Position and force control of a vehicle with two or more steerable drive wheels

Technical Report · Thu Oct 01 00:00:00 EDT 1992

DOI:https://doi.org/10.2172/10151323· OSTI ID:10151323

Reister, D B; Unseren, M A

When a vehicle with two or more steerable drive wheels is traveling in a circle, the motion of the wheels is constrained. The wheel translational velocity divided by the radius to the center of rotation must be the same for all wheels. When the drive wheels are controlled independently using position control, the motion of the wheels may violate the constraints and the wheels may slip. Consequently, substantial errors can occur in the orientation of the vehicle. A vehicle with N drive wheels has (N - 1) constraints and one degree of freedom. We have developed a new approach to the control of a vehicle with N steerable drive wheels. The novel aspect of our approach is the use of force control. To control the vehicle, we have one degree of freedom for the position on the circle and (N - 1) forces that can be used to reduce errors. Recently, Kankaanranta and Koivo developed a control architecture that allows the force and position degrees of freedom to be decoupled. In the work of Kankaanranta and Koivo the force is an exogenous input. We have made the force endogenous by defining the force in terms of the errors in satisfying the rigid body kinematic constraints. We have applied the control architecture to the HERMIES-III robot and have measured a dramatic reduction in error (more than a factor of 20) compared to motions without force control.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 10151323
• Report Number(s): ORNL/TM-12193; ON: DE93012512; TRN: TRN: 93:001110
• Resource Relation: Other Information: PBD: Oct 1992
• Country of Publication: United States
• Language: English

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33 ADVANCED PROPULSION SYSTEMS
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DEGREES OF FREEDOM
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