Deciding on the design of the Nardinator:

The Nardinator was just one of five potential designs, as true engineers we picked the best design through the use of a morphologic overview. As can be seen from the chart, Design 4 became the basis for the Nardinator. Although this design won with only a slight difference, we all agreed that this design was significantly better than for example Design 5.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

       

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

We decided that is was important to have a design that allowed us to easily calculate the movement and strength of the final mechanism. It was also important to us that the gripping mechanism had a refined movement as to make sure it does not crush the objects it is supposed to pick up. However the chosen mechanism does need to have the force to hold on to a cup when it is transported upwards, so the strength of the gripping mechanism was also of significant importance. Of course the structure portrayed by the design has to be stable, especially when the pneumatics are suddenly activated. The design also needed to have the potential to lift a cup upwards 25 centimeters without too much difficulty, we formulated this under ‘Reach’. Last but not least we desired the design to be reasonably easy to produce and assemble, we called this criterion ‘Assembly’.

Not only did Design 4 get the highest overall score, the design scored reasonably well in all criteria. We only had a small issue with the finesse of the hand mechanism, however it did not render the complete design faulty.

 

Calculations on our design:

The maximum height that the system can lift:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Testing:

In the end, because we broke 2 of the links of our gripper arm during the day of testing, we were not able to do a full test with the gripper and we could not get the whole gripper working.

 

 

 

 

 

 

 

 

We did run into several issues with our design during the assembly. Firstly, we discovered that the M8 bolts and nuts that we used were too heavy and large. The weight of the bolts made it hard for our design to move its own weight, but construction of an iterated design that allowed us to use smaller bolts was denied, so we ended up with a heavy and clunky design.

M4 bolts would suffice in terms of strength and could severely reduce the weight of a future construction. Due to its own weight our lifting mechanism also displayed a lot of slack.  

Secondly, another issue occured when we tried to test our design. We wanted to test how much weight our gripper could handle, but when we started the actuator, one of our group members was still holding one of the links, so when the actuator was activated the link broke. Later that week a similar problem occured, because another link broke during transport. We then went on using eight links instead of ten.

After we assembled the gripping and lifting mechanisms we still needed to attach them and attach the gripper to the supplied board. We were no longer given the opportunity to have these pieces of the mechanism made out of perspex so wood became our only option. Eventually we constructed two beams through which the Nuremberg scissors could slide and the gripper mechanism could be attached, but we discovered that a lot of friction was created between the scissors and the wooden beams. We tried to smoothen the wood, but it did not change the result significantly. Last but not least we had trouble mounting the pneumatic actuators on our gripper. At the time we did not know the exact layout of the wooden supports in relation to the mechanism so we had not considered a definitive way to fasten the actuators. Luckily duct tape proved a very good fastener, with which you can fasten almost anything. 

The Nardinator features a relatively simple design consisting of a mechanical hand suspended from Nuremberg scissors.

All moving components were laser cut from Perspex to avoid big error margins in the components, which is a risk when components are handmade. We also used wood to support our scissor design from our lift mechanism to the mechanical hand. Everything is held together with stainless steel bolts and nuts, mostly M8 and some size M6, which, in hindsight had a high degree of redundancy for our design.

 

 

Getting hold of the cup

The bottom part of The Nardinator roughly resembles a lower arm in horizontal position.

The arm will move down, with the hand mechanism already around the cup that it is supposed

to pick up. The hand can then be closed as to grip the cup and keep it within the hand.

 

The hand like mechanism consists of two stationary fingers and two fingers which are operated

together with the same actuator. When closed the four fingers will form two ellipses above

eachother rather than two circles to compensate for misplacement of the cup.

 

 

 

The Nuremberg scissors

The centerpiece of the design is the scissor mechanism from which our gripping mechanism

is suspended. Usually Nuremberg scissors are used to push its load up or sideways, however in

this case it pulls its load upwards. The scissors are suspended from two joined wooden beams,

with a fixed pivot point at the front while the back part can slide and rotate through a slot in

the beams. The bottom side of the mechanism features a singular beam.

At the bottom, the front is also in a fixed position, only allowed to pivot while the back can slide

through a slot as well. The front is fixed to make sure that top and bottom will

remain vertically aligned.

Welcome to our website....

 

Hi! We are group 21, consisting of Joonas Hopman, Sophie Bekker, Ferran van der Klip, Stefan van Zijp and Liselotte Kraamwinkel. We have designed a mechanical gripper for our first group project in Mechanical Engineering at TU Delft. Come and discover our gripper on this page!

Lifting a cup 

 

The gripper should be able to lift a normal sized coffee cup made of plastic or cardboard.

Height of 25 cm

 

The reach of the arm of the gripper must be 25 cm in height. 

Different contents

 

The content of the cup may vary.

    About    

    The Assignment   

Imagery

The Design

    The Design Process  

These are videos of the parts that the Nardinator consists of: the arm of the gripper and the gripper mechanism itself. Unfortunately two links of  broke, therefore we were not able to capture the system as one on camera.

WB 21

From big to small: Ferran van der Klip, Joonas Hopman, Stefan van Zijp. Sophie Bekker and Liselotte Kraamwinkel

Evaluation