Concept development of steering
column
Accommodating business commuters in a level four autonomous car
Konceptframtagning av styrkolonn
En styrkolonn anpassad för pendlare i en klass fyra autonom bil
Victor Wetterlind
Faculty of Health, Science and Technology
Degree Project for Bachelor of Science in Innovation and Design Engineering 22.5 ECTS
9 opposition (critical peer-review) has to be done. The project leader is expected to deliver a technical solution for his chosen concept and if time allows also produce a functioning prototype to validate function. The result is to be delivered the 18 of June 2018. The individual goal for the author if this thesis is to fulfil the criteria’s listed in Course PM (se appendix 1) in order to achieve a pass in the course and collect a bachelors’ thesis diploma.
1.6 Project structure
The design product development methodology used for this project is from Produktutveckling (Johannesson, et al., 2013) and follows figure 1. It is an iterative process since information and knowledge broadens along the project. Figure 1. The process for reaching the project goal according to Produktutveckling (Johannesson, et al., 2013), it is an itterativ process. This process is a common way to solve product development projects. In his book Mechanical Design Engineering Handbook, Childs (2014) recommends a similar approach, he does not however think it is as iterative as Johannesson, et al. (2013) does, see figure 2. Having a clear and structured way of working is essential and have many benefits (Rowe, 2015). Figure 2, the process of product development according to Mechanical design engineering handbook (Childs, 2014). Both Childs (2014) and Johannesson, et al. (2013) start with researching the demand followed by the creation of a product specification. This specification contains all the necessary information about the finished product, what it should be able to do and optional features which will add value to the finished product. This specification is then used as a reference when comparing concepts and for evaluation of how well the finished product reaches its purpose. During the conceptual design, solutions that fulfill the product specification is created by concept generation methods. The Feasibilitystudy specificationProduct generationConcept evaluation Concept constructionLayout constructionDetail
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2.4 Product specification
The product specification was created systematically with the help of an Olsson matrix (see Table 1) which is an excellent tool of getting various aspects into a product specification (Johannesson, et al., 2013). The table is modified to suit the application better. In the original table, there are five life cycle phases. Since this is a product that is a part of a larger and more complex system a life cycle phase which contains selling, distribution etc. is not considered. Table 1. Lifecycles and influencing aspects of products according to Olsson (Johannesson, et al., 2013). Lifecycle phase Aspect16 Table 2. The design core: aspects that should go into a design specification according to Pugh, this to cover as many aspects as possible and reach a complete design specification as quickly as possible (Childs, 2014). The design core
Quality Competition Maintenance Weight Market
constraints
Politics Manufacturing
facility Disposal Company constraints Packaging Shipping Size Processes Customer Timescales Product cost Performance Life in
service Installation Aesthetics Standard
specifications
Ergonomics Materials Product lifespan
Quantity Documentation Company
liability Legal Safety Testing
Packing Environment Patents Storage Shell life Reliability
20 In the original method six people are attend an idea generation session. To start with they create three concepts each. These three concepts are then further developed by the remaining five people of the group. Hence the name 6-3-5 (Johannesson, et al., 2013). In this case the method could be called 4-3-3. This since there are four people who creates three concepts and then further develop the other three participant’s concepts. The session begun with an introduction of the problem and a general discussion on the topic. The group then got a paper with 12 squares on and a pen, see table 3. The first round the participants were given approximately 10 minutes to create the three first concepts. The remaining rounds were clocked and limited to five minutes. Table 3, principle layout of the paper used during the 3-4-4 method. The paper is divided into squares that the people in the idea generation session the fill out. Each person has a paper that everyone in the team get to sketch on. The shaded cells are just for explanation and not on the paper during a session.
Idea 1 Idea 2 Idea 3
Person 1 Person one: first
sketch Person one: second sketch Person one: third sketch
22 objectively look through the concepts as well as to look for strengths and weaknesses. The information is also meant to be used as background for further evaluations.
