Our private tour guide collected us from the port with an enthusiasm. As we left the port, I spotted something interesting: Morocco’s traffic stop signs read in Arabic script, rather than using the English “STOP” typical in so many other places, which I thought was pretty cool.

Where Two Oceans Meet

Cap Spartel, located approximately 14 kilometres west of Tangier, juts out 326 metres above sea level, a promontory that marks not only the meeting point of the Mediterranean Sea and the Atlantic Ocean, but also the northwestern edge of the African continent. The lighthouse standing sentinel on this rocky point was constructed by Sultan Muhammad IV in 1864, making it one of Morocco’s oldest lighthouses.

Near the lighthouse, a simple sign warned us not to feed the wild boars. The warning carried more historical weight than might first appear. The Barbary wild boar subspecies (Sus scrofa algira) inhabits the forested regions of North Africa, from Morocco through Algeria and Tunisia. An ironic thing is that Islam is the largest religion in Morocco, and they don’t eat pork, so whenever a boar is caught, they may be exported for sale elsewhere.

First Time Riding A Camel

Next, our guide arranged a camel ride on the beach as part of the day’s itinerary. While none of us explicitly asked for it, the camel ride was included in the tour package. The experience proved physically uncomfortable in ways I hadn’t anticipated. The animals had no traditional saddles, leaving my legs to dangle awkwardly while the camel’s gait sent jolts through my body with each step. At one point, the camel began walking the wrong way, and the handler slapped it on the head to correct its behaviour. This moment made me think about how these camels might not be treated well, and how we should avoid supporting such tourist activities next time.

The ride lasted approximately twenty minutes, though it felt considerably longer. The animal moved in jerky, unpredictable motions that kept me gripping tightly to avoid slipping sideways. When the time came to dismount, the camel lowered its head first, extending its front legs flat against the sand before tucking in its rear legs – a movement that made me feel as though we might flip forward over the animal’s neck. The whole experience left me tired despite sitting and with mixed feelings about the ethics of animal treatment in these settings.​

A Cave Made of Legends

The Hercules Caves hold a peculiar place between geology, mythology, and human labour. According to Greek legend, Hercules himself rested within these caves during the eleventh of his twelve labours, and some stories claim that he split the rock to create the Strait of Gibraltar. The cave’s opening to the sea has been carved into the unmistakable silhouette of the African continent, a feature believed to have been shaped by the Phoenicians in ancient times.

Yet the full story of the caves involves human hands as much as it does myth. Berber people quarried stone from the cave walls to craft millstones, and evidence of Neolithic occupation has been discovered within.

Obligatory Arranged Shopping Trip

Our guide’s next destinations were shopping stops, presented with an assurance that we weren’t obligated to purchase anything. Yet the dynamic felt awkward nonetheless. First came a rug shop, where a sales representative explained that hand-made rugs represented an investment, increasing in value over time with use. The pitch was not aggressive, but persistent. We remained sceptical – not only did we lack knowledge to evaluate what makes a rug worthy of its asking price, but the traditional designs on display clashed entirely with our home’s existing décor. It’s also not financially responsible to make a decision on a four-digit purchase within 15 minutes. We left empty-handed. The next destination though, a spice shop, proved more appealing.

The air hung with the mingled aromas of cumin, cinnamon, turmeric, and dozens of other powders and seeds. The vendor offered argan oil, a product for which Morocco is renowned. Argan trees grow nowhere else on Earth, thriving only in the arid and semi-arid regions of southwestern Morocco. We did end up selecting a few spice mixes and bottles of Argan oil to take home.

The Medina and Its Contradictions

Our guide seemed to possess a social network spanning the entire city. As we navigated the historical medina – that dense quarter of narrow alleyways where markets had operated for centuries – people would recognize him, calling out greetings. He’d pause to chat with shopkeepers and acquaintances, his connections evident in every interaction. The medina itself, however, told a different story about time and commerce. Once the true market of Tangier, it remains a marketplace physically, with shops lining the maze of streets. Yet the merchandise had largely shifted: where artisans once crafted goods by hand, now seems less likely.

The architecture retained its character – whitewashed walls, narrow passages designed for foot traffic, the occasional glimpse of a private courtyard, but the economic reality had transformed entirely. Another observation is that, despite French being an official language of Morocco, I heard it seldomly spoken. People spoke to each other in Arabic, and then English to the tourists. I didn’t even need to speak French at all, despite being comfortable enough in it to navigate around.

