Robust Haptic Teleoperation of a Mobile Manipulation Platform - PowerPoint PPT Presentation

Robust Haptic Teleoperation of a Mobile Manipulation Platform Jaeheung Park, Oussama Khatib System Setup Stanford AI Lab, Stanford University Control of a Mobile . . . Teleoperation Force Control Stiffness Estimation Experimental Results Conclusion Juliet Setting a Dinner . . . ISER 2004

1. System Setup System Setup Control of a Mobile . . . Teleoperation Force Control Stiffness Estimation Experimental Results Conclusion Juliet Setting a Dinner . . . • Master Haptic Device: PHANTOM 1.0 SensAble ISER 2004 • Slave Mobile Manipulator: PUMA560 on XR4000

2. Control of a Mobile Manipulator ˆ F c Force F ∗ f Control Ω f F ∗ ˆ J T Λ Σ Σ Γ F ∗ m Σ Robot Ω m System Setup Motion Control of a Mobile . . . Control µ + ˆ ˆ p Teleoperation q, f c Force Control Stiffness Estimation Γ 0 Null Space N T Experimental Results Control Conclusion Juliet Setting a Dinner . . . Control: The equations of motion for the J T F + N T Γ 0 Γ = end-effector: Λ F ∗ + ˆ ˆ p + ˆ F = µ + ˆ F c ISER 2004 Λ( q ) ˙ ϑ + µ ( q, ˙ q ) + p ( q ) + F c = F where F ∗ = Ω f F ∗ f + Ω m F ∗ m

3. Teleoperation Master Virtual Slave Environment Spring Device Robot System Setup Control of a Mobile . . . A human operator Teleoperation Force Control K vir K s Stiffness Estimation Experimental Results Conclusion Juliet Setting a Dinner . . . ISER 2004

3. Teleoperation Master Virtual Slave Environment Spring Device Robot System Setup Control of a Mobile . . . A human operator Teleoperation F d F d F c Force Control Stiffness Estimation Experimental Results Conclusion Juliet Setting a Dinner . . . ISER 2004

3. Teleoperation Master Virtual Slave Environment Spring Device Robot System Setup Control of a Mobile . . . A human operator Teleoperation F d F d F c Force Control Stiffness Estimation Experimental Results Conclusion Juliet Setting a Dinner . . . Force Control Apply F d makes F c track F d ISER 2004

3. Teleoperation Master Virtual Slave Environment Spring Device Robot System Setup Control of a Mobile . . . A human operator Teleoperation F d F d F c Force Control Stiffness Estimation Experimental Results Conclusion Juliet Setting a Dinner . . . Force Control Apply F d makes F c track F d The human operator F c ≈ F d feels F d . ISER 2004

3. Teleoperation Master Virtual Slave Environment Spring Device Robot Damping System Setup Control of a Mobile . . . A human operator Teleoperation Force Control Stiffness Estimation K vir K s Experimental Results Conclusion Juliet Setting a Dinner . . . Force Control Apply F d makes F c track F d The human operator F c ≈ F d feels F d . ISER 2004

Block Diagram - + x s x m s p Σ Slave System K vir Master Device System Setup Control of a Mobile . . . - F h F d Teleoperation Human s f Force Control Operator Stiffness Estimation Experimental Results Conclusion Juliet Setting a Dinner . . . x m , x s Master and slave position s p , s f Scaling for position and force K vir Virtual spring constant F d Desired contact force for both master and slave ISER 2004

4. Force Control With the equation of motion for each direction in the operational space coordinate, ˙ ϑ f = F ∗ f System Setup Control of a Mobile . . . Teleoperation Force Control Stiffness Estimation Experimental Results Conclusion Juliet Setting a Dinner . . . ISER 2004

4. Force Control With the equation of motion for each direction in the operational space coordinate, ˙ ϑ f = F ∗ f and a spring model System Setup ˙ Control of a Mobile . . . F c = K s ϑ f , Teleoperation Force Control Stiffness Estimation Experimental Results Conclusion Juliet Setting a Dinner . . . ISER 2004

4. Force Control With the equation of motion for each direction in the operational space coordinate, ˙ ϑ f = F ∗ f and a spring model System Setup ˙ Control of a Mobile . . . F c = K s ϑ f , Teleoperation Force Control Stiffness Estimation The system transfer function can be derived as Experimental Results Conclusion G ( s ) = K s e − sT d s ( s + K 2 ) . Juliet Setting a Dinner . . . T d system input delay K 2 additional damping ISER 2004

Block Diagram F d r k F ∗ F c G ( s ) L 1 Σ Σ - - p k ˆ System Setup Control of a Mobile . . . Observer L r ˆ x k Teleoperation Force Control Stiffness Estimation Experimental Results Conclusion F c Contact force at the end-effector Juliet Setting a Dinner . . . F d Desired contact force F ∗ Command input x k ˆ State estimate p k ˆ Input error estimate r k , L 1 Reference input, and a scaling factor L k Full state feed-back gain ISER 2004 System transfer function from F ∗ to F c G ( s )