2.6.4 Kesselring criterion weight matrix
To narrow the concepts down even further a Kesselring criterion weight matrix was used. The matrix rates, with weight, how well the concept reaches set criterions, see table 4. They are then compared relative to each other to find how well they perform. The total points (T) a concept collects are then compared to the best total of the concepts (T/Tmax) (Johannesson, et al., 2013). Each concept is giving a r = rank and a t = total. Each criterion is giving a weight from one to five, each concept is then given a rank for how well it meets the criterion from one to five. The weight times the rank is the total. Table 4. Kesselring criterion weight matrix. Used for comparing the concepts to each other to find the best one. Criterion Concept 1 2 n… Weight r t r t r t 1 2 T = Sum tn T / TmaxRank (highest T/Tmax is #1)
36 Table 5. Olsson matrix. The matrix is used for generating product specification criterions. This one has one row less than the original which contains selling and distribution of the product. Life cycle phase Aspect
Process Environment Human Economy Creation (development, construction etc.) 1.1 1.2 1.3 1.4 Production (manuf., assembly, quality check etc.) 2.1 2.2 2.3 2.4 Usage (installation, user, service etc.) 3.1 3.2 3.3 3.4 Elimination (recycling, disposal etc.) 4.1 4.2 4.3 4.4 Table 6. Draft of product specification for new steering wheel. It cotains everything the final product must and can have.
Cell Criteria Must
Desired Restriction Function
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3.6.2 Relative decision matrix
By comparing the concepts to the current steering wheel a relative rank was given relative the current solution, see table 8. The method is called Pug’s relative decision matrix and is the second step in the evaluation process according to Johannesson, et al., (2013). The criterions are key words and aspects brought up along the project. Table 8. Relative decision matrix. Eliminates concepts that does not perform as much as others. Criteria Concept Ref.(0) 1 2 9 10 12 c i ≈ 9/10 l I II III IV
Innovative ref + + + + + ++ 0 + + + + + + + + Gives driver more "front" space ref + + + + + ++ + + + + + + + + + Gives driver more leg room ref 0 - + + + + + + + + + Adds extra value/features? ref - - + + 0 + 0 ++ ++ ++ + Gives a clear AD cure? ref + + + + + + + + + + + Ergonomic: gripping possibilities for driver ref 0 0 0 - 0 - + - - - - Ergonomic: additional adjustment possibilities ref 0 0 + + 0 0 0 + + 0 0 Reliazibility ref + + + + + + ++ 0 0 + 0 "Next" generation impression ref 0 0 + + 0 + + + + + + Sum 3 2 8 7 5 8 7 9 9 9 7
Continue Yes/No No No No Yes No No Yes* No Yes* Yes Yes Yes No
47 + New thinking + Redefines the interior - Requires space from the dashboard - Big construction when folded - Not as much gripping area as today’s steering wheel
Kesselring criterion weight matrix
With the use of the Kesselring matrix (table 9) the concepts were given a normalized rank relative the ideal solution. A robustness test resulted in approximately the same end result. Concept l and III are the overall winners, even if weight or ratings changes. Worth noting is that concept 9 & cl are not very far behind – they are all somewhat even in performance. Criterions are from further discussion about key words. Table 9. Kesselring criterion weight matrix. The matrix compares the concepts and brings out the best concepts based on the criterions given - this in relation to the other concepts. Criterion ConceptIdeal 9 cI I II III
50 A model with low level of details were created to validate function and test range of motion. The axial adjustment range is illustrated as a box with green dashed lines. The 2D extreme driving positions, seen from above are shown in figure 25 and 26. The concept saves approximately 130 mm in the axial direction. See figure 27. Figure 25. The concept can reach the current steering wheel adjustment in terms of axial length. Figure 26. The concept can go further back from the
54 A group brainstorming session was held with one lead engineer, one concept engineer and the project leader. The following ideas as well as requirements and wishes were brought up. The steering wheel should be able to adjust at least as much as the steering wheel can today. Preferably even more, the adjustment area should preferably, according to the ergonomics team, be around 70*50 mm (l x h). Compared to todays 65*40 (l x h), see green box in figure 37. For active safety, the steering system should have a collapse length of 120 mm (also known as ride down). This to have energy absorbing capabilities in the event of a crash. Still it should be very rigid when driving. Preferably it should also have adjustable steering wheel angle, also known as neck tilt. See figure 38. Several options for controlling the position of the arms was discussed. In order to reduce parts shown to the car’s passengers, only ideas that can be hidden behind the interior panel was discussed. Ideas that came up ca be seen in table 10. Table 10. Ways to controlling the position of the steering wheel.
