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Control Problems in Robotics and Automation - B. Siciliano and K.P. Valavanis (Eds) Part 2

Tham khảo tài liệu 'control problems in robotics and automation - b. siciliano and k.p. valavanis (eds) part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 6 J. De Schutter et al. implementations are very similar. However the advantage of the inner outer implementation is that the bandwidth of the inner motion control loop can be made faster than the bandwidth of the outer force control loop.4 Hence if the inner and outer loops are tuned consecutively force disturbances are rejected more efficiently in the inner outer implementation.5 Since errors in the dynamic model can be modeled as force disturbances this explains why the inner outer implementation is more robust with respect to errors in the robot dynamic model or even absence of such model . As for Impedance control the relationship between motion and force can be imposed in two ways either as an impedance or as an admittance. In impedance Control the robot reacts to deviations from its planned position and velocity trajectory by generating forces. Special cases are a stiffness or damping controller. In essence they consist of a PD position controller with position and velocity feedback gains adjusted in order to obtain the desired compliance.6 No force sensor is needed. In admittance control the measured contact force is used to modify the robot trajectory. This trajectory can be imposed as a desired acceleration or a desired velocity which is executed by a motion controller which may involve a dynamic model of the robot. 2.4 Properties and Performance of Force Control Properties of force control have been analysed in a systematic way in 7 for the Hybrid control approach and in 1 for the Impedance control approach. The statements presented below are inspired by a detailed study and comparison of both papers and by our long experimental experience. Due to space limitations detailed discussions are omitted. Statement 2.1. An equivalence exists between pure force control as applied in Hybrid control and Impedance control. Both types of controllers can be converted to each other. Statement 2.2. All force control implementations when optimized are expected to have .