GPS and GIS in supply chain

Summary

The lecture explains how GPS and GIS extend supply-chain visibility beyond the range of RFID, then shows how location and demand data can support vehicle routing—especially when requests change in real time.

1. Tracking Goods Beyond RFID Range

• RFID can identify or track goods while they are within an RFID reader’s coverage, such as at a manufacturer, warehouse, or retailer.
• Once a shipment leaves that coverage and enters a transport network, RFID alone cannot track its progress.
• GPS can track the vehicle carrying the goods while it is on the road or elsewhere in transit.

2. How GPS Works

GPS is described as a space-based radio-navigation system owned by the U.S. government and operated by the U.S. Air Force. It can determine a receiver’s position without telephone or internet connections.

The lecture describes three main GPS components:

• Space segment: Satellites orbiting Earth and broadcasting signals.
• User segment: Receivers such as phones or vehicle GPS devices.
• Control segment: Ground stations that monitor satellite operation and send updates and commands.

A GPS receiver records the arrival time of satellite signals and uses their timing and the satellites’ known positions to estimate its distance from them. Using satellite measurements:

• Signals from three satellites can establish a two-dimensional position.
• Signals from four satellites can establish a three-dimensional position, including altitude.

The lecture also notes that other countries or regions have developed or pursued comparable satellite-navigation systems.

3. Turning GPS Location into Operational Tracking

GPS can tell a device its own location, but a logistics operator needs that location to reach a server so the company can monitor vehicles and send instructions.

A typical vehicle-tracking process is:

1. Install a GPS module in the vehicle.
2. Have the module determine the vehicle’s position.
3. Transmit the location through a mobile network to the company’s server.
4. Use software and decision-support tools to assess the vehicle’s position and operational needs.
5. Send instructions back over the mobile network.
6. Present the instructions to the driver through an in-vehicle interface.

GPS provides location, while GIS helps organize, display, analyze, and use geographic information for decisions.

4. GIS and Integrated GPS–GIS Systems

A Geographic Information System (GIS) is software for inputting, storing, manipulating, displaying, and outputting geographic or spatial information. GIS can combine spatial data with related attribute and enterprise data—for example, transport or fleet information—to support planning and management.

The lecture describes GIS data as layered and mentions TIGER files as a format for encoded geographic information. Systems that use GPS to collect spatial data for a GIS are called integrated GPS–GIS systems.

In a supply chain, these systems can track vehicles and cargo outside RFID coverage. GIS can store incoming data, answer user queries, generate reports, and support data transformation and analysis. The lecture mentions applications in automotive operations, airlines, agriculture, sports, and law enforcement.

5. Vehicle Routing Problems

A vehicle routing problem (VRP) asks how to serve a group of customers from a depot using a fleet of vehicles while minimizing transportation costs.

The problem has two linked parts:

• Customer grouping: Cluster customers so nearby customers can be served together.
• Route planning: Determine the best sequence of stops for each vehicle within its assigned group.

The lecture distinguishes a route—the deliveries made by a vehicle—from a tour—the sequence in which those stops are visited. Routes generally start and end at the depot.

Possible VRP variations include:

• Limits on vehicle capacity or the kinds of goods carried.
• Customer time windows for pickup or delivery.
• Multiple depots or vehicle fleets.
• Service over several days.
• Splitting an order among multiple vehicles.
• Uncertain or probabilistic elements.
• Satellite facilities or real-time monitoring of the transport network.

6. Static and Dynamic Routing

• A static routing problem assumes all important planning information is known in advance and remains unchanged after routes are built.
• A dynamic routing problem involves information that is initially unknown or changes after the initial routes are planned—for example, a new urgent customer request.
• Dynamic problems are harder because routes may need to be updated while vehicles are already operating.
• VRPs are combinatorial and NP-hard. As the number of customers and vehicles grows, finding an optimal solution can become very time-consuming.
• For real-time operations, the goal may therefore be to find a good, workable solution quickly rather than a provably optimal one.

7. Examples of Dynamic Routing

The lecture gives several examples where vehicles may need to be redirected in response to changing needs:

• Dynamic fleet management: Dispatching vehicles for freight pickup or delivery.
• Supplier-driven distribution: A supplier monitoring customer inventory may need to send a truck to a retailer facing an unexpected stock shortage.
• Courier services: Handling same-day local pickup and delivery requests, including shipments that connect to remote terminals.
• Rescue and repair services: Dispatching help for breakdowns or other urgent service requests.
• Taxi services: Matching new ride requests with nearby vehicles.
• Emergency services: Dispatching police, fire, or ambulance vehicles.

8. Data and Decision-Support Workflow

The lecture identifies two main data inputs for routing decisions:

• Location data, supplied by GPS and communicated through an integrated GPS/GPRS and mobile-network setup.
• Demand data, supplied by corporate systems, potentially connected through EDI or web services.

A typical decision process is:

1. Collect vehicle location and customer demand data.
2. Feed both into a transport management or decision-support system.
3. Use routing algorithms and GIS to evaluate possible actions.
4. Display the results to a decision-maker.
5. Adjust the proposed solution manually if needed, since complex algorithms may not capture every practical constraint.
6. Send the final instructions to the vehicle over the mobile network.

Speakers and Sources Featured

• Speaker: One lecturer or presenter, unnamed in the subtitles.
• Systems and information sources discussed: GPS satellites; the GPS ground control segment; vehicle or phone GPS receivers; mobile networks; GIS and integrated GPS–GIS systems; and corporate demand-data systems connected through EDI or web services.
• Organizations or regional systems mentioned: The U.S. government and U.S. Air Force in connection with GPS; the European Union and India in connection with comparable or developing navigation systems.