The mini-project: from requirement to defended design
The capstone methodology (specification, control philosophy, sizing, simulation, defence), the three project workshops, the marking rubric, suggested themes, and the mistakes the rubric punishes.
25 min
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The mini-project is the synthesis of the course. Working in small groups, you choose a complex industrial mechanism and develop a complete control strategy for it, showing that you can integrate selection, control and automation. It reverses the direction of study: instead of analysing a given mechanism, you conceive one. This lesson is course section 6.3 with the Chapter 6 tutorials, and Lab VI is its simulation part.
The method
The project follows a disciplined engineering-design sequence that mirrors professional practice (course fig. 6.6):
- Problem definition and specification. Define the mechanism and write its technical specification: the required motions, the load characteristics of each, the duty cycle, the performance targets (speed range, positioning accuracy, cycle time), and the environmental and safety constraints. A well-written specification is the contract against which the design is later validated.
- Control philosophy. The overall strategy: each controlled axis, its load classification and hence its drive type, the sensors and feedback, the interlocks and safety functions, the operator interface, and the coordination between axes. It is expressed in block diagrams and sequence descriptions, not yet in wiring.
- Component selection and sizing. Motors sized from the load and duty analysis of Chapter 1; drives chosen for the quadrants and control quality needed; braking equipment, protection, and the controller. Every selection is justified by calculation and referred to manufacturer data, as in the tutorials of Chapters 1 to 5.
- Simulation and analysis. Where possible, the design is validated by simulation (the drive response, the control loops or the sequence logic) before it is presented. This is Lab VI.
- Presentation and defence. The group presents its solution and answers technical questions.
Three workshop weeks
The Chapter 6 tutorials are not problem classes but supervised project workshops over three weeks:
- Week 1, proposal. Form groups, choose a mechanism (from the case studies of this chapter or your own), and draft the specification and control philosophy for approval.
- Week 2, development. Supervised work on sizing and control design, with the same methods as the tutorials of Chapters 1 to 5.
- Week 3, presentation and defence. Each group presents and defends its complete control strategy.
There are no worked exercises or model answers for this chapter: the solution is the design each group develops and defends.
Suggested themes
The Lab Works booklet suggests five themes, each tied to an earlier lab:
| Mechanism | Simulation focus |
|---|---|
| Reversing rolling mill | four-quadrant speed reversal with inter-stand tension control |
| Cement kiln drive | constant-torque low-speed drive with auxiliary (inching) failover |
| Drilling draw-works | four-quadrant hoist with regenerative lowering (Labs III, IV) |
| Web tension control (winder) | constant-power torque and speed coordination as the roll radius changes |
| Bucket-wheel excavator | coordinated cutting, slewing and conveyor flow matching (Lab V) |
How it is marked
The mini-project is the main continuous-assessment instrument for UEF 2.1.2, marked out of 20 on five criteria (course overview, table 4):
| Criterion | What is assessed | Marks |
|---|---|---|
| Specification | completeness and realism: motions, loads, duty cycle, targets, environmental and safety constraints | 4 |
| Control philosophy | load classification per axis; drive type and control mode; sensors, interlocks, operator interface, coordination between axes | 4 |
| Component sizing | correctness and justification of every calculation; manufacturer data; adequate torque, power and duty margins | 5 |
| Safety and reliability | fail-safe braking, safety chains, redundancy and the relevant standards | 3 |
| Presentation and defence | clear diagrams and argument; quality of the simulation evidence; answers to technical questions | 4 |
Indicative bands: 16–20, a professional-quality design with every selection justified and validated; 12–15, sound with minor gaps in justification; 10–11, acceptable but with an unjustified selection or an untreated safety requirement; below 10, specification or sizing not defensible.
Predict first
Two groups' designs both work in simulation. One states its assumptions, justifies each component against a standard, quantifies its margins and lists its failure modes; the other only shows that it works. How does the rubric treat them?
FoundationStart here if this is new to you
A recipe that turned out well once is not yet a recipe you can hand to someone else. For that you write down the ingredients and why each is there, the quantities and the margin for error, what goes wrong if the oven runs hot, and you cook it again to check. The mini-project asks the same of a machine.
ExplorerGo deeper: derivations and open questions
Your specification. For the theme you choose, write the specification as a table of numbers with units: every motion, its load, its duty, its targets. Which entry are you least sure of, and how would you find a defensible value?
Your biggest risk. Before any simulation, name the assumption most likely to be wrong in your design. What would it change if it were?