Effect of Stabilization Control for Cooperation between Tele-Robot Systems

with Force Feedback by Using Master-Slave Relation

Kazuya K𝐚𝐚𝐚𝐚𝐚𝐚𝐚𝐚𝐚𝐚𝐚𝐚𝐚𝐚†, Yutaka Ishibashi†, Pingguo Hung‡, and Yuichiro Tateiwa†

† Nagoya Institute of Technology, ‡Seijoh University

2020 IEEE Conference on Computer Applications (ICCA)February 27 - 28, 2020, Novotel Hotel, Yangon, Myanmar

Outline Background Problems Purpose Tele-robot systems with force feedback Adaptive Δ-causality control Stabilization control Experiment method Experiment results Conclusion and Future work

Background Remote robot systems with force feedback have actively been

researched. It is possible to transmit the information about the shape,

weight, and softness of a remote object by using haptic interface devices.

The efficiency and accuracy of work can largely be improved by using the remote robot system with force feedback.

However, when we transmit haptic information over the

Internet, which does not guarantee QoS (Quality of

Service)

Network delay, delay jitter, and

packet loss・QoE (Quality of Experience) degrades・Instability phenomena occur.

QoS control and stabilization control

Previous work *1 Applied the adaptive Δ-causality control to the cooperative work of

the two tele-robot systems with force feedback by using master-slave relation .

Investigated the effect of the adaptive ∆-causality control by experiment.

The influence of network delay can greatly be alleviated by the control

The reaction force is set to a value by multiplying 0.5 to the force detected by the robot's force sensor.

We can use the stabilization control with filters.The effect of the stabilization control has not been clarified quantitatively in the systems using the master-slave relation.

Problems*1 K. Kanaishi, et al., in Proc. ICTCE, Nov. 2019.

Purpose

We perform the stabilization control with filters for the tele-robot systems using the master-slave relation with force feedback in which the adaptive ∆-causality control is exerted.

Clarify the effect of the stabilization control.

Investigate the effect of the adaptive ∆-causality control under the stabilization control.

This work

Remote robot systems with force feedback

Carrying Object TogetherMove a wooden stick together by the two industrial robot arms

while watching video. In order to move the robot arms in almost the same way always,

we push and drop the uppermost block of the piled building blocks by moving the robot arms together with the force feedback devices.Toggle clamp handof slave robot arm Wooden stick

Toggle clamp handof master robot arm

Building blocks

Calculation method of position

Position of robot

𝑺𝑺𝑡𝑡 = �𝑴𝑴𝑡𝑡−1 + 𝑽𝑽𝑡𝑡−1 ( 𝑽𝑽𝑡𝑡−1 ≤ 𝑉𝑉max)

𝑴𝑴𝑡𝑡−1 + 𝑉𝑉max𝑽𝑽𝑡𝑡−1𝑽𝑽𝑡𝑡−1

(otherwise)

𝑺𝑺𝒕𝒕 : Position vector of industrial robot at time 𝒕𝒕( 𝒕𝒕 > 𝟏𝟏)𝑴𝑴𝒕𝒕: Position vector of haptic interface device at time 𝒕𝒕𝑽𝑽𝒕𝒕 : Velocity vector of industrial robot𝑽𝑽𝐦𝐦𝐚𝐚𝐦𝐦 : Maximum velocity of industrial robot (5mm / ms)

Calculation method of force

Force outputted at master terminal

𝑭𝑭𝑡𝑡(m) = 𝐾𝐾scale𝑭𝑭𝑡𝑡−1

(s)

𝑭𝑭𝒕𝒕(𝐦𝐦) : Reaction force outputted at the master terminal at time

𝑡𝑡(>0)

𝑭𝑭𝒕𝒕(𝐚𝐚) : Force received at the master terminal from the slave

terminal at time 𝑡𝑡 (> 0)

𝑲𝑲𝐚𝐚𝐬𝐬𝐚𝐚𝐬𝐬𝐬𝐬 : Force scale which changes 𝑭𝑭𝒕𝒕−𝟏𝟏(𝐚𝐚)

𝑲𝑲𝐚𝐚𝐬𝐬𝐚𝐚𝐬𝐬𝐬𝐬 = 𝟏𝟏.𝟎𝟎

Demo video (Carrying object together)

Slave robot Master robot

Master - slave relation

Output positioninformation

Follow master robot.

