Retake Embedded Motion Control 2018 Nr3

This wiki describes and explains the software that was made for and implemented on the PICO robot to complete the retake of Embedded Motion Control course 2017-2018. The mission of the retake EMC 2018 is describe in the subsection ‘The challenge ‘Follow me!’’.

The robot that is used during the project is PICO. PICO has a holonomic wheelbase with which it can drive, a Laser Range Finder (LRF) from which it can gather information about the environment (blocked/free space) and wheels that are equipped with encoders to provide odometry data. All software that is developed has to be tested on the robot. There is also a simulator available which provides an exact copy of PICO’s functionalities. PICO itself has an on-board computer running Ubuntu 16.04. The programming language that is used during the course and the retake is C++ and Gitlab is used to store the code.

Student

TU/e Number	Name	E-mail
1037038	Daniël (D.J.M.) Bos	D.J.M.Bos@student.tue.nl

The challenge ‘Follow me!’

The main goal is to follow Person Of Interest (POI) in a cluttered environment. The person closest to PICO is the POI at standstill. The POI will walk a pre-defined route that’s unknown to the PICO. There are targets strip which the POI will cross in the middle. To prove whether PICO is able to follow the POI correctly, PICO should also cross these target strips. A overview of the setup is shown on Figure 1.

The are also other actors present in the area of interest. These actors will similarly as the POI start at standstill. After PICO has found his POI, i.e., the person closest to him, and has started his following-algorithm, all other actors will also walk around. The only restriction that the actors have is that they can never occlude the POI, i.e., they can not walk in between PICO and the POI. Figure 2 depicts a situation which can not occur.

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  Figure 2: A situation which can not occur for Level 1. In red we see PICO, blue the POI, and in darkgreen the actor.
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  Figure 2: A situation which can not occur for Level 1. In red we see PICO, blue the POI, and in darkgreen the actor.

Initial Design

Introduction:

For the initial design, the requirements will be discussed as well as the functions and their specifications. Moreover, a list of the used hardware components and the diagram of the interface are shown below.

Requirements

• Execute all tasks autonomously.
• The POI will start initially close to and is detectable at standstill.
• Finish the challenges within 2 minutes.
• The POI will move in such manner that, in most cases, two legs are visible.
• The POI will pass trough the middle of the target strips.
• The PICO must cross 80% of the target strips.
• The PICO must follow the POI at a distance of approximately 0.4 [m].
• Perform all tasks without bumping with a person.
• Perform all tasks without getting stuck in a loop.

Specifications The specifications are based on the requirements.

The POI

• The maximum velocity of the POI is 0.5 [m/s].
• The target strips are markers on the floor but PICO can’t recognize.
• The target strips are each 1 [m].

The PICO

• The maximal transitional velocity of PICO in any direction is 0.5 [m/s].
• The maximal rotational velocity of PICO is limited to 1.2 [rad/s]
• PICO should not stand still or make no sensible movements for periods over 30 [seconds].
• The PICO must follow the POI at maximum distance of 0.4±0.2 [m].
• PICO has to finish the challenge within 2 [min].

The targets strips

• The width of targets strips are each 1 [m].
• The number of target strips is around 5.

Skill function:

Task funciton: Components

To be able to execute the Follow me!’ challenges the PICO robot, already mentioned above, will be used. The following hardware components will be utilized: Actuators: Holonomic base with three omni-wheels.

Sensors:

• Laser range finder (LRF): To detect the distances to objects in the environment.
• Range: To be determined
• Field of view: 270 degrees
• Accuracy: To be determined

Computer running Ubuntu 16.04.

2Initial Design

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