Unidrive Modular Robot: Dynamics, Control, and Experiments

[+] Author and Article Information
Hamidreza Karbasi, Amir Khajepour, Jan Paul Huissoon

Department of Mechanical Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada

In a SWC as the torsional spring wraps down, the output torque increases linearly in a short period of time and the output velocity becomes equal to the input velocity rapidly. To model this, it is assumed that a virtual viscous friction is acting between the input and output shafts (for details see Ref. 6).

J. Dyn. Sys., Meas., Control 128(4), 969-975 (Nov 15, 2005) (7 pages) doi:10.1115/1.2363199 History: Received October 18, 2004; Revised November 15, 2005

In this paper, a control design methodology for the new class of modular robots so-called “unidrive modular robots” is introduced. Unidrive modular robots because of employing only a single drive for operating all the joints have a substantial advantage over regular modular robots in terms of the mass of each module. The drive is mounted at the robot base and all joints tap power from the single drive using clutches. By controlling the engagement time of the clutches, the position and velocity of the joints are regulated. In this work, a general state space model of the robot is first developed and then based on the theory of variable structure systems and sliding mode control a design methodology for local controllers is introduced. The control design technique is validated by experimental results.

Copyright © 2006 by American Society of Mechanical Engineers
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Figure 3

Schematic of the unidrive modular robot control system

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Figure 4

Schematic of the mechanical drive

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Figure 5

Proposed lumped model for SWCs

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Figure 1

Series configuration of the unidrive modular robot

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Figure 2

Parallel configuration of the unidrive modular robot

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Figure 6

Nonlinear PWM controlled system

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Figure 7

Average model of ON-OFF-ON PWM controlled system

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Figure 8

Unidrive gantry robot

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Figure 9

PWM signals with different frequencies: (a) 5Hz, (b) 20Hz

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Figure 10

Chattering reduced by increasing PWM frequency

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Figure 11

Effects of different gains on 20Hz PWM: (a) gain=0.05, (b) gain=0.1, (c) gain=0.2

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Figure 12

Steady state error reduction in the controlled response due to gain increasing




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