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Impedance Control of Flexible Base Moving Manipulators

Salehi, Mahdi | 2009

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 39620 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Vossoughi, Gholamreza
  7. Abstract:
  8. In this paper, the general research of impedance control is addressed for a robotic manipulator with a moving flexible base. Impedance control imposes a relation between force and displacement at the contact point with the environment. The concept of impedance control of flexible base moving manipulators (FBMM) is rather new and is being considered. The dynamic of manipulator is decomposed into slow and fast dynamics using singular perturbation method. New sliding mode impedance control method (SMIC), using an element on the end effector is proposed for high precision impedance control of FBMM. The sliding mode impedance control method as a robust impedance control law is derived for the slow dynamics. The asymptotic stability of the overall system is guaranteed using a combined control law comprising the impedance control law for the slow dynamics and a feedback control law for the fast dynamics. Active controller on the end effector (ACEE) is able to eliminate the force chatter at the contact. This proposed sliding mode impedance controller with active end effector control was simulated for two models. First model is a simple FBMM composed of a 2 DOFs planar manipulator and a single DOF moving base with flexibility in between. Second model is an advanced 10 DOF FBMM composed of a 4 DOF manipulator and a 6 DOF moving base with flexibility. This controller provides desired position/force control accurately with satisfactory damped vibration at both soft and hard contact. Control element on the end effector was able to eliminate chattering of position and force about their desired values. SMIC/ACEE represents a new framework for high precision impedance control of moving and/or flexible base robotic manipulators. Also , SMIC/ACEE as the sliding mode impedance controller with active end effector control was simulated for two models. Proposed controller provides desired position/orientation of the end effector and contact force accurately with satisfactory damped vibration at the both soft and hard contact moments. Control element on the end effector was able to eliminate chattering of position and force about their desired values. Other proposed method in the project is using online PSO (Particle Swarm Optimization method) for elimating chattering and adapting to unknown environments with previous proposed sliding mode impedance controller. This proposed control method SMIC/PSO was simulated for a simple model of FBMM. Desired parameters were provided without chattering effect and all impedance control coefficients were tuned and converged by proposed online PSO algorithm after minimum contact moments.


  9. Keywords:
  10. Impedance Control ; Mobile Manipulator ; Sliding Mode Control ; Flexibility ; Singular Perturbation

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