load-space. Incl.
4 Boom steered from the blue log – within the load-space, and without holding any log in the grapple – to the red log. Incl.1
5 Red log lifted from the load-space and placed on the ground. Incl.
6 Boom steered from the ground, without holding any log in the grapple, to the blue log in the load-space. Incl.1
7 Blue log lifted from the load-space and placed on the ground. Incl.
8 Boom returned, without holding any log in the grapple, back to the red log, i.e. starting position. Excl.
1 Red log lifted from the ground and placed in the load-space. Incl. 2
2 Boom steered from the load-space, without holding any log in the grapple, to the blue log on the ground. Incl.1
3 Blue log lifted from the ground and placed in the load-space. Incl.
4 Boom steered from the blue log – within the load-space, and without holding any log in the grapple – to the red log. Incl.1
5 Red log lifted from the load-space and placed on the ground. Incl.
6 Boom steered from the ground, without holding any log in the grapple, to the blue log in the load-space. Incl.1
7 Blue log lifted from the load-space and placed on the ground. Incl.
8 Boom returned, without log held in the grapple, back to the red log, i.e. starting position. Excl.
Etc. … … …
1 Exception: tasks 2, 4, 6 were excluded from the dependent variable clearance. For more information, see Fig. 1, Panel: B.
1

Fig. 1. Panel A. Test procedure comprised fixed positions for logs (blue and red), both in the load-space and on the ground. During a complete observation, the logs were repositioned in a predetermined way several times (Table 1). Panel B. Boom-tip paths were mathematically reconstructed later, based on the crane geometry and collected raw data. A visualised reconstruction example here represents one complete observation.

2

Fig. 2. In all panels: black squares correspond to the conventional boom control (CBC) and grey balls to the Intelligent Boom Control (IBC); standard deviations are given in parentheses after the means; ticks on x axes correspond to the given point of time 1, 2, 3 and 4. Panel A, y axis: total time per complete observation [10 seconds]. Panel B, y axis: total distance travelled by boom tip [100 metres]. Panel C, y axis: average number of simultaneous functions of the joystick in use during a complete observation. Panel D, y axis: vertical clearance [m] between the top of the bunk stake and the lowest point of grapple. Panel E, y axis: number of directional changes of the joystick [×1000]. More detailed descriptions of the depended variables are given in Section 2.1. Note that the ranges on the y axes also vary in relative terms.