Output positioninformation

Robot arm’s motion is delayed.

Send position information

Large network delay

Large force may be applied to an object.

Send position information

Network delay : Δ ms

Wait for Δ ms without outputOutput position information

Output positioninformation

Robot arm’s motion is not

delayed.

Adaptive Δ-causality control (1/2)

No large force may be applied to an object.

Δ is set to the smoothed network delay 𝑫𝑫𝒕𝒕.

�𝑫𝑫𝟎𝟎 = 𝒅𝒅𝟎𝟎𝑫𝑫𝒕𝒕 = 𝜶𝜶𝑫𝑫𝒕𝒕−𝟏𝟏 + 𝟏𝟏 − 𝜶𝜶 𝒅𝒅𝒕𝒕 (𝒕𝒕 ≥ 𝟏𝟏)

Smoothing coefficient 𝜶𝜶 = 𝟎𝟎.𝟗𝟗𝟗𝟗𝟗𝟗*2

𝒅𝒅𝒕𝒕 : Network delay at time t

Information received after generation time + Δ is discarded as old and useless information.

Adaptive Δ-causality control (2/2)*2 T. Abe et al., Journal of IEICE, vol. 91, no. 2, Feb. 2008.

Stabilization control with filters

The stabilization control with filters uses the wave filter in combination with the phase control filter.

The control can make the remote robot system with force feedback stable against any network delay*3.

*3 P. Huang et al., IEICE, CQ2017-79, Nov. 2017.

Experiment method

We generated a constant delay (called the additional delay) for each packet transmitted between the two systems by a network emulator (NIST Net).

We measured the force sensed by the force sensor and the robot arm position .

Experiment results (1/2)

No stabilization control Stabilization control

Additional delay : 200 ms

Position and Force in the x-axis of each robot under QoS control

Posi

tion

[mm

]

Posi

tion

[mm

]

Forc

e [N

]

Forc

e [N

]

Elapsed time [sec.] Elapsed time [sec.]

Elapsed time [sec.] Elapsed time [sec.]

Master robotSlave robot

Master robot

Master robot

Slave robot

Slave robot

Slave robot

Master robot

Experiment results (2/2)Position and Force in the x-axis of each robot under stabilization control

No QoS control QoS control

Additional delay : 200 ms

Posi

tion

[mm

]

Posi

tion

[mm

]

Forc

e [N

]

Forc

e [N

]

Elapsed time [sec.] Elapsed time [sec.]

Elapsed time [sec.] Elapsed time [sec.]

Master robot

Master robot

Master robot

Master robotSlave robot

Slave robot Slave robot

Slave robot

Conclusion

The instability phenomena can greatly be suppressed by the stabilization control in the systems.

The adaptive ∆-causality control is effective under the stabilization control.

We applied the stabilization control with filters and the adaptive ∆-causality control for cooperative work between the tele-robot systems with force feedback by using a master-slave relation.

We investigated the effects of the stabilization control and the adaptive ∆-causality control.

Future work

Apply the stabilization control with filters and the adaptive ∆-causality control to the systems with an equal relationship and investigate their effects.

Switch the master-slave relationship dynamically according to the network delay in the systems.

Effect of Stabilization Control for Cooperation between Tele-Robot Systems with Force Feedback �by Using Master-Slave RelationOutlineBackgroundProblemsPurposeRemote robot systems with force feedbackCarrying Object TogetherCalculation method of position Calculation method of forceDemo video (Carrying object together)Master - slave relationスライド番号 12スライド番号 13Stabilization control with filtersExperiment method Experiment results (1/2)Experiment results (2/2)ConclusionFuture workスライド番号 20Experiment results