Actuator Screw and nut drive Belt drive of sliders Hydraulic system Solenoid locking of slider
position Electromagnetic locking of slider position
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3.8 Concept recommendation
Finally, the further developed concept I and III compared to each other with a Kesselring decision matrix, see table 11. This to come to a conclusion about what concept is the better. Table 11. The final evaluation of the concepts were done with a weighter criterion matrix. Criterion Concept Ideal I IIIweight rating total r t r t
II The level of autonomy is usually talked about in terms of SAE definitions (from their international standard J3016). This thesis will focus on a steering aid that suits the needs of a level 4 automated vehicle. Wired UK (Burgees, 2017) posted a report about automation and wrote the following about level 4 automated vehicles: “SAE describes this as having "driving mode-specific performance by an automated driving system of all aspects of the dynamic driving task, even if a human driver does not respond appropriately to a request to intervene". Put more simply, if something goes wrong, the car can handle it itself.”
Preliminary Problem Statement
The steering wheel is nowadays always within a certain operating range because of the mechanical connection to the wheels. When this requirement is of excess and the level of automation has risen among car manufactures the steering wheel may not be used as much as it is today. This is an area that is yet to be further discovered and explored. Volvo wants to see what opportunities this technology might bring as to how the steering wheel may evolve and would like to know the following. How may a steering device for a level 4 automated car be designed? The project is about finding a solution for a steering device that mounts on the steering column (for human driving) that does not intrude as much on the driver’s personal space when car is put in autopilot. Thus allowing the driver to carry out tasks that cannot be done while “manually” driving; reading a newspaper, working on a laptop or eating for example. This because of both safety reason as well as lack of room. To alight with Volvo’s vision the primary target group is business commuters. They are workers that usually drive their car back and forth to work alone. This problem statement will be confronted with the method presented in Produktutveckling (Johannesson, et al., 2013) which follows the steps in Figure 1. During the project users with experience from autonomous-driving will give feedback to get user input into the project. This way the project follow a hybrid strategy; inside-out and partly outside-in design approach. Figure 42. Problem statement approachFeasibility
study specificationTarget generationConcept
Concept evaluation and choice
Layout
IV Responsible for academic guidance throughout the project. Project leader: Victor Wetterlind Responsible for the delivered result.
Project model
The project will use the following project model, which also acts as the critical path.Project
Phase
Milestone
Gate
date
Due
Responsible
Start
Project plan
done feb 07- Wetterlind Victor
Project plan accepted Leo de Vin
Feasibility
study
Research feb 16- Wetterlind Victor
Target
specification feb 16- Wetterlind Victor
Target spec. approved
16-feb Svensson Johan
Concept
Concept
storming feb 28- Wetterlind Victor
User
feedback Wetterlind Victor
Concept evaluation 02-mar Victor Wetterlind Concept approval mar 02- M.S J.S / D.K / Layout construction wee k 10 Victor Wetterlind Catia v5 course wee k 11 Victor Wetterlind
Methods report done mar 19- Wetterlind Victor
Half-way presentation
21-mar
Victor Wetterlind
Approved presentation half-way Leo de Vin
Constructio
n
Design review V.W J.S, D.J & Detail construction 18-maj Victor Wetterlind
V
Finishing
Thesis report due maj 25- Wetterlind Victor Project exhibition 31-maj Victor Wetterlind Final
presentation maj 31- Wetterlind Victor
presentation OK Exhibition and Leo de Vin
Peer review 7-jun Wetterlind Victor
VI The following steps are the preliminary methods chosen to complete the project with desired result.
Risk evaluation
To build in robustness and increase the chances of success a risk evaluation is done. With the purpose to find weak points in the process and find solutions to risks before they occur – this way it is possible to work around the problems and in some cases avoid them totally.Risk analysis
Risk P C R Solution
Project grows to big 4 5 20 Set clear delimitations and set a focus area to concentrate on (SW or mechanics) To advanced CAD-models 4 5 20 Discus problem with Johan/Daniel as well as simplify model To large target
specification 4 4 16
Reduce criteria’s with collaboration and approval from Johan/Daniel
Hard to find user group 4 4 16 Start looking early, ask around for Volvo AD teams with experience. Tesla drivers? Report not ready in time 3 5 15 Book time to write every week. Start well before due and work continually
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