Background
Current development process and MBD/UM for HCD
Problems of current development process
Aim and approach
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To reduce time and cost required to produce the hardware of the product sample at evaluation.
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To evaluate the product by simulation, under various conditions and also repeatedly under the same condition.
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To eliminate risks injuring test participants in the evaluation, and to reduce the risks in the certification.
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Understand and specify the context of use by Persona. Persona can describe both a profile of a stakeholder and a context of use of a product. Therefore, Persona can be effective to understand and to specify the context of use.
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Specify the user requirements by MBSE. MBSE can define user requirements for a product, and models of product and stakeholder as diagrams, drawn based on the profile of stakeholder and the context of use. Therefore, MBSE can be effective to specify the user requirements and the models of product and stakeholder.
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Produce design solutions to meet user requirements for MBS on RTM. MBD can produce design solutions for MBS with a device model of product and UM of stakeholder by using RTM, based on the user requirements and the models. Therefore, MBD can be effective to produce design solutions to meet user requirements.
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Evaluate the designs against requirements by MBS on RTM. MBD can evaluate the design solutions against the user requirements by MBS with the device model and UM on RTM. Therefore, MBS on RTM by MBD can be effective to evaluate the designs against requirements.
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Produce product sample on RTM. A product sample can be produced on RTM by replacing the device model and UM with actual subsystems with hardware.
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Certify the product sample on RTM. The product sample can be physically certified safely by test participants on RTM.
Object robot and function
Methods
Plan the human-centred design process
Understand and specify the context of use by Persona
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Have you experienced any collisions or felt a collision hazard with other people during walking?
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Have you experienced any collision or hazard with attentive people, inattentive people or both?
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What were the inattentive people doing at the experience of the collision or hazard? Operating a mobile phone or others? If others, please describe what they were doing.
Experience of collision/collision hazard with | Ratio (%) |
---|---|
People not paying attention to surroundings | 100 |
People operating mobile phone | 70 |
People looking the other way | 50 |
People paying attention to surroundings | 30 |
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Did the people approached at a constant velocity or by a deceleration, at the collision or the collision hazard?
Approach pattern with fear of collision | Ratio (%) |
---|---|
Approach at constant velocity | 90 |
Approach by deceleration | 20 |
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Target is standing sometimes attentive to its surroundings, sometimes inattentive, when Robot approaches.
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Target is inattentive during the mobile phone operation.
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Target feels fear of collision, if Robot approaches at constant velocity and stops suddenly.
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Target feels a fear of collision, if Robot approaches very close to Target.
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Target becomes attentive by being warned.
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Target feels a fear of collision, if Robot moves faster than Target.
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Inattentive Target may start walking suddenly.
Specify the user requirements by MBSE
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The approach function has to warn an inattentive Target of Robot’s approach at an appropriate distance and to warn Target who may be starting to walk suddenly, for ensuring psychological security.
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The approach function has to stop Robot at an appropriate distance to avoid a collision, for ensuring physical safety.
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The approach function has to start deceleration at an appropriate distance so as not to induce any fear of collision in Target, for ensuring psychological security.
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Robot moves slower than Target.
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An appropriate distance to Target at which to stop
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An appropriate distance to Target to start deceleration
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An appropriate distance to Target to give a warning
Personal space for talking (mm) | |
---|---|
Average | 700 |
Max | 900 |
Min | 350 |
Distance to obstacle to start deceleration (mm) | |
---|---|
Average | 1600 |
Max | 3900 |
Min | 920 |
Reflex time (s) | |
---|---|
Average | 1.1 |
Max | 1.4 |
Min | 0.86 |
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H h (%): Horizontal position of hand.$$ H_{h} = \frac{{Ha_{h} - He_{h} }}{{S_{h} - He_{h} }}*100 $$(1)
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H v (%): Vertical position of hand.$$ H_{v} = \frac{{Ha_{v} - E_{v} }}{{S_{v} - E_{v} }}*100 $$(2)
H
h
< (%) |
H
v
> (%) | Sometimes distinguished (%) | Minimum recognition rate (%) | Always distinguished (%) |
---|---|---|---|---|
50 | 30 | 93 | 0 | 21 |
60 | 30 | 100 | 8 | 36 |
70 | 30 | 100 | 45 | 57 |
80 | 30 | 100 | 48 | 77 |
80 | 35 | 100 | 53 | 79 |
90 | 40 | 100 | 55 | 79 |
100 | 45 | 100 | 55 | 85 |
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A hand locates close to the center of the body in the horizontal axis.
