This morning we met with two of our external designers, Jon and Robin, to discuss the progress of our project. We also met with the technician, Simon, who will be building the frame for our prototype. One question of particular concern is how RoboPlant’s ‘leaves’ are going to be connected to the stem. We came up with a number of different options, and these are summarised below.
The Ball Joint
The ball joint would have to be mechanically rotated by hand and would have ratchets at different levels so that the leaf could face different orientations and be locked in at a given position. A 90 degree rotation should suffice.
We are working out the optimal angles that the panels need to face, in order to work at their maximum capacity.
The pulley system
The pulley system would involve a central pulley being rotated round with the help of a spindle at the bottom of the plant. The connections could preferably be made via a tooth chain which would be connected to each leaf in the system. The leaves could start off at different orientations and then be rotated by a set angle so that all the leaves move by the same common angle.
Two systems have been thought of here:
- The use of a collimator to detect the sun which would then send a signal to the control system. The control system would then generate the appropriate signal and send in via the amplifier to the motor gearbox. A stepper motor could be used, however a gearbox needs to be connected to this in order to generate the appropriate torque needed. In this case a DC motor is used. The DC motor is connected to the leaf via a coupling/shock absorbed in order to stabilise the leaf. Implementing a control system is the only worry here, which seems to be beyond our current skill levels at the moment.
- The other system on the right involves the use of a high powered servo or stepper motor which is connected via a tooth chain. It acts as a pulley system which is connected to a rotatable spindle connected through the stem of the leaf. The tooth chain would be connected to either the spindle or the leaf directed which would make it rotate. This may need a control system.
The automated system could have a few leaves moving rather than having all if too complex, the rest of the leaves could be manually rotated via ball joints. Again we will are currently looking into this.
This was what the technicians suggested they were going to use for the prototype which involved a bar being rotated so that two of the leaves would rotate together. They could be initially oriented at different levels and move at the same angle with notches at set intervals that lock into place.
Note: The above are only theoretical ideas that we have come up with and have not been tested at any point in time by us.