The inertial parameters of manipulator rigid-body loads and links have been automatically estimated as a result of gen eral movement. The Newton-Euler equations have been recast to relate linearly the measured joint forces or torques via acceleration-dependent coefficients to the inertial parame ters, which have then been estimated by least squares. Load estimation was implemented on a PUMA 600 robot equipped with an R TI FS-B wrist force-torque sensor and on the MIT Serial Link Direct Drive Arm equipped with a Barry Wright Company Astek wrist force-torque sensor. Good estimates were obtained for load mass and center of mass, and the forces and torques due to movement of the load could be pre dicted accurately. The load moments of inertia were more difficult to estimate. Link estimation was implemented on the MIT Serial Link Direct Drive Arm. A good match was ob tained between joint torques predicted from the estimated parameters and the joint torques estimated from motor cur rents. The match actually proved superior to predicted torques based on link inertial parameters derived by CAD modeling. Restrictions on the identifiability of link inertial parameters due to restricted sensing and movement near the base have been addressed. Implications of estimation accu racy for manipulator dynamics and control have been consid ered.
Simple auctions neglect the complex business constraints required by strategic sourcing. The Mars-IBM team created a procurement auction Web site 〈www.number1traders.com〉 that enables buyers to incorporate complex bid structures (such as bundled all-or-nothing bids and quantity-discounted bids) and business constraints into strategic-sourcing auctions. Outcomes in such auctions must lead to win-win solutions to sustain long-term relationships between procurer and suppliers. These factors are as important or more important than price. The Mars procurement auction Web site supports several alternatives to simple auctions that help match its needs as procurer and the capabilities of suppliers by incorporating optimal bid selection subject to constraints based on business rules in a dynamic environment. The ability to consider geographic, volume, and quality factors helps both parties. Feedback from participant suppliers has highlighted the benefits of time efficiency, transparency, and fairness. Although they reflect just one side of the benefits ledger, the monetary benefits to Mars (a $14 billion company) and to its suppliers are significant.
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