5. Stiffness Estimation The results of force control without adaptation 10 20 Desired Contact Force 15 0 Estimated Contact Force System Setup 10 Measured Contact Force -10 Control of a Mobile . . . 5 -20 0 Teleoperation Force [N] Force [N] -30 -5 Force Control -10 -40 Stiffness Estimation -15 -50 Desired Contact Force -20 Experimental Results -60 Estimated Contact Force -25 Measured Contact force Conclusion -70 -30 137.2 137.4 137.6 137.8 138 138.2 68 69 70 71 72 73 74 75 Juliet Setting a Dinner . . . Time [sec] Time [sec] ˆ ˆ K s = 100 N/m K s = 3000 N/m K s changes from K s changes from free space to 3000 N/m . free space to 300 N/m . ISER 2004

Adaptation Law Two Ideas from experiments: ˆ s = ˆ s, 1 + ˆ K f,i K f,i K i s, 2 . 1. Under/Over-estimated K s shows Different characteristics among the desired, measured, and estimated contact force. ˆ s, 1 = ˆ s, 1 + ∆ ˆ K i K i − 1 K i s, 1 , where System Setup � c, | F m − F e | � Control of a Mobile . . . ∆ ˆ K i = k 1 | F m − F e | σ d − b 1 s, 1 Teleoperation | F e | + a 1 Force Control � c, | F d − F e | � − k 2 | F d − F e | σ d − b 2 , Stiffness Estimation | F e | + a 2 Experimental Results 1 Conclusion σ d ( c, x ) = 1 + e − cx . Juliet Setting a Dinner . . . ISER 2004

Adaptation Law Two Ideas from experiments: ˆ s = ˆ s, 1 + ˆ K f,i K f,i K i s, 2 . 1. Under/Over-estimated K s shows Different characteristics among the desired, measured, and estimated contact force. ˆ s, 1 = ˆ s, 1 + ∆ ˆ K i K i − 1 K i s, 1 , where System Setup � c, | F m − F e | � Control of a Mobile . . . ∆ ˆ K i = k 1 | F m − F e | σ d − b 1 s, 1 Teleoperation | F e | + a 1 Force Control � c, | F d − F e | � − k 2 | F d − F e | σ d − b 2 , Stiffness Estimation | F e | + a 2 Experimental Results 1 Conclusion σ d ( c, x ) = 1 + e − cx . Juliet Setting a Dinner . . . 2. System stiffness, K s , increases with the applied contact force. ˆ K s, 2 = K min + k 3 σ d ( c 0 , | F m | − F 0 ) . ISER 2004

6. Experimental Results System Setup Control of a Mobile . . . Teleoperation Force Control Stiffness Estimation Experimental Results Conclusion Juliet Setting a Dinner . . . • Position Scale from Haptic Device to PUMA : 2.0 • Force Scale from PUMA to Haptic Device : 0.1 • Time Delay in communication : about 26 ms in one direction ISER 2004

Moving base teleoperation: Base Motion Desired Position 0.2 Base position in lateral direction[m] 0.15 0.1 0.05 0 -0.05 -0.1 -0.15 System Setup -0.2 Control of a Mobile . . . 110 115 120 125 130 135 Time [sec] Teleoperation Base motion in the lateral direction(i.e. along the table) Force Control The amplitude is 20 cm and the period is 12 seconds. Stiffness Estimation Experimental Results Conclusion Juliet Setting a Dinner . . . ISER 2004

Moving base teleoperation: force response Desired Contact Force 5 Estimated Contact Force Force in vertical direction[N] 0 -5 -10 -15 -20 System Setup -25 Control of a Mobile . . . 110 115 120 125 130 135 Time [sec] Teleoperation Desired and Estimated Contact Force Force Control Stiffness Estimation Experimental Results Desired Contact Force Conclusion 5 Measured Contact Force Juliet Setting a Dinner . . . Force in vertical direction[N] 0 -5 -10 -15 -20 -25 ISER 2004 110 115 120 125 130 135 Time [sec] Desired and Measured Contact Force

Moving base teleoperation: ˆ K s and position tracking 4000 Estimated Environment Stiffness [N/m] 3500 3000 2500 2000 1500 1000 System Setup 500 Control of a Mobile . . . 0 110 115 120 125 130 135 Teleoperation Time [sec] Estimated Environment Stiffness Force Control Stiffness Estimation Experimental Results 0.92 Conclusion End-Effector Haptics Juliet Setting a Dinner . . . 0.9 Position in vertical direction[m] 0.88 0.86 0.84 0.82 0.8 ISER 2004 0.78 110 115 120 125 130 135 Time [sec] End-effector Tracking Haptic Device Position

Moving base teleoperation: force comparison 15 Desired Contact Force Applied Haptic Force 10 Force in vertical direction[N] 5 0 -5 -10 -15 -20 System Setup -25 Control of a Mobile . . . 110 115 120 125 130 135 Time [sec] Teleoperation Desired Contact Force and Applied Haptic Force to User Force Control Stiffness Estimation Experimental Results 15 Conclusion Measured Contact Force Applied Haptic Force 10 Juliet Setting a Dinner . . . Force in vertical direction[N] 5 0 -5 -10 -15 -20 ISER 2004 -25 110 115 120 125 130 135 Time [sec] Measured Contact Force and Applied Haptic Force to User