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A hand locates higher than elbow in the vertical axis.
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All test participants sometimes satisfies the combination of H h and H v .
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The minimum recognition rate of the combination of H v and H v in all test participants is over 50 %.
Produce design solutions to meet user requirements for MBS on RTM
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Commander subsystem specifies movements of Robot, by a velocity.
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Kinect subsystem analyzes the pose of Target, and then outputs the attentiveness of Target as the result of analysis.
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LRF subsystem analyzes the distance to Target, and then outputs the size of Target, the relative position to Target, and the relative velocity to Target as the results of analysis.
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Master controller evaluates information from Commander subsystem, Kinect subsystem and LRF subsystem, and then outputs an appropriate velocity and an appropriate warning level as results of approach function. And, Master controller also has an ability to visualize movements and positions of Robot and Target, and key values for monitoring a simulation status and an experiment status.
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Warning for Target subsystem warns Target with the warning level specified by input.
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Motor drive subsystem moves Robot with the velocity specified by input.
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Target is monitored by Kinect subsystem and LRF subsystem, and is warned by Warning for Target subsystem. And Target monitors a distance to Robot, and then recognizes a velocity of Robot.
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Motor drive model subsystem consists of SEvMotorDrive_Model0.
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Warning for Target subsystem consists of SEvSound_Unit_4_Target0.
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Master controller consists of SE_Master_Controller0.
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Commander subsystem consists of SEvCommander0.
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UM of Target with sensor subsystems consists of SEvTarget_Model0.
Evaluate the designs against requirements by MBS on RTM
Produce product sample on RTM
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External dimensions: Width 455 mm / Depth 455 mm / Height 1200 mm.Maximum velocity: 500 mm/s. (By pre-experiment)
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Operation range: 0.8–3.5 m.Field of view: Horizontally 58° / Vertically 45° / Diagonally 70°.
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Maximum measuring distance and angle: 5600 mm / 240°.
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LRF subsystem consists of SEvLRF_Monitor0 and LRFCapture_URG0 (from the National Institute of Advanced Industrial Science and Technology).
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Kinect subsystem consists of SEvKINECT_Monitor0 and RT_Kinect_UserTracking0 (from the National Institute of Advanced Industrial Science and Technology).
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Motor drive subsystem consists of TRobotRTC0 (from the Tokyo Metropolitan Industrial Technology Research Institute).
Certify the product sample on RTM
Results
Results of evaluation by MBS
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Cv x specified (t n ) [mm/s]: 470. 470 mm/s is the velocity specified at evaluation and certification.
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Tv x absolute (t n ) [mm/s]: 0. 0 mm/s means that UM of Target is standing.
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TD x personal space [mm]: 700. 700 mm is the average distance of the result of the survey on personal space for talking shown in Table 3 as the appropriate distance to stop for UM of Target.
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TD x slowdown [mm]: 700/1600. We studied the differences in the sense of psychological security between the sudden stop and the decelerated stop. 700 mm was the value for the experiment of sudden stop around the border of personal space, and 1600 mm was the average value of distance to start deceleration shown in Table 4 as the appropriate distance to start deceleration for UM of Target. 1600 mm was the average distance to start deceleration at the average velocity of 860 mm/s. We assumed that this average distance could be applied also at the velocity of 470 mm/s because we assumed that the distance for deceleration from 470 mm/s would be shorter than the distance for deceleration from 860 mm/s.
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TAt (t n ) [s]: 0.0/1.4. We studied the differences in psychological security between attentive Target and inattentive Target. 0.0 s was the reflex time of attentive Target, and 1.4 s was the worst reflex time of inattentive Target in Table 5 for UM of Target.