Meal Expectations Unfulfilled

Our guide led us to a Moroccan restaurant that catered entirely to cruise ship passengers and tourists, which assured us of safety in food hygiene, but a sign that the food wouldn’t be very good. As we sat down, we scanned the dining room and observed an absolute absence of locals. The meal opened with bread and mezze – a selection of eggplant, peppers, and tomatoes prepared simply but flavourfully. The first course confounded us: a puff pastry topped with powdered sugar and cinnamon arrived before the main dishes. This, we learned, was pastilla, a Moroccan speciality. Pastilla represents the sweet-savory fusion at the heart of Moroccan cuisine. It contained some meat wrapped in dough, but curiously topped with powdered sugar and cinnamon, creating a flavour profile we associated with dessert.

The main course consisted of chicken skewers with couscous, alongside beef stew and chicken stew (likely from a tagine, the traditional conical cooking vessel that permeates Moroccan cuisine). However, the dishes lacked adequate seasoning. The meat was tender enough, but without sufficient salt to draw out the spices’ potential, the meal felt somewhat muted.

The mint tea that concluded the meal redeemed the experience somewhat – hot, refreshing, infused with fresh mint leaves that had clearly come from somewhere nearby.

Returning Across the Strait

The ferry crossing back to Tarifa marked a transition from Morocco to Spain, from the medina’s complexity to European order.

Once we’d settled into our accommodation in Tarifa, we ventured to the hotel’s restaurant for seafood paella – a dish brimming with the flavours that a proper stock can provide, the broth enriched by the essence of shrimp, mussels, and fish. After a day navigating tours, negotiations, and sensory overload, the simple pleasure of excellent seafood felt like a proper ending, though ironically not a Moroccan meal.

Our time in Tangier offered cool highlights – the lighthouse, the legendary caves, and the medina’s winding streets. But the day also presented contradictions that made it memorable in unexpected ways. The camel ride proved far more uncomfortable than expected. The shopping stops tested our patience and skepticism. The restaurant catered so entirely to tourists that locals seemed relegated to a different Tangier altogether. Yet we’d glimpsed not merely the postcard version of a destination, but some of the friction inherent in modern tourism – the tension between preservation and commerce, between authentic space and commercialized experience.

You can view the photo album here

1.0 Motors

The chosen motors are:

• Finger grasping – Cytron IG32E-264K at a cost of USD $57.03 from RobotShop
• Finger sliding – Cytron MO-SPG-30E-20K at a cost of USD $22.58 from RobotShop

Both motors meet the torque speed requirements for this project.

1.1 Finger Grasping Actuation

From the initial budget, the budget set for actuators was set at $325.  The torque requirement needed for gripping was also calculated and each finger would require 4 Nm at its output to lift a 4 kg object using only the fingertips.  The evaluation criteria states that the device grasp as fast as possible and that the client would have the highest satisfaction if the device cost was less than $700.

Looking on several websites that sold motors, the following DC motor was chosen: Cytron IG32E-264K at a cost of USD $57.03 from RobotShop.  The specifications are as follows:

At 12 V with gearing included, the stall torque would be 20.7 Nm (without consideration of mechanical efficiency).  A motor with a high stall torque is also beneficial because it lowers the gear ratio required, which leads to the use of less space for gearing.  The motor also comes with its gearing, which contributes to its high torque.  Given the high stall torque of this motor addition gear reduction is not required.  During grasping, the motor will be exerting high torque at low speeds and therefore, the motor will be operating near the stall torque.  The torque here is more than sufficient even with mechanical efficiency losses accounted for.

For finger actuation before grasping occurs, there is a low load and therefore the motor will be operating closer to the no load speed.  The no load speed with gear reduction is 27.7 rpm (without consideration of mechanical efficiency).  Split among three output shafts, the speed would be 9.21 rpm.  Even with the load of the fingers accounted for, this is still acceptable. based on requirements and evaluation criteria.

While the torque is a lot higher than required, this motor was only more expensive than a motor of one size smaller by less than three dollars.  The electrical characteristics were also identical.  With a higher motor torque, the grasper would be comfortable in lifting objects even heavier than 4 kg, which is another benefit based on the evaluation criteria.

1.2 Finger Sliding Actuation

The motor required here does not require a large torque since motion in this degree of freedom is not expected to handle heavy loads.  This motor only requires enough torque to overcome the friction of the finger on the power screw that it is mounted on.  Therefore, a low-cost motor (relative to the grasping motor) will suffice.  The DC motor of choice is the Cytron MO-SPG-30E-20K at a cost of USD $22.58 from RobotShop.

