Motion Planning Using an Impact-Based Hybrid Control for Trajectory Generation in Adaptive Walking

Abstract

This paper aims to solve a major drawback of walking robots i.e. their inability to react to environmental disturbances while navigating in natural rough terrains. This problem is reduced here by suggesting the use of a hybrid force-position control based trajectory generation with the impact dynamics into consideration that compensates for the stability variations, thus helping the robot react stably in the face of environmental disturbances. As a consequence, the proposed impact-based hybrid control helps the robot achieve better and stable motion planning than conventional position-based control algorithms. Dynamic simulations and real world outdoor experiments performed on a six legged hexapod robot show a relevant improvement in the robot locomotion.

Improving the Navigability of a Hexapod Robot Using a Fault-Tolerant Adaptive Gait

“…A physical model of our hexapod robot, which has previously been reported in earlier works [14][15][16][17][18][19], is shown in Fig. 1.…”

“…To solve this, we use a hybrid control framework that is a force-position-based controller for the attitude control as described in our earlier work [18] that switches the independent joint control from position to force as soon as the leg enters its landing phase in order to place the leg softly over the ground in an attempt to minimize drift and impulsive forces, using force feedback from the force sensing resistors. The method used in force control is to make the leg follow a desired trajectory using torque input to leg joints and stop the landing phase as soon as a force greater than the minimum threshold force of the force sensing resistor is detected by the controller, thereby ensuring that the leg is successfully placed over the ground.…”

“…Our control system uses the hybrid force-position-based controller [18] (as illustrated in Fig. 4) for attitude control with ZMPbased trajectory generation, and an integrated neuralnetwork-based FDD system.…”

“…In [17], we proposed a motion planning method based on landmark navigation using sensor tracking to influence the walking gait and perform straight-line walking with minimal path following errors. In [18], we mainly focused on motion-planning based on the impact dynamics involved in adaptive walking. To accomplish that feat, we proposed a control framework constituting a modified (with the impact dynamics into consideration) hybrid force-position controller to deal with the environmental disturbances.…”

3-D Biped Robot Walking along Slope with Dual Length Linear Inverted Pendulum Method (DLLIPM)

“…Furthermore, there are different groups of legged robots such as hexapod [3], quadruped [4] and biped [5][6][7][8][9][10][11][12][13][14][15][16][17]. The less the number of legs, the more difficult it is to ensure the dynamic balance of the robots.…”