TAt
|
TD
x
personal space
(mm) |
TD
x
slowdown
(mm) |
D
x
notify
(mm) |
TD
x
relative
at warned (mm) |
TD
x
relative
at stop (mm) |
---|---|---|---|---|---|
0.0 | 700 | 700 | 700 | 675 | 675 |
1.4 | 700 | 700 | 1358 | 1276 | 697 |
0.0 | 700 | 1600 | 1600 | 1599 | 700 |
1.4 | 700 | 1600 | 2258 | 2203 | 700 |
TAt
|
TD
x
personal space
(mm) |
TD
x
slowdown
(mm) |
PHS
at stop
|
PSS
at warned
|
---|---|---|---|---|
0.0 | 700 | 700 | 0.96 | 0.42 |
1.4 | 700 | 700 | 1.00 | 0.57 |
0.0 | 700 | 1600 | 1.00 | 1.00 |
1.4 | 700 | 1600 | 1.00 | 0.98 |
Results of certification of product sample
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Cv x specified (t n ) [mm/s]: 470
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Tv x absolute (t n ) [mm/s]: 0 (Test participant was standing.)
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TD x personal space [mm]: 700
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TD x slowdown [mm]: 700/1600
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TAt (t n ) [s]: 0.0/1.4
TAt
|
TD
x
personal space
(mm) |
TD
x
slowdown
(mm) |
D
x
notify
(mm) |
TD
x
relative
at warned (mm) |
TD
x
relative
at stop (mm) |
---|---|---|---|---|---|
0.0 | 700 | 700 | 700 | 657 | 657 |
1.4 | 700 | 700 | 1358 | 1332 | 689 |
0.0 | 700 | 1600 | 1600 | 1590 | 628 |
1.4 | 700 | 1600 | 2258 | 2237 | 700 |
TAt
|
TD
x
personal space
(mm) |
TD
x
slowdown
(mm) |
PHS
at stop
|
PSS
at warned
|
---|---|---|---|---|
0.0 | 700 | 700 | 0.94 | 0.41 |
1.4 | 700 | 700 | 0.98 | 0.59 |
0.0 | 700 | 1600 | 0.90 | 0.99 |
1.4 | 700 | 1600 | 1.00 | 0.99 |
TAt
|
TD
x
slowdown
(mm) | Psychological security (1worst–5best) | Sense of time till stop (1long–3appropriate–5short) | ||||
---|---|---|---|---|---|---|---|
Average | Max | Min | Average | Max | Min | ||
0.0 | 700 | 1.5 | 2 | 1 | 3.75 | 5 | 3 |
1.4 | 700 | 2.25 | 4 | 1 | 4 | 5 | 3 |
0.0 | 1600 | 4.75 | 5 | 4 | 2.5 | 3 | 2 |
1.4 | 1600 | 4.75 | 5 | 4 | 2.5 | 3 | 2 |
Discussion
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By the ability for Robot to stop automatically at the border of personal space, we could reduce the risk for Robot to collide with Target; thereby, the physical safety was guaranteed.
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By the ability for Robot to decelerate to a stop at the appropriate distance, both the attentive Target and the inattentive Target felt that the time till stop was appropriate and the psychological security was very good. On the other hand, both the attentive Target and the inattentive Target felt that the time till stop was too short and the psychological security was very bad, against the sudden stop.
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By the ability for Robot to warn Target at the appropriate distance that was adjusted by adding a distance related to a reflection time based on the attentiveness of Target, the inattentive Target could notice Robot approaching and became attentive. Therefore, in the case of the decelerated stop approach, the inattentive Target felt the same psychological security as the attentive Target felt. And even in the case of the sudden stop approach, Target felt a little better psychological security.
Conclusions
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To reduce time and cost required to produce the hardware of the product sample at evaluation.
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To evaluate the product by simulation, under various conditions and also repeatedly under the same condition.
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To eliminate risks injuring test participants in the evaluation, and to reduce the risks in the certification.