1 Introduction
2 Methodology
3 Theoretical background
3.1 Characterizing automation
1. | Human does it all |
2. | Automation offers alternatives |
3. | Automation narrows alternatives down to a few |
4. | Automation suggests a recommended alternative |
5. | Automation executes alternative if human approves |
6. | Automation executes alternative; human can veto |
7. | Automation executes alternative and informs human |
8. | Automation executes selected alternative and informs human only if asked |
9. | Automation executes selected alternative and informs human only if it decides to |
10. | Automation acts entirely autonomously |
3.2 Problems and challenges in human-automation collaboration
3.3 Automation interface
4 Case studies
4.1 Background
4.2 Case 1: assembly of flywheel housing cover (FWC)
No. | Characteristic | Case study 1 | Case study 2 |
---|---|---|---|
1. | No. of operators | 3–4 | 1 |
2. | Cycle time | 4 min (approx) | 1 min (approx) |
3. | Part description | Rigid cast-aluminium, 20 kg | Flexible and plastic, \(<1\) kg |
4. | Part dimension \(l \times w \times d\) | 1 m \(\times\) 1 m \(\times\) 0.4 m | 1.5 m \(\times\) 0.5 m \(\times\) 0.1 m |
5. | Nature of workstation | Stop and go station | Continuously moving line |
4.3 Case 2: assembly of under-body car panels (UBP)
5 Result
5.1 Assembly of flywheel housing cover (FWC)
5.2 Assembly of under-body panels (UBP)
No. | Measures to reduce risk | Safety function |
---|---|---|
1. | Physical fences | A physical barrier between human and a hazard zone that requires deliberate actions to enter a hazardous space. It can support compliance of safety and deter automation misuse |
2. | Light curtain, laser scanner, pressure sensitive mats | Sensitive protective equipment (SPE) monitors a 2D space and can trigger a removal of power from a hazard zone when an intrusion is detected. They can be muted to allow entry to the monitored area |
3. | Enabling switches | A mechanism to allow operators to carry out tasks collaboratively and safely. There are three positions, where position one and three will result in a safety stop and in position two, the robot can move as intended |
4. | Mode-change button | Mode-change button signals that the collaborative task is complete and the system can safely change to automatic mode |
5. | Reset button and start button | A reset button will clear and reset safety signals that allows the robotic system to continue from its current position. A start button is used to clear all safety signals after an emergency or protective stop has been issued |
6. | Floor marking and other visual aids | As humans cannot precisely judge their surrounding area, floor marking helps them to recognize the boundary of the collaborative workspace |
6 Discussion
6.1 Safety during automatic mode
No. | ED/MD | Initiating collaborative mode | Initiating non-collaborative mode |
---|---|---|---|
1. | No ED, with MD | Laser scanner mutes and lights turns green. Operator enter CW and fastens screws | Operator exit CW, disengage MD which activates laser scanner. Robot immediately moves to robot workspace |
2. | With ED, no MD | When ED is engaged, laser scanner mutes, green light flashes, operator enters CW and fastens screws | Operator exit CW and disengage ED, which activates laser scanner, green light turns red. Robot continues to the end of the line and then moves to robot workspace |
3. | No ED, no MD | Laser scanner mutes and the red lights turns green. Operator enter CW and fastens screws | Operator exit CW. Robot continues to the end of the line which activates laser scanner. When the green light turns red, robot moves to robot workspace |