
Figure 1.
3D crane
Table 1.
State and control variables of the mathematical model
| Variable | Description |
|---|---|
| x1 | Position X axis [m] |
| x2 | Linear velocity X axis [m/s] |
| x3 | Position Y axis [m] |
| x4 | Linear velocity Y axis [m/s] |
| x5 | Angular deviation between lifting rope and Y axis [rad] |
| x6 | Angular velocity for x5 [rad/s] |
| x7 | Angular deviation between the negative direction on the Z axis and the projection of the lifting rope onto the XZ plane [rad] |
| x8 | Angular velocity for x7 [rad/s] |
| x9 | Position Z axis [m] |
| x10 | Linear velocity Z axis [m/s] |
| u1 | PWM control signal for DC motor in X axis [-] |
| u2 | PWM control signal for DC motor in Y axis [-] |
| u3 | PWM control signal for DC motor in Z axis [-] |
Table 2.
Constant parameters of the 3D crane model
| Parameter | Variable | Value |
|---|---|---|
| Load weight | mc | 1 kg |
| Boogie weight | mw | 1.155 kg |
| Bus weight | ms | 2.2 kg |
| Friction force axis X | Tx | 100 N |
| Friction force axis Y | Ty | 82 N |
| Friction force axis Z | Tz | 75 N |

Figure 2.
Test control signal

Figure 3.
Position of load

Figure 4.
Angular deviation of load

Figure 5.
The structure of 3D crane control system with 5 PID controllers

Figure 6.
The structure of 3D crane predictive control system
Table 3.
Proposed gains of PID controllers
| No. | PID X | PID Y | PID Z | PID A | PID B |
|---|---|---|---|---|---|
| 1 | kp = 33 ki = 0.4 kd = 0 | kp = 41 ki = 0.1 kd = 0 | kp = 50 ki = 0.2 kd = 0 | kp = 0 ki = 0 kd = 0 | kp = 0 ki = 0 kd = 0 |
| 2 | kp = 33 ki = 0.4 kd = 0 | kp = 41 ki = 0.1 kd = 0 | kp = 50 ki = 0.2 kd = 0 | kp = 10 ki = 0.2 kd = 0 | kp = 10 ki = 0.3 kd = 0 |
| 3 | kp = 33 ki = 0.4 kd = 0.2 | kp = 41 ki = 0.1 kd = 0,32 | kp = 50 ki = 0.2 kd = 0.1 | kp = 15 ki = 0.2 kd = 0.05 | kp = 17 ki = 0.3 kd = 0.2 |
Table 4.
IAE for PID controllers
| No. | x1 | x3 | x9 | x5 | x7 | Sum |
|---|---|---|---|---|---|---|
| 1 | 0.3451 | 0.345 | 0.253 | 0.1945 | 0.3759 | 1.513 |
| 2 | 0.342 | 0.3646 | 0.253 | 0.1164 | 0.248 | 1.324 |
| 3 | 0.3413 | 0.3788 | 0.253 | 0.1077 | 0.2022 | 1.283 |
Table 5.
ISE for PID controllers
| No. | x1 | x3 | x9 | x5 | x7 | Sum |
|---|---|---|---|---|---|---|
| 1 | 0.02403 | 0.04063 | 0.01387 | 0.003578 | 0.01483 | 0.09693 |
| 2 | 0,02398 | 0,04076 | 0,01387 | 0,00133 | 0,005404 | 0,08534 |
| 3 | 0,02402 | 0,04096 | 0,01387 | 0,001256 | 0,003864 | 0,08397 |
Table 6.
Weight values for NMPC controller
| No. | w1 | w2 | w3 | w4 | w5 | w6 | w7 | w8 |
|---|---|---|---|---|---|---|---|---|
| 1 | 1000 | 1000 | 1000 | 0 | 0 | 0.001 | 0.001 | 0.001 |
| 2 | 1000 | 1000 | 3000 | 0.03 | 0.03 | 0.01 | 0.01 | 0.01 |
| 3 | 1000 | 1000 | 3000 | 0.03 | 0.03 | 0.0005 | 0.0005 | 0.0005 |
| 4 | 1000 | 1000 | 3000 | 1 | 1 | 0.001 | 0.001 | 0.001 |
Table 7.
IAE for NMPC controller – tuning the weight values with constant Hp
| No. | x1 | x3 | x9 | x5 | x7 | Sum |
|---|---|---|---|---|---|---|
| 1 | 0.3249 | 0.35 | 0.3904 | 0.0874 | 0.4617 | 1.614 |
| 2 | 0.3742 | 0.4531 | 0.3978 | 0.1022 | 0.4505 | 1.778 |
| 3 | 0.3243 | 0.3507 | 0.2591 | 0.08956 | 0.4705 | 1.494 |
| 4 | 0.3227 | 0.5025 | 0.2551 | 0.08911 | 0.5194 | 1.689 |
Table 8.
ISE for NMPC controller – tuning the weight values with constant Hp
| No. | x1 | x3 | x9 | x5 | x7 | Sum |
|---|---|---|---|---|---|---|
| 1 | 0.02347 | 0.04116 | 0.02141 | 0.0008966 | 0.02083 | 0.1078 |
| 2 | 0.02349 | 0.04272 | 0.01805 | 0.001013 | 0.01973 | 0.105 |
| 3 | 0.02347 | 0.04171 | 0.01386 | 0.00092 | 0.02129 | 0.1013 |
| 4 | 0.02353 | 0.0463 | 0.01375 | 0.0008992 | 0.02578 | 0.1103 |
Table 9.
IAE for NMPC controller – tuning the control horizon Hp
| Hc. | x1 | x3 | x9 | x5 | x7 | Sum |
|---|---|---|---|---|---|---|
| Hc=2 | 0.3335 | 0.3589 | 0.3007 | 0.09413 | 0.4805 | 1.568 |
| Hc=4 | 0.3243 | 0.3507 | 0.2591 | 0.08956 | 0.4705 | 1.494 |
| Hc=6 | 0.326 | 0.3552 | 0.2607 | 0.08828 | 0.4496 | 1.48 |
Table 10.
ISE for NMPC controller – tuning the control horizon Hp
| Hc | x1 | x3 | x9 | x5 | x7 | Sum |
|---|---|---|---|---|---|---|
| Hc=2 | 0.02313 | 0.04175 | 0.01481 | 0.0009334 | 0.02222 | 0.1028 |
| Hc=4 | 0.02347 | 0.04171 | 0.01386 | 0.00092 | 0.02129 | 0.1013 |
| Hc=6 | 0.0236 | 0.04202 | 0.01357 | 0.0009144 | 0.01989 | 0.09999 |

Figure 7.
Obtained waveforms of tracking reference trajectory x1 for both designed control systems

Figure 8.
Obtained waveforms of tracking reference trajectory x3 for both designed control systems

Figure 9.
Obtained waveforms of tracking reference trajectory x9 for both designed control systems

Figure 10.
Obtained waveforms of x5 control for both designed control systems

Figure 11.
Obtained waveforms of x7 control for both designed control systems