The specifications are as follows:

The consistency of the stated specifications do not match the previous motor because the information that was provided by the manufacturer was not consistent.

An initial estimate of two 200 g fingers sliding on a 1/2” diameter power screw with a steel-steel sliding interface (friction coefficient of 0.8) shows that only 20 mNm of torque is required.  Therefore, this motor meets the requirement.  The power screw also has 13 threads per inch, and at the rated 185 rpm, the power screw would slide linearly at 6 mm/s.

1.3 Motor Type

DC and servo motors are motors that are suitable for the project.  An investigation between DC and servo motors showed that many manufacturers of motors did not provide the necessary specifications for choosing a servo motor in terms of the values of the no load, stall torque, and stall current.  While servos generate a lot of torque relative to their size when compared to DC motors, it is not feasible to use a servo motor because of the unknowns in the specifications.  It is possible to buy several servos and test them, but this is costly and time consuming.  At this stage in the project, the team is not able to commit the time to investigate further.

Comparison of the cost of the grasping motor relative to motors from Maxon Motor, a supplier of motors for UBC Thunderbots, shows that the price of a motor of the same power output costs approximately the same amount.  However, a fundamental difference is that the motor from Maxon does not include a gearbox, while the chosen motor for this project does.

2.0 Microcontroller

The microcontroller of choice is the Arduino Diecimila.  The primary motivator for using this board is because the UBC Thunderbots team already has this board and is currently unused.  The Thunderbots team has generously provided the board for use on this project.

The MCU will allow the turning the motors on and off, changing motor direction, changing motor speed, and reading encoder feedback.

3.0 Voltage Regulation for Encoders

Since the power supply is likely going to be run at 12 V, the encoders will require voltage regulation down to 5 V (the operating voltage of the encoder for the motors).  The chosen voltage regulator is the MC78L05A at a cost of USD from Digikey.  According to the typical application diagram of the datasheet, two capacitors will also be required (0.33 μF and 0.1 μF).  The cost of these are less than $1.

The voltage regulator will be wired up in this way as the datasheet shows:

The input will be from the 12 V source, and the output will be to the encoders.

4.0 Motor Driver

To control the motors, an H-Bridge is to be used.  However, due to the different current flows for each motor, one motor driver will require a high current capacity while the other one will not.  The high current capacity motor driver consists of a driving circuit using two half-bridges.  The low current capacity motor driver is made up of 1 IC.

4.1 Finger Grasping Motor Driver

To design the H-Bridge for controlling the motor, an L6205 motor driver will be used.  Each of them costs USD $11.36 from Digikey and can withstand a continuous current of 2.8 A and a peak current of 5.8 A and can be interfaced with the microcontroller with PWM inputs.  The driver can also be run in a parallel mode to double the current ratings by using both of its full bridges together.  The datasheet provides an application circuit as follows:

Output pins from the Arduino can turn the motor on and off through the enable pins.  Direction is controlled by adjusting the voltage polarity between IN1 and IN2.

There are also two output pins for current sensing.  By using it to measure the current draw, the microcontroller program can determine what the torque is through the use of the motor curves provided in the motor specifications.

4.2 Finger Sliding Motor Driver

The motor driver of choice is the L293D and each one costs $2.50 from Digikey.  Bidirectional control of a DC motor can be achieved by adapting the application circuit from the datasheet:

The 1A and 2A pins determine the direction of the motor or the motor deceleration.  A truth table is provided in the datasheet.

5.0 Power Supply

To power the grasper, a power supply plugged into the wall will be used.  It is expected that the future robot will have a power source of its own which will power the hand as well.  Therefore, for the purposes of testing the grasper for this project only a wall power supply will be required.

Looking at the maximum electrical power consumption of the two motors, the total comes to ~65 W (12 V * 5 A + 12 V * 0.41 A).  The other components also consume power and so the final power consumption will be higher.  To compensate, a 12 V power supply with a maximum wattage and current of 84 W and 7 A was selected.  The part number is CENB1090 and each costs USD $70.48 from Digikey.

6.0 Power Supply Connector

The power supply chosen has one port that uses a Molex Mini-Fit Jr. Receptacle.  Therefore, a proper receptacle must be used so that proper wire routing can power all the circuitry.  This also means that the future robot will also require a matching plug for this receptacle.

7.0 Fuses

Fuses will also be used as a redundant mechanism to stop the motor in case the current draw is too high.  The primary method of stopping the motor is through the current sense pins on the motor driver.

http://www.roymech.co.uk/Useful_Tables/Tribology/co_of_